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an important source of background in direct searches for low-mass dark matter particles are the energy deposits by small-angle scattering of environmental γ rays. we report detailed measurements of low-energy spectra from compton scattering of γ rays in the bulk silicon of a charge-coupled device (ccd). electron recoils produced by γ rays from 57co and 241am radioactive sources are measured between 60 ev and 4 kev. the observed spectra agree qualitatively with theoretical predictions, and characteristic spectral features associated with the atomic structure of the silicon target are accurately measured for the first time. a theoretically motivated parametrization of the data that describes the compton spectrum at low energies for any incident γ -ray flux is derived. the result is directly applicable to background estimations for low-mass dark matter direct-detection experiments based on silicon detectors, in particular for the damic experiment down to its current energy threshold. | measurement of low energy ionization signals from compton scattering in a charge-coupled device dark matter detector |
this paper is the first report of n-type gaas as a cryogenic scintillation radiation detector for the detection of electron recoils from interacting dark matter (dm) particles in the poorly explored mev/c2 mass range. seven gaas samples from two commercial suppliers and with different silicon and boron concentrations were studied for their low temperature optical and scintillation properties. all samples are n-type even at low temperatures and exhibit emission between silicon donors and boron acceptors that peaks at 1.33 ev (930 nm). the lowest excitation band peaks at 1.44 ev (860 nm), and the overlap between the emission and excitation bands is small. the x-ray excited luminosities range from 7 to 43 photons/kev. thermally stimulated luminescence measurements show that n-type gaas does not accumulate metastable radiative states that could cause afterglow. further development and use with cryogenic photodetectors promises a remarkable combination of large target size, ultra-low backgrounds, and a sensitivity to electron recoils of a few ev that would be produced by dm particles as light as a few mev/c2. | cryogenic scintillation properties of n-type gaas for the direct detection of mev/c2 dark matter |
if dark matter has a finite size that is larger than its compton wavelength, the corresponding self-interaction cross section decreases with the velocity. we investigate the implications of this puffy dark matter for addressing the small-scale problems of the λ cold dark matter model and show that the way the nonrelativistic cross section varies with the velocity is largely independent of the dark matter internal structure. even in the presence of a light particle mediating self-interactions, we find that the finite-size effect may dominate the velocity dependence. we present an explicit example in the context of a qcd-like theory and discuss possible ways to differentiate puffy dark matter from the usual light-mediator scenarios. particularly relevant for this are low-threshold direct-detection experiments and indirect signatures associated with the internal structure of dark matter. | finite-size dark matter and its effect on small-scale structure |
what if the dark matter-nucleon scattering cross section is too small to be detected by direct detection experiments? it is well known in the literature that some interactions lead to dark matter-nucleon scattering cross sections that can be velocity and momentum suppressed. we show that in the case of bosonic dark matter, neutron star spectroscopy offers a possible detection. firstly, we discuss the case of scalar dark matter with scalar, pseudoscalar, and vector mediators. later, we do this exercise for vector dark matter. we show that, depending on the nature of dark matter and the interaction involved, neutron stars can improve the sensitivity on the dark matter-nucleon scattering cross section by orders of magnitude, representing a major step forward in the dark matter siege. | detecting bosonic dark matter with neutron stars |
we construct models of dark matter with suppressed spin-independent scattering cross section utilizing the existing simplified model framework. even simple combinations of simplified models can exhibit interference effects that cause the tree level contribution to the scattering cross section to vanish, thus demonstrating that direct detection limits on simplified models are not robust when embedded in a more complicated and realistic framework. in general for fermionic wimp masses ≳ 10 gev direct detection limits on the spin-independent scattering cross section are much stronger than those coming from the lhc. however these model combinations, which we call less-simplified models, represent situations where lhc searches become more competitive than direct detection experiments even for moderate dark matter mass. we show that a complementary use of several searches at the lhc can strongly constrain the direct detection blind spots by setting limits on the coupling constants and mediators' mass. we derive the strongest limits for combinations of vector + scalar, vector + "squark", and "squark" + scalar mediator, and present the corresponding projections for the lhc 14 tev for a number of searches: mono-jet, jets + missing energy, and searches for heavy vector resonances. | less-simplified models of dark matter for direct detection and the lhc |
scenarios for multi-component scalar dark matter based on a single zn (n ≥ 4) symmetry are simple and well-motivated. in this paper we investigate, for the first time, the phenomenology of the z5 model for two-component dark matter. this model, which can be seen as an extension of the well-known singlet scalar model, features two complex scalar fields — the dark matter particles — that are standard model singlets but have different charges under a z5 symmetry. the interactions allowed by the z5 give rise to novel processes between the dark matter particles that affect their relic densities and their detection prospects, which we study in detail. the key parameters of the model are identified and its viable regions are characterized by means of random scans. we show that, unlike the singlet scalar model, dark matter masses below the tev are still compatible with present data. even though the dark matter density turns out to be dominated by the lighter component, we find that current and future direct detection experiments may be sensitive to signals from both dark matter particles. | the z5 model of two-component dark matter |
we propose to introduce general messenger-matter interactions in the deflected anomaly mediated supersymmetry (susy) breaking (amsb) scenario to explain the gμ-2 anomaly. scenarios with complete or incomplete grand unified theory (gut) multiplet messengers are discussed, respectively. the introduction of incomplete gut mulitiplets can be advantageous in various aspects. we found that the gμ-2 anomaly can be solved in both scenarios under current constraints including the gluino mass bounds, while the scenarios with incomplete gut representation messengers are more favored by the gμ-2 data. we also found that the gluino is upper bounded by about 2.5 tev (2.0 tev) in scenario a and 3.0 tev (2.7 tev) in scenario b if the generalized deflected amsb scenarios are used to fully account for the gμ-2 anomaly at 3 σ (2 σ ) level. such a gluino should be accessible in the future lhc searches. dark matter (dm) constraints, including dm relic density and direct detection bounds, favor scenario b with incomplete gut multiplets. much of the allowed parameter space for scenario b could be covered by the future dm direct detection experiments. | solving the muon g -2 anomaly in deflected anomaly mediated susy breaking with messenger-matter interactions |
new experiments with spheres-gas (news-g) is a dark matter direct detection experiment that will operate at snolab (canada). similar to other rare-event searches, the materials used in the detector construction are subject to stringent radiopurity requirements. the detector features a 140-cm diameter proportional counter comprising two hemispheres made from commercially sourced 99.99% pure copper. such copper is widely used in rare-event searches because it is readily available, there are no long-lived cu radioisotopes, and levels of non-cu radiocontaminants are generally low. however, measurements performed with a dedicated 210po alpha counting method using an xia detector confirmed a problematic concentration of 210pb in bulk of the copper. to shield the proportional counter's active volume, a low-background electroforming method was adapted to the hemispherical shape to grow a 500-μm thick layer of ultra-radiopure copper to the detector's inner surface. in this paper the process is described, which was prototyped at pacific northwest national laboratory (pnnl), usa, and then conducted at full scale in the laboratoire souterrain de modane in france. the radiopurity of the electroplated copper was assessed through inductively coupled plasma mass spectrometry (icp-ms). measurements of samples from the first (second) hemisphere give 68% confidence upper limits of < 0 . 58μbq/kg (< 0 . 24μbq/kg) and < 0 . 26μbq/kg (< 0 . 11μbq/kg) on the 232th and 238u contamination levels, respectively. these results are comparable to previously reported measurements of electroformed copper produced for other rare-event searches, which were also found to have low concentration of 210pb consistent with the background goals of the news-g experiment. | copper electroplating for background suppression in the news-g experiment |
precise experimental setups for detection of variation of fundamental constants, scalar dark matter, or gravitational waves, such as laser interferometers, optical cavities, and resonant-mass detectors, are directly linked to measuring changes in material size. here we present calculated and experiment-derived estimates for both α and μ dependence of lattice constants and bond lengths of selected solid-state materials and diatomic molecules that are needed for interpretation of such experiments. | material size dependence on fundamental constants |
the use of simplified models as a tool for interpreting dark matter collider searches has become increasingly prevalent, and while early run ii results are beginning to appear, we look to see what further information can be extracted from the run i dataset. we consider three `standard' simplified models that couple quarks to fermionic singlet dark matter: an s-channel vector mediator with vector or axial-vector couplings, and a t-channel scalar mediator. upper limits on the couplings are calculated and compared across three alternate channels, namely mono-jet, mono- z (leptonic) and mono- w/z (hadronic). the strongest limits are observed in the mono-jet channel, however the computational simplicity and absence of significant t-channel model width effects in the mono-boson channels make these a straightforward and competitive alternative. we also include a comparison with relic density and direct detection constraints. | collide and conquer: constraints on simplified dark matter models using mono- x collider searches |
we study minimal benchmark models of dark matter with an extra anomaly-free u(1)' gauge boson z'. we find model parameters that give rise to the correct cosmological dark matter density while evading the latest direct detection searches for dark matter scattering produced by the xenon1t experiment, including the effects of z-z' mixing. we also find regions of parameter space that evade the constraints from lhc measurements of dileptons and dijets, precision electroweak measurements, and lhc searches for monojet events with missing transverse energy. we study two benchmark z' models with y-sequential couplings to quarks and leptons, one with a vector-like coupling to the dark matter particle and one with an axial dark matter coupling. the vector-like model is extremely tightly constrained, with only a narrow allowed strip where $m_\chi \simeq m_{z'}/2$, and the axial model is excluded within the parameter range studied. we also consider two leptophobic z$^\prime$ benchmark models, finding again narrow allowed strips where $m_\chi \simeq m_{z'}/2$ as well as more extended regions where $\log_{10} (m_\chi/ {\rm gev}) \gtrsim 3.2$. | phenomenological constraints on anomaly-free dark matter models |
we propose a novel dark matter detection method utilizing the excitation of superconducting transmon qubits. assuming the hidden photon dark matter of a mass of o (10 ) μ ev , the classical wave-matter oscillation induces an effective ac electric field via the small kinetic mixing with the ordinary photon. this serves as a coherent drive field for a qubit when it is resonant, evolving it from the ground state towards the first-excited state. we evaluate the rate of such evolution and observable excitations in the measurements, as well as the search sensitivity to the hidden photon dark matter. for a selected mass, one can reach ε ∼10-13- 10-12 (where ε is the kinetic mixing parameter of the hidden photon) with a few tens of seconds using a single standard transmon qubit. a simple extension to the frequency-tunable squid-based transmon enables the mass scan to cover the range of 4 - 40 μ ev (1-10 ghz) within a reasonable length of run time. the scheme has great potential to extend the sensitivity towards various directions including being incorporated into the cavity-based haloscope experiments or the currently available multibit noisy intermediate-scale quantum (nisq) computer machines. | detecting hidden photon dark matter using the direct excitation of transmon qubits |
we explore the reach of low-background experiments made of small quantities of heavy nuclear isotopes in probing the parameter space of inelastic dark matter that is kinematically inaccessible to classic direct detection experiments. through inelastic scattering with target nuclei, dark matter can yield a signal via either nuclear recoil or nuclear excitation. we present new results based on this approach, using data from low-energy gamma quanta searches in low-background experiments with hf and os metal samples and measurements with cawo4 and pbwo4 crystals as scintillating bolometers. we place novel bounds on wimpy inelastic dark matter up to mass splittings of about 640 kev and provide forecasts for the reach of future experiments. | pushing the frontier of wimpy inelastic dark matter: journey to the end of the periodic table |
we present a detection scheme to search for qcd axion dark matter, that is based on a direct interaction between axions and electrons explicitly predicted by dfsz axion models. the local axion dark matter field shall drive transitions between zeeman-split atomic levels separated by the axion rest mass energy mac2. axion-related excitations are then detected with an upconversion scheme involving a pump laser that converts the absorbed axion energy ( hundreds of μev) to visible or infrared photons, where single photon detection is an established technique. the proposed scheme involves rare-earth ions doped into solid-state crystalline materials, and the optical transitions take place between energy levels of 4fn electron configuration. beyond discussing theoretical aspects and requirements to achieve a cosmologically relevant sensitivity, especially in terms of spectroscopic material properties, we experimentally investigate backgrounds due to the pump laser at temperatures in the range 1.9 - 4.2 k. our results rule out excitation of the upper zeeman component of the ground state by laser-related heating effects, and are of some help in optimizing activated material parameters to suppress the multiphonon-assisted stokes fluorescence. | axion dark matter detection by laser induced fluorescence in rare-earth doped materials |
in scenarios where dark matter interacts differently with protons and neutrons (isospin-violating dark matter), the interpretation of the experimental limits on the dark matter spin-independent cross section may be significantly modified. on the one hand, the direct detection constraints are shifted depending on the target nucleus, possibly changing the hierarchy among different experiments. on the other hand, the relative strength between the bounds from neutrino detectors and those from direct detection experiments is altered, allowing the former to be more competitive. in this paper, the status of isospin-violating dark matter is assessed in the light of recent data, and the prospects for its detection in the near future are analyzed. we find, for example, that there are regions in the parameter space where icecube currently provides the most stringent limits on the spin-independent cross section, or others where the expected sensitivity of deap-3600 is well above the lux exclusion limit. our results highlight the complementarity among different targets in direct detection experiments, and between direct detection and neutrino searches in the quest for a dark matter signal. | isospin-violating dark matter in the light of recent data |
it was recently pointed out that direct detection signals from at least three different targets may be used to determine whether the dark matter (dm) particle is different from its antiparticle. in this work, we examine in detail the feasibility of this test under different conditions, motivated by proposals for future detectors. specifically, we perform likelihood fits to mock data under the hypotheses that the dm particle is identical to or different from its antiparticle, and determine the significance with which the former can be rejected in favor of the latter. in our analysis, we consider 3 different values of the dm mass (50 gev, 300 gev, 1 tev) and 4 different experimental ensembles, each consisting of at least 3 different targets — xe and ar plus one among the following: si, ge, cawo4, or ge/cawo4. for each of these experimental ensembles and each dm mass, the expected discrimination significance is calculated as a function of the dm-nucleon couplings. in the best case scenario, the discrimination significance can exceed o(3σ ) for three of the four ensembles considered, reaching o(5σ ) at special values of the dm-nucleon couplings. for the ensemble including si, o(5σ ) significance can be achieved for a range of dm masses and over a much wider range of dm-nucleon couplings, highlighting the need for a variety of experimental targets in order to determine the dm properties. these results show that future direct detection signals could be used to exclude, at a statistically significant level, a majorana or a real dm particle, giving a critical clue about the identity of the dark matter. | prospects for determining the particle/antiparticle nature of wimp dark matter with direct detection experiments |
dark matter (dm) simplified models are by now commonly used by the atlas and cms collaborations to interpret searches for missing transverse energy (etmiss). the coherent use of these models sharpened the lhc dm search program, especially in the presentation of its results and their comparison to dm direct-detection (dd) and indirect-detection (id) experiments. however, the community has been aware of the limitations of the dm simplified models, in particular the lack of theoretical consistency of some of them and their restricted phenomenology leading to the relevance of only a small subset of etmiss signatures. this document from the lhc dark matter working group identifies an example of a next-generation dm model, called 2hdm +a , that provides the simplest theoretically consistent extension of the dm pseudoscalar simplified model. a comprehensive study of the phenomenology of the 2hdm +a model is presented, including a discussion of the rich and intricate pattern of mono- x signatures and the relevance of other dm as well as non-dm experiments. based on our discussions, a set of recommended scans are proposed to explore the parameter space of the 2hdm +a model through lhc searches. the exclusion limits obtained from the proposed scans can be consistently compared to the constraints on the 2hdm +a model that derive from dd, id and the dm relic density. | lhc dark matter working group: next-generation spin-0 dark matter models |
this document summarises the proposal of the lhc dark matter working group on how to present lhc results on s-channel simplified dark matter models and to compare them to direct (indirect) detection experiments. | recommendations on presenting lhc searches for missing transverse energy signals using simplified s-channel models of dark matter |
we examine the consequences of the effective field theory (eft) of dark matter-nucleon scattering for current and proposed direct detection experiments. exclusion limits on eft coupling constants computed using the optimum interval method are presented for supercdms soudan, cdms ii, and lux, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. we demonstrate that spectral differences between the standard dark matter model and a general eft interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. we also discuss the implications of the eft for the next-generation (g2) direct detection experiments and point out regions of complementarity in the eft parameter space. | dark matter effective field theory scattering in direct detection experiments |
we study the case of multi-component dark matter, in particular how direct detection signals are modified in the presence of several stable weakly-interacting-massive particles. assuming a positive signal in a future direct detection experiment, stemming from two dark matter components, we study the region in parameter space where it is possible to distinguish a one from a two-component dark matter spectrum. first, we leave as free parameters the two dark matter masses and show that the two hypotheses can be significantly discriminated for a range of dark matter masses with their splitting being the critical factor. we then investigate how including the effects of different interaction strengths, local densities or velocity dispersions for the two components modifies these conclusions. we also consider the case of isospin-violating couplings. in all scenarios, we show results for various types of nuclei both for elastic spin-independent and spin-dependent interactions. finally, assuming that the two-component hypothesis is confirmed, we quantify the accuracy with which the parameters can be extracted and discuss the different degeneracies that occur. this includes studying the case in which only a single experiment observes a signal, and also the scenario of having two signals from two different experiments, in which case the ratios of the couplings to neutrons and protons may also be extracted. | on the direct detection of multi-component dark matter: sensitivity studies and parameter estimation |
what if the dark matter-nucleon scattering cross section is too small to be detected by direct detection experiments? it is well known in the literature that some interactions lead to dark matter-nucleon scattering cross sections that can be velocity and momentum suppressed. we show that in the case of bosonic dark matter, neutron star spectroscopy offers a possible detection. firstly, we discuss the case of scalar dark matter with scalar, pseudoscalar, and vector mediators. later, we do this exercise for vector dark matter. we show that, depending on the nature of dark matter and the interaction involved, neutron stars can improve the sensitivity on the dark matter-nucleon scattering cross section by orders of magnitude, representing a major step forward in the dark matter siege. | detecting bosonic dark matter with neutron stars |
we scrutinise the widely studied minimal scotogenic model of dark matter (dm) and radiative neutrino mass from the requirement of a strong first order electroweak phase transition (ewpt) and observable gravitational waves at future planned space based experiments. the scalar dm scenario is similar to inert scalar doublet extension of standard model where a strong first order ewpt favours a portion of the low mass regime of dm which is disfavoured by the latest direct detection bounds. in the fermion dm scenario, we get newer region of parameter space which favours strong first order ewpt as the restriction on mass ordering within inert scalar doublet gets relaxed. while such leptophilic fermion dm remains safe from stringent direct detection bounds, newly allowed low mass regime of charged scalar can leave tantalising signatures at colliders and can also induce charged lepton flavour violation within reach of future experiments. while we get such new region of parameter space satisfying dm relic, strong first order ewpt with detectable gravitational waves, light neutrino mass and other relevant constraints, we also improve upon previous analysis in similar model by incorporating appropriate resummation effects in effective finite temperature potential. | observable gravitational waves in minimal scotogenic model |
producing an acceptable thermal relic abundance of dark matter with masses ≫ 102 tev is a challenge. we propose a novel mechanism where gev-scale states establish a tiny thermal relic abundance for dark matter, which is later promoted to ultra massive status by a very light scalar. we refer to this dark matter as a thermal ultra massive particle (thump). direct detection of thumps can be naturally expected due to large scattering cross sections mediated by low mass states that couple thumps to the standard model. our model generically leads to signals for the associated gev-scale states at accelerator experiments. | getting a thump from a wimp |
identifying the true theory of dark matter depends crucially on accurately characterizing interactions of dark matter (dm) with other species. in the context of dm direct detection, we present a study of the prospects for correctly identifying the low-energy effective dm-nucleus scattering operators connected to uv-complete models of dm-quark interactions. we take a census of plausible uv-complete interaction models with different low-energy leading-order dm-nuclear responses. for each model (corresponding to different spin-, momentum-, and velocity-dependent responses), we create a large number of realizations of recoil-energy spectra, and use bayesian methods to investigate the probability that experiments will be able to select the correct scattering model within a broad set of competing scattering hypotheses. we conclude that agnostic analysis of a strong signal (such as generation-2 would see if cross sections are just below the current limits) seen on xenon and germanium experiments is likely to correctly identify momentum dependence of the dominant response, ruling out models with either "heavy" or "light" mediators, and enabling downselection of allowed models. however, a unique determination of the correct uv completion will critically depend on the availability of measurements from a wider variety of nuclear targets, including iodine or fluorine. we investigate how model-selection prospects depend on the energy window available for the analysis. in addition, we discuss accuracy of the dm particle mass determination under a wide variety of scattering models, and investigate impact of the specific types of particle-physics uncertainties on prospects for model selection. | identifying the theory of dark matter with direct detection |
the nature of dark matter is one of the greatest mysteries in modern physics and astronomy. a wide variety of experiments have been carried out worldwide to search for the evidence of particle dark matter. chinese physicists started experimental search for dark matter about ten years ago, and have produced results with high scientific impact. in this paper, we present an overview of the dark matter program in china, and discuss recent results and future directions. | experimental search for dark matter in china |
the general strategy for dark matter (dm) searches at colliders currently relies on simplified models. in this paper, we propose a new t-channel uv-complete simplified model that improves the existing simplified dm models in two important respects: (i) we impose the full sm gauge symmetry including the fact that the left-handed and the right-handed fermions have two independent mediators with two independent couplings, and (ii) we include the renormalization group evolution when we derive the effective lagrangian for dm-nucleon scattering from the underlying uv complete models by integrating out the t-channel mediators. the first improvement will introduce a few more new parameters compared with the existing simplified dm models. in this study we look at the effect this broader set of free parameters has on direct detection and the mono- x + met ( x=jet, w,z) signatures at 13tev lhc while maintaining gauge invariance of the simplified model under the full sm gauge group. we find that the direct detection constraints require dm masses less than 10 gev in order to produce phenomenologically interesting collider signatures. additionally, for a fixed mono-w cross section it is possible to see very large differences in the mono-jet cross section when the usual simplified model assumptions are loosened and isospin violation between rh and lh dm-sm quark couplings are allowed. | simplified dm models with the full sm gauge symmetry: the case of t-channel colored scalar mediators |
dark matter (dm), arising from an inert higgs doublet, may either be light, below the w mass, or heavy, above about 525 gev. while the light region may soon be excluded, the heavy region is known to be very difficult to probe with either direct detection (dd) experiments or the large hadron collider (lhc). we show that adding a second inert higgs doublet helps to make the heavy dm region accessible to both dd and the lhc, by either increasing its couplings to the observed higgs boson, or lowering its mass to 360 gev ≲ m dm, or both. | observable heavy higgs dark matter |
we introduce and experimentally implement a method for the detector calibration of photon-number-resolving time-bin multiplexing layouts based on the measured click statistics of superconducting nanowire detectors. in particular, the quantum efficiencies, the dark count rates, and the positive operator-valued measures of these measurement schemes are directly obtained with high accuracy. the method is based on the moments of the click-counting statistics for coherent states with different coherent amplitudes. the strength of our analysis is that we can directly conclude—on a quantitative basis—that the detection strategy under study is well described by a linear response function for the light-matter interaction and that it is sensitive to the polarization of the incident light field. moreover, our method is further extended to a two-mode detection scenario. finally, we present possible applications for such well-characterized detectors, such as sensing of atmospheric loss channels and phase sensitive measurements. | direct calibration of click-counting detectors |
we present new results on the radiopurity of a 3.4-kg nai(tl) crystal scintillator operated in the sabre proof-of-principle detector setup. the amount of potassium contamination, determined by the direct counting of radioactive 40k, is found to be 2.2 ±1.5 ppb , lowest ever achieved for nai(tl) crystals. with the active veto, the average background rate in the crystal in the 1-6 kev energy region of interest (roi) is 1.20 ±0.05 counts /day /kg /kev , which is a breakthrough since the dama/libra experiment. our background model indicates that the rate is dominated by 210pb and that about half of this contamination is located in the polytetrafluoroethylene reflector. we discuss ongoing developments of the crystal manufacture aimed at the further reduction of the background, including data from purification by zone refining. a projected background rate lower than ∼0.2 counts /day /kg /kev in the roi is within reach. these results represent a benchmark for the development of next-generation nai(tl) detector arrays for the direct detection of dark matter particles. | high sensitivity characterization of an ultrahigh purity nai(tl) crystal scintillator with the sabre proof-of-principle detector |
we discuss the most sensitive constraints on light dark matter (ldm) from accelerator experiments na64 and babar and compare it with recent results from direct searches at xenon1t, damic-m, supercdms, and darkside-50. we show that for the dark photon ($a'$) model with scalar ldm, na64 gives more stringent bounds for $a'$ masses $m_{a'} \leq 0.15~gev$ than direct searches. moreover, for the case of majorana ldm the damping dm velocity $v$ factor, $v^2 \sim o(10^{-6})$, for the elastic ldm electron(nucleon) cross section makes direct observation of majorana ldm extremely challenging, while the absence of this suppression in the na64 case gives an advantage to the experiment. the similar situation takes place for pseudo-dirac ldm. the babar provides the most stringent bounds for $a'$ masses $m_{a'} \geq 0.35~gev$. for scalar ldm the direct detection experiments give more stringent bounds at $m_{a'} \geq 0.35~gev$ while for majorana and pseudo-dirac ldm case, the babar bounds are more stringent. the complementarity of the two approaches in searching for ldm is underlined. | search for light dark matter with accelerator and direct detection experiments: comparison and complementarity of recent results |
the direct search for dark matter in the form of weakly interacting massive particles (wimp) is performed by detecting nuclear recoils (nr) produced in a target material from the wimp elastic scattering. a promising experimental strategy for direct dark matter search employs argon dual-phase time projection chambers (tpc). one of the advantages of the tpc is the capability to detect both the scintillation and charge signals produced by nrs. furthermore, the existence of a drift electric field in the tpc breaks the rotational symmetry: the angle between the drift field and the momentum of the recoiling nucleus can potentially affect the charge recombination probability in liquid argon and then the relative balance between the two signal channels. this fact could make the detector sensitive to the directionality of the wimp-induced signal, enabling unmistakable annual and daily modulation signatures for future searches aiming for discovery. the recoil directionality (red) experiment was designed to probe for such directional sensitivity. the tpc of red was irradiated with neutrons at the infn laboratori nazionali del sud, and data were taken with 72 kev nrs of known recoil directions. the direction-dependent liquid argon charge recombination model by cataudella et al. was adopted and a likelihood statistical analysis was performed, which gave no indications of significant dependence of the detector response to the recoil direction. the aspect ratio r of the initial ionization cloud is estimated to be 1.037 +/- 0.027 and the upper limit is r < 1.072 with 90% confidence level | directionality of nuclear recoils in a liquid argon time projection chamber |
squeezed states of light have been used extensively to increase the precision of measurements, from the detection of gravitational waves to the search for dark matter. in the optical domain, high levels of vacuum noise squeezing are possible due to the availability of low loss optical components and high-performance squeezers. at microwave frequencies, however, limitations of the squeezing devices and the high insertion loss of microwave components makes squeezing vacuum noise an exceptionally difficult task. here we demonstrate a new record for the direct measurement of microwave squeezing. we use an ultra low loss setup and weakly-nonlinear kinetic inductance parametric amplifiers to squeeze microwave noise 7.8(2) db below the vacuum level. the amplifiers exhibit a resilience to magnetic fields and permit the demonstration of record squeezing levels inside fields of up to 2 t. finally, we exploit the high critical temperature of our amplifiers to squeeze a warm thermal environment, achieving vacuum level noise at a temperature of 1.8 k. these results enable experiments that combine squeezing with magnetic fields and permit quantum-limited microwave measurements at elevated temperatures, significantly reducing the complexity and cost of the cryogenic systems required for such experiments. | strong microwave squeezing above 1 tesla and 1 kelvin |
cresst is one of the most prominent direct detection experiments for dark matter particles with sub-gev/c2 mass. one of the advantages of the cresst experiment is the possibility to include a large variety of nuclides in the target material used to probe dark matter interactions. in this work, we discuss in particular the interactions of dark matter particles with protons and neutrons of 6li. this is now possible thanks to new calculations on nuclear matrix elements of this specific isotope of li. to show the potential of using this particular nuclide for probing dark matter interactions, we used the data collected previously by a cresst prototype based on lialo2 and operated in an above ground test-facility at max-planck-institut für physik in munich, germany. in particular, the inclusion of 6li in the limit calculation drastically improves the result obtained for spin-dependent interactions with neutrons in the whole mass range. the improvement is significant, greater than two order of magnitude for dark matter masses below 1 gev/c2, compared to the limit previously published with the same data. | probing spin-dependent dark matter interactions with 6li |
the search for a dark matter particle is the new grail and hard-sought nirvana of the particle physics community. from the theoretical side, it is the main challenge to provide a consistent and model-independent tool for comparing the bounds and reach of the diverse experiments. we propose a first complete classification of minimal consistent dark matter models, abbreviated as mcdms, that are defined by one dark matter weak multiplet with up to one mediator multiplet. this classification provides the missing link between experiments and top-down models. consistency is achieved by imposing renormalisability and invariance under the full standard model symmetries. we apply this paradigm to the fermionic dark matter case. we also reconsider the one-loop contributions to direct detection, including the relevant effect of (small) mass splits in the dark multiplet. our work highlights the presence of unexplored viable models, and paves the way for the ultimate systematic hunt for the dark matter particle. | minimal consistent dark matter models for systematic experimental characterisation: fermion dark matter |
dark matter direct (and indirect) detection experiments usually can only determine a specific combination of a power of the coupling and the dark matter density. this is also true for axion haloscopes which are sensitive to the product $g^{2}_{a\gamma\gamma}\rho_{\rm dm}$, the combination of axion-photon coupling squared and the dark matter density. in this note we show, that in the lucky case when we intersect with a so-called axion minicluster of a suitable size, we can utilize the spectral information available in haloscopes to determine the gravitational potential of the minicluster. we can then use this to measure separately the coupling and the density of the minicluster. | using axion miniclusters to disentangle the axion-photon coupling and the dark matter density |
we consider a natural asymmetric dark matter (adm) model in the mirror twin higgs (mth). we show that it is possible to obtain the correct dark matter (dm) abundance when a twin baryon is the dm without the need of explicit breaking of the mth &z;2 symmetry in the dimensionless couplings (i.e. without hard &z;2 breaking). we illustrate how this is possible in a specific baryogenesis setup, which also leads to adm. in the simplest scenario we obtain mdm ~ o(1) gev, just above the proton mass. we show estimates for direct detection rates at present and future experiments. | baryogenesis and dark matter in the mirror twin higgs |
existing xenon dark matter (dm) direct detection experiments can probe the dm-nucleon interaction of dm with a sub-gev mass through a search for photon emission from the recoiling xenon atom. we show that lux's constraints on sub-gev dm, which utilize the scintillation (s1) and ionization (s2) signals, are approximately 3 orders of magnitude more stringent than previous xenon constraints in this mass range, derived from the xenon10 and xenon100 s2-only searches. the new lux constraints provide the most stringent direct detection constraints for dm particles with a mass below 0.5 gev. in addition, the photon emission signal in lux and its successor lz maintain the discrimination between background and signal events so that an unambiguous discovery of sub-gev dm is possible. we show that lz has the potential to reconstruct the dm mass with ≃20 % accuracy for particles lighter than 0.5 gev. | new constraints and discovery potential of sub-gev dark matter with xenon detectors |
investigated in this work were sensitivities of a prototype detector for the detection of low-mass dark matter particles produced at the spallation neutron source at the oak ridge national laboratory in 2 years of data taking. the presumed prototype consisted of 10 kg undoped csi or nai scintillation crystals directly coupled with sipm arrays operated at 77 k. compared to the coherent csi(na) detector, a much higher light yield was assumed for the prototype. an experiment with a cylindrical 1 kg undoped csi crystal coupled directly to two photomultiplier tubes at about 77 k was conducted as the first step to verify the idea. a light yield of 26.0 ±0.4 photoelectrons per kev electron-equivalent was achieved. this eliminated the concern of self light absorption in large crystals raised in some of the early studies. | prospect of undoped inorganic crystals at 77 kelvin for low-mass dark matter search at spallation neutron source |
atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. such an interaction involving leptophilic weakly interacting massive particles (wimps) is a promising possible explanation for the anomalous 9 σ annual modulation in the dama dark matter direct detection experiment [r. bernabei et al., eur. phys. j. c 73, 2648 (2013)]. we demonstrate the applicability of the born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving wimps. conventional wisdom has it that the ionization probability for such a process should be exponentially small. we show, however, that due to nonanalytic, cusplike behavior of coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. we also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times. | ionization of atoms by slow heavy particles, including dark matter |
we analyse the mass reach for electroweakinos at future hadron colliders and their interplay with direct detection experiments. motivated by the lhc data, we focus on split supersymmetry models with different electroweakino spectra. we find for example that a 100 tev collider may explore winos up to ∼ 7 tev in low scale gauge mediation models or thermal wino dark matter around 3 tev in models of anomaly mediation with long-lived winos. we show moreover how collider searches and direct detection experiments have the potential to cover large part of the parameter space even in scenarios where the lightest neutralino does not contribute to the whole dark matter relic density. | hunting electroweakinos at future hadron colliders and direct detection experiments |
we analyze the direct detection signals of a toy model consisting of a dirac dark matter particle which couples to one standard model fermion via a scalar mediator. for all scenarios, the dark matter particle scatters off nucleons via one loop-induced electromagnetic and electroweak moments, as well as via the one-loop exchange of a higgs boson. besides, and depending on the details of the model, the scattering can also be mediated at tree level via the exchange of the scalar mediator or at one loop via gluon-gluon interactions. we show that, for thermally produced dark matter particles, the current limits from the lux experiment on these scenarios are remarkably strong, even for dark matter coupling only to leptons. we also discuss future prospects for xenon1t and darwin and we argue that multi-ton xenon detectors will be able to probe practically the whole parameter space of the model consistent with thermal production and perturbativity. we also discuss briefly the implications of our results for the dark matter interpretation of the galactic gev excess. | dirac dark matter with a charged mediator: a comprehensive one-loop analysis of the direct detection phenomenology |
pandax-4t is a dark matter direct detection experiment located in china jinping underground laboratory. the central apparatus is a dual-phase xenon detector containing 4 ton liquid xenon in the sensitive volume, with about 500 photomultipliers instrumented in the top and the bottom of the detector. in this paper we present a completely new system of readout electronics and data acquisition in the pandax-4t experiment. compared to the one used in the previous pandax dark matter experiments, the new system features triggerless readout and higher bandwidth. with triggerless readout, dark matter searches are not affected by the efficiency loss of external triggers. the system records single photelectron signals of the dominant pmts with an average efficiency of 96%, and achieves the bandwidth of more than 450 mb/s. the system has been used to successfully acquire data during the commissioning runs of pandax-4t. | readout electronics and data acquisition system of pandax-4t experiment |
classical scale invariance is one of the possible solutions to explain the origin of the electroweak scale. the simplest extension is the classically scale-invariant standard model augmented by a multiplet of gauge singlet real scalar. in the previous study it was shown that the properties of the higgs potential deviate substantially, which can be observed in the international linear collider. on the other hand, since the multiplet does not acquire vacuum expectation value, the singlet components are stable and can be dark matter. in this letter we study the detectability of the real singlet scalar bosons in the experiment of the direct detection of dark matter. it is shown that a part of this model has already been excluded and the rest of the parameter space is within the reach of the future experiment. | direct detection of singlet dark matter in classically scale-invariant standard model |
assuming for weakly interacting massive particles (wimps) a maxwellian velocity distribution in the galaxy we explore in a systematic way the relative sensitivity of an extensive set of existing and projected dark matter (dm) direct detection experiments to each of the 14 couplings that parameterize the most general non-relativistic (nr) effective hamiltonian allowed by galilean invariance for a contact interaction driving the elastic scattering off nuclei of wimps of spin 1/2. we perform our analysis in terms of two free parameters: the wimp mass mχ and the ratio between the wimp-neutron and the wimp-proton couplings cn/cp. we include the modified signal spectral shape due to non-standard interactions when it is needed in the determination of the bound, such as in the case of background subtraction or of the application of the optimal-interval method. for each coupling, in the mχ-cn/cp plane we provide contour plots of the most stringent 90% c.l. bound on the wimp-nucleon cross section and show the experiment providing it. we also introduce nrdd_constraints, a simple interpolating code written in python that allows to obtain the numerical value of the bound as a function of the wimp mass mχ and of the coupling ratio cn/cp for each nr coupling. we find that 9 experiments out of the 14 present dark matter searches considered in our analysis provide the most stringent bound on some of the effective couplings for a given choice of (mχ, cn/cp): this is evidence of the complementarity of different target nuclei and/or different combinations of count-rates and energy thresholds when the search of dm is extended to a wide range of possible interactions. | present and projected sensitivities of dark matter direct detection experiments to effective wimp-nucleus couplings |
a radiative natural susy spectrum are proposed in the deflected anomaly mediation scenario with general messenger-matter interactions. due to the contributions from the new interactions, positive slepton masses as well as a large | at | term can naturally be obtained with either sign of deflection parameter and few messenger species (thus avoid the possible landau pole problem). in this scenario, in contrast to the ordinary (radiative) natural susy scenario with under-abundance of dark matter (dm), the dm can be the mixed bino-higgsino and have the right relic density. the 125 gev higgs mass can also be easily obtained in our scenario. the majority of low ew fine tuning points can be covered by the xenon-1t direct detection experiments. | radiative natural susy spectrum from deflected amsb scenario with messenger-matter interactions |
we discuss the possibility to detect spin 0, 1 and 1/2 dark matter (dm) at future e+e- colliders. the models considered here are simple, consistent and renormalizable field theories that provide correct dm abundance and satisfy direct detection, indirect detection and collider constraints. the intention of this paper was to verify to what extent it might be possible to disentangle models of different dm spins by the measurement of the cross section for e+e-→ z + ⋯ at future e+e- colliders. we specialize to the case of the ilc operating at √{s } = 250 gev, however our results apply as well for the fcc-ee and the cepc colliders. for each model the cross section maximized with respect to parameters was calculated and compared to the expected 95% cl cross-section limits estimated for the ilc. it turned out that near the 2mdm ≃ m1,2 resonances, where m1 and m2 are the sm higgs boson and a non-standard higgs boson masses, respectively, there exist substantial regions where the models are testable. a special attention has been payed to calculation of the cross section in the region where m1 ≃ m2. | dark-matter-spin effects at future e+e- colliders |
the search for sub-gev dark matter (dm) particles via electronic transitions in underground detectors attracted much theoretical and experimental interest in the past few years. a still open question in this field is whether experimental results can in general be interpreted in a framework where the response of detector materials to an external dm probe is described by a single ionisation or crystal form factor, as expected for the so-called dark photon model. here, ionisation and crystal form factors are examples of material response functions: interaction-specific integrals of the initial and final state electron wave functions. in this work, we address this question through a systematic classification of the material response functions induced by a wide range of models for spin-0, spin-1/2 and spin-1 dm. we find several examples for which an accurate description of the electronic transition rate at dm direct detection experiments requires material response functions that go beyond those expected for the dark photon model. this concretely illustrates the limitations of a framework that is entirely based on the standard ionisation and crystal form factors, and points towards the need for the general response-function-based formalism we pushed forward recently [1,2]. for the models that require non-standard atomic and crystal response functions, we use the response functions of [1,2] to calculate the dm-induced electronic transition rate in atomic and crystal detectors, and to present 90% confidence level exclusion limits on the strength of the dm-electron interaction from the null results reported by xenon10, xenon1t, edelweiss and sensei. | dark matter-electron interactions in materials beyond the dark photon model |
we further study the effect of neutral bremsstrahlung (nbrs) in two-phase argon electroluminescence (el), revealed recently in buzulutskov et al. (2018). the absolute el yield due to nbrs effect, in the visible and nir range, was remeasured in pure gaseous argon in the two-phase mode, using a two-phase detector with el gap read out directly by cryogenic pmts and sipms. possible applications of the nbrs effect in detection science are discussed, including those in two-phase dark matter detectors. | neutral bremsstrahlung in two-phase argon electroluminescence: further studies and possible applications |
we study the orbital phase space of dark matter (dm) haloes in the auriga suite of cosmological hydrodynamics simulations of milky way (mw) analogues. we characterize haloes by their spherical action distribution, $f\left(j_{{r}},l\right)$ , a function of the specific angular momentum, l, and the radial action, jr, of the dm particles. by comparing dm-only and hydrodynamical simulations of the same haloes, we investigate the contraction of dm haloes caused by the accumulation of baryons at the centre. we find a small systematic suppression of the radial action in the dm haloes of the hydrodynamical simulations, suggesting that the commonly used adiabatic contraction approximation can result in an underestimate of the density by $\sim 8{{ \rm {per\ cent}}}$ . we apply an iterative algorithm to contract the auriga dm haloes given a baryon density profile and halo mass, recovering the true contracted dm profiles with an accuracy of $\sim 15{{ \rm {per\ cent}}}$ , that reflects halo-to-halo variation. using this algorithm, we infer the total mass profile of the mw's contracted dm halo. we derive updated values for the key astrophysical inputs to dm direct detection experiments: the dm density and velocity distribution in the solar neighbourhood. | the orbital phase space of contracted dark matter haloes |
we report constraints on the dark photon effective kinetic mixing parameter (κ ) with data taken from two p -type point-contact germanium detectors of the cdex-10 experiment at the china jinping underground laboratory. the 90% confidence level upper limits on κ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses (mv) from 10 to 300 ev /c2 in direct detection experiments. considering dark photon as the cosmological dark matter, limits at 90% confidence level with mv from 0.1 to 4.0 kev /c2 are set from 449.6 kg-day data, with a minimum of κ =1.3 ×10-15 at mv=200 ev /c2 . | direct detection constraints on dark photons with the cdex-10 experiment at the china jinping underground laboratory |
we reexamine the simplified dark matter (dm) models with fermionic dm particle and spin-0 mediator. the dm-nucleon scattering cross sections in these models are low-momentum suppressed at tree-level, but receive sizable loop-induced spin-independent contribution. we perform one-loop calculations for scalar-type and twist-2 dm-quark operators, and complete two-loop calculations for scalar-type dm-gluon operator. analyzing the loop-level contribution from new operators, we find that future direct detection experiments could be sensitive to a fraction of the parameter space. the indirect detection and collider search also provide complementary constraints on these models. | simplified dark matter models with loop effects in direct detection and the constraints from indirect detection and collider search |
although they do not address the hierarchy problem, models with universal extra dimensions have attracted a lot of attention as simple benchmark models characterized by small mass splittings and a dark matter (dm) wimp played by the lightest kaluza-klein particle (lkp). we review their status, with emphasis on minimal implementation in five dimensions (mued) in which the lkp is a massive hypercharge gauge boson. in this case, the mass range accounting for the correct dm abundance (around 1.4 tev) remains untouched by lhc8 and is out of reach of present dm direct detection experiments. however, lhc14 can probe the relevant region in the 3-lepton channel. | status report on universal extra dimensions after lhc8 |
direct detection bounds are beginning to constrain a very simple model of weakly interacting dark matter—a majorana fermion with a coupling to the z boson. in a particularly straightforward gauge-invariant realization, this coupling is introduced via a higher-dimensional operator. while attractive in its simplicity, this model generically induces a large ρ parameter. an ultraviolet completion that avoids an overly large contribution to ρ is the singlet-doublet model. we revisit this model, focusing on the higgs blind spot region of parameter space where spin-independent interactions are absent. this model successfully reproduces dark matter with direct detection mediated by the z boson but whose cosmology may depend on additional couplings and states. future direct detection experiments should effectively probe a significant portion of this parameter space, aside from a small coannihilating region. as such, z -mediated thermal dark matter as realized in the singlet-doublet model represents an interesting target for future searches. | z boson mediated dark matter beyond the effective theory |
this paper describes the design, fabrication, commissioning and use of a calibration source insertion system (calis) in the darkside-50 direct dark matter search experiment. calis deploys radioactive sources into the liquid scintillator veto to characterize the detector response and detection efficiency of the darkside-50 liquid argon time projection chamber, and the surrounding 30 t organic liquid scintillator neutron veto. it was commissioned in september 2014 and has been used successfully in several gamma and neutron source campaigns since then. a description of the hardware and an excerpt of calibration analysis results are given below. | calis—a calibration insertion system for the darkside-50 dark matter search experiment |
liquid xenon-based direct detection dark matter experiments have recently expanded their searches to include high-energy nuclear recoil events as motivated by effective field theory dark matter and inelastic dark matter interaction models, but few xenon recoil calibrations above 100 kev are currently available. in this work, we measured the scintillation and ionization yields of xenon recoils up to 426 kev. the experiment uses 14.1 mev neutrons to scatter off xenon in a compact liquid xenon time projection chamber and produce quasimonoenergetic xenon recoils between 39 and 426 kev. we report the xenon recoil responses and their electric field dependence for recoil energies up to 306 kev; due to the low event statistics and the relatively mild field dependence, the yield values at higher energies are reported as the average of xenon responses for electric fields between 0.2 and 2.0 kv /cm . this result will enable xenon-based dark matter experiments to significantly increase their high-energy dark matter sensitivities by including energy regions that were previously inaccessible due to lack of calibrations. | calibrating the scintillation and ionization responses of xenon recoils for high-energy dark matter searches |
dual-phase liquid xenon (lxe) detectors lead the direct search for particle dark matter. understanding the signal production process of nuclear recoils in lxe is essential for the interpretation of lxe based dark matter searches. up to now, only two experiments have simultaneously measured both the light and charge yield at different electric fields, neither of which attempted to evaluate the processes leading to light and charge production. in this paper, results from a neutron calibration of liquid xenon with simultaneous light and charge detection are presented for nuclear recoil energies from 3-74 kev, at electric fields of 0.19, 0.49, and 1.02 kv /cm . no significant field dependence of the yields is observed. | simultaneous measurement of the light and charge response of liquid xenon to low-energy nuclear recoils at multiple electric fields |
we explore the possibility of using superfluid helium for direct detection of sub-gev dark matter (dm). we discuss the relevant phenomenology resulting from the scattering of an incident dark matter particle on a helium nucleus. rather than directly exciting quasi-particles, dm in this mass range will interact with a single he atom, triggering an atomic cascade which eventually also includes emission and thermalization of quasi-particles. we present in detail the analytical framework needed for modeling these processes and determining the resulting flux of quasi-particles. we propose a novel method for detecting this flux with modern force-sensitive devices, such as nanoelectro-mechanical system (nems) oscillators, and derive the sensitivity projections for a generic sub-gev dm detection experiment using such sensors. | signatures and detection prospects for sub-gev dark matter with superfluid helium |
at cosmic dawn, the 21 cm signal from intergalactic hydrogen was driven by ly-α photons from some of the earliest stars, producing a spatial pattern that reflected the distribution of galaxies at that time. due to the large foreground, it is thought that at around redshift 20 it is only observationally feasible to detect 21 cm fluctuations statistically, yielding a limited indirect probe of early galaxies. here, we show that 21 cm images at cosmic dawn should actually be dominated by large (tens of comoving megaparsecs) high-contrast bubbles surrounding individual galaxies. we demonstrate this using a substantially upgraded seminumerical simulation code that realistically captures the formation and 21 cm effects of the small galaxies expected during this era. small number statistics associated with the rarity of early galaxies, combined with the multiple scattering of photons in the blue wing of the ly-α line, create the large bubbles, and also enhance the 21 cm power spectrum by a factor of 2-7 and add to it a feature that measures the typical brightness of galaxies. these various signatures of discrete early galaxies are potentially detectable with planned experiments, such as the square kilometer array and the hydrogen epoch of reionization array, even if the early stars prove to be formed in dark matter halos with masses as low as 108 m ⊙, 10,000 times smaller than the milky way halo. | mapping discrete galaxies at cosmic dawn with 21 cm observations |
if dark matter has spin 0, only two wimp-nucleon interaction operators can arise as leading operators from the nonrelativistic reduction of renormalizable single-mediator models for dark matter-quark interactions. based on this crucial observation, we show that about 100 signal events at next generation directional detection experiments can be enough to enable a 2 σ rejection of the spin 0 dark matter hypothesis in favor of alternative hypotheses where the dark matter particle has spin 1 /2 or 1. in this context, directional sensitivity is crucial since anisotropy patterns in the sphere of nuclear recoil directions depend on the spin of the dark matter particle. for comparison, about 100 signal events are expected in a cf4 detector operating at a pressure of 30 torr with an exposure of approximately 26,000 cubic-meter-detector days for wimps of 100 gev mass and a wimp-fluorine scattering cross section of 0.25 pb. comparable exposures require an array of cubic meter time projection chamber detectors. | dark matter spin determination with directional direct detection experiments |
grand unified theories (gut) offer an elegant and unified description of electromagnetic, weak and strong interactions at high energy scales. a phenomenological and exciting possibility to grasp gut is to search for tev scale observables arising from abelian groups embedded in gut constructions. that said, we use dilepton data (ee and μμ) that has been proven to be a golden channel for a wide variety of new phenomena expected in theories beyond the standard model to probe gut-inspired models. since heavy dilepton resonances feature high signal selection efficiencies and relatively well-understood backgrounds, stringent and reliable bounds can be placed on the mass of the z‧ gauge boson arising in such theories. in this work, we obtain 95% c.l. limits on the z‧ mass for several gut-models using current and future proton-proton colliders with √{ s} = 13 tev , 33 tev ,and 100 tev, and put them into perspective with dark matter searches in light of the next generation of direct detection experiments. | gut models at current and future hadron colliders and implications to dark matter searches |
measurement of the local dark matter density plays an important role in both galactic dynamics and dark matter direct detection experiments. however, the estimated values from previous works are far from agreeing with each other. in this work, we provide a well-defined observed sample with 1427 g- and k-type main-sequence stars from the large sky area multi-object fibre spectroscopic telescope spectroscopic survey, taking into account selection effects, volume completeness, and the stellar populations. we apply a vertical jeans equation method containing a single exponential stellar disc, a razor thin gas disc, and a constant dark matter density distribution to the sample, and obtain a total surface mass density of 78.7 ^{+3.9}_{-4.7} m_{{⊙}} pc^{-2} up to 1 kpc and a local dark matter density of 0.018± 0.0054 m_{{⊙}} pc^{-3}. we find that the sampling density (i.e. number of stars per unit volume) of the spectroscopic data contributes to about two-third of the uncertainty in the estimated values. we discuss the effect of the tilt term in the jeans equation and find it has little impact on our measurement. other issues, such as a non-equilibrium component due to perturbations and contamination by the thick-disc population, are also discussed. | determining the local dark matter density with lamost data |
models incorporating flavoured dark matter provide an elegant solution to the dark matter problem, evading the tight lhc and direct direction constraints on simple wimp models. in dark minimal flavour violation, a simple framework of flavoured dark matter with new sources of flavour violation, the constraints from thermal freeze-out, direct detection experiments, and flavour physics create well-defined benchmark scenarios for these models. we study the lhc phenomenology of four such scenarios, focusing on final states where a single top quark is produced accompanied by no jets, one jet from the fragmentation of light quarks or a b-tagged jet. for each of these signatures we develop a realistic lhc analysis, and we show that the proposed analyses would increase the parameter space coverage for the four benchmarks, compared to existing flavour-conserving lhc analyses. finally we show the projected discovery potential of the considered signatures for the full lhc statistics at 14 tev, and for the high luminosity lhc. | single-top final states as a probe of top-flavoured dark matter models at the lhc |
we present a nonperturbative calculation of the strangeness of the nucleon yn within the framework of lattice qcd. this observable is known to be an important cornerstone to interpret results from direct dark matter detection experiments. we perform a lattice computation for yn with an analysis of systematic effects originating from discretization, finite size, chiral extrapolation and excited state effects leading to the value of yn=0.173 (50 ) . the rather large uncertainty of this value of yn is dominated by systematic uncertainties which we are able to quantify in this work. | strangeness of the nucleon from lattice qcd |
the search for dark matter is one of the main science drivers of the particle and astroparticle physics communities. determining the nature of dark matter will require a broad approach, with a range of experiments pursuing different experimental hypotheses. within this search program, collider experiments provide insights on dark matter which are complementary to direct/indirect detection experiments and to astrophysical evidence. to compare results from a wide variety of experiments, a common theoretical framework is required. the atlas and cms experiments have adopted a set of simplified models which introduce two new particles, a dark matter particle and a mediator, and whose interaction strengths are set by the couplings of the mediator. so far, the presentation of lhc and future hadron collider results has focused on four benchmark scenarios with specific coupling values within these simplified models. in this work, we describe ways to extend those four benchmark scenarios to arbitrary couplings, and release the corresponding code for use in further studies. this will allow for more straightforward comparison of collider searches to accelerator experiments that are sensitive to smaller couplings, such as those for the us community study on the future of particle physics (snowmass 2021), and will give a more complete picture of the coupling dependence of dark matter collider searches when compared to direct and indirect detection searches. by using semi-analytical methods to rescale collider limits, we drastically reduce the computing resources needed relative to traditional approaches based on the generation of additional simulated signal samples. | displaying dark matter constraints from colliders with varying simplified model parameters |
the scattering of dark matter particles off nuclei in direct detection experiments can be described in terms of a multidimensional effective field theory (eft). a new systematic analysis technique is developed using the eft approach and bayesian inference methods to exploit, when possible, the energy-dependent information of the detected events, experimental efficiencies, and backgrounds. highly dimensional likelihoods are calculated over the mass of the weakly interacting massive particle (wimp) and multiple eft coupling coefficients, which can then be used to set limits on these parameters and choose models (eft operators) that best fit the direct detection data. expanding the parameter space beyond the standard spin-independent isoscalar cross section and wimp mass reduces tensions between previously published experiments. combining these experiments to form a single joint likelihood leads to stronger limits than when each experiment is considered on its own. simulations using two nonstandard operators (o3 and o8 ) are used to test the proposed analysis technique in up to five dimensions and demonstrate the importance of using multiple likelihood projections when determining constraints on wimp mass and eft coupling coefficients. in particular, this shows that an explicit momentum dependence in dark matter scattering can be identified. | multidimensional effective field theory analysis for direct detection of dark matter |
light electroweakinos, the neutral and charged fermionic supersymmetric partners of the standard model su (2 )×u (1 ) gauge bosons and of the two su(2) higgs doublets, are an important target for searches for new physics with the large hadron collider (lhc). however, if the lightest neutralino is the dark matter, constraints from direct dark matter detection experiments rule out large swaths of the parameter space accessible to the lhc, including in large part the so-called "well-tempered" neutralinos. we focus on the minimal supersymmetric standard model (mssm) and explore in detail which regions of parameter space are not excluded by null results from direct dark matter detection, assuming exclusive thermal production of neutralinos in the early universe, and illustrate the complementarity with current and future lhc searches for electroweak gauginos. we consider both bino-higgsino and bino-wino "not-so-well-tempered" neutralinos, i.e. we include models where the lightest neutralino constitutes only part of the cosmological dark matter, with the consequent suppression of the constraints from direct and indirect dark matter searches. | not-so-well-tempered neutralino |
sub-gev mass dark matter particles whose collisions with nuclei would not deposit sufficient energy to be detected, could instead be revealed through their interaction with electrons. analyses of data from direct detection experiments usually require assuming a local dark matter halo velocity distribution. in the halo-independent analysis method, properties of this distribution are instead inferred from direct dark matter detection data, which allows then to compare different data without making any assumption on the uncertain local dark halo characteristics. this method has so far been developed for and applied to dark matter scattering off nuclei. here we demonstrate how this analysis can be applied to scattering off electrons. | halo-independent analysis of direct dark matter detection through electron scattering |
we show that dark matter axions or axion-like particles (alp) induce spontaneously alternating electric currents in conductors along the external magnetic fields due to the (medium) axial anomaly, realizing the chiral magnetic effects. we propose a new experiment to measure this current to detect the dark matter axions or alp. these induced currents are the electron medium effects, directly proportional to the axion or alp coupling to electrons, which depends on their microscopic physics, and also suppressed by the fermi velocity. | detecting axion dark matter with chiral magnetic effects |
it has been suggested that several small-scale structure anomalies in λ cdm cosmology can be solved by strong self-interaction between dark matter particles. it was shown by braaten and hammer [phys. rev. d 88, 063511 (2013), 10.1103/physrevd.88.063511] that the presence of a near threshold s-wave resonance can make the scattering cross section at nonrelativistic speeds come close to saturating the unitarity bound. this can result in the formation of a stable bound state of two asymmetric dark matter particles (which we call darkonium). the work of laha and braaten [phys. rev. d, 89, 103510 (2014), 10.1103/physrevd.89.103510] studied the nuclear recoil energy spectrum in dark matter direct detection experiments due to this incident bound state. here we study the angular recoil spectrum and show that it is uniquely determined up to normalization by the s-wave scattering length. observing this angular recoil spectrum in a dark matter directional detection experiment will uniquely determine many of the low-energy properties of dark matter independent of the underlying dark matter microphysics. | directional detection of dark matter in universal bound states |
we analyze a simple extension of the standard model where the dark matter particle is a dirac fermion that is a mixture of a singlet and an s u (2 ) doublet. the model contains only four free parameters: the singlet and the doublet masses and two new yukawa couplings. direct detection bounds in this model are very strong and require the dark matter particle to be singletlike. as a result, its relic density has to be obtained via coannihilations with the doublet. we find that the dark matter mass should be below 750 gev, the singlet-doublet mass difference cannot exceed 9%, and direct detection experiments offer the best chance to probe this scenario. finally, we also show that this model can effectively arise in well-motivated extensions of the standard model. | singlet-doublet dirac dark matter |
while most scintillation-based dark matter experiments search for weakly interacting massive particles (wimps), a sub-gev wimp-like particle may also be detectable in these experiments. while dark matter of this type and scale would not leave appreciable nuclear recoil signals, it may instead induce ionization of atomic electrons. accurate modeling of the atomic wave functions is key to investigating this possibility, with incorrect treatment leading to a large suppression in the atomic excitation factors. we have calculated these atomic factors for argon, krypton, and xenon and present the tabulated results for use with a range of dark matter models. this is made possible by the separability of the atomic and dark matter form factor, allowing the atomic factors to be calculated for general couplings; we include tables for vector, scalar, pseudovector, and pseudoscalar electron couplings. additionally, we calculate electron-impact total ionization cross sections for xenon using the tabulated results as a test of accuracy. lastly, we provide an example calculation of the event rate for dark matter scattering on electrons in xenon1t and show that these calculations depend heavily on how the low-energy response of the detector is modeled. | accurate electron-recoil ionization factors for dark matter direct detection in xenon, krypton, and argon |
the dark matter particle explorer (dampe) is a space high-energy cosmic-ray detector covering a wide energy band with a high energy resolution. one of the key scientific goals of dampe is to carry out indirect detection of dark matter by searching for high-energy gamma-ray line structure. to promote the sensitivity of gamma-ray line search with dampe, it is crucial to improve the acceptance and energy resolution of gamma-ray photons. in this paper, we quantitatively proved that the photon sample with the largest ratio of acceptance to energy resolution is optimal for line search. we therefore developed a line-search sample specifically optimized for the line-search. meanwhile, in order to increase the statistics, we also selected the so-called bgo-only photons that convert into e+e− pairs only in the bgo calorimeter. the standard, the line-search, and the bgo-only photon samples are then tested for line-search individually and collectively. the results show that a significantly improved limit could be obtained from an appropriate combination of the date sets, and the increase is about 20% for the highest case compared with using the standard sample only. | optimal gamma-ray selections for monochromatic line searches with dampe |
two photo-neutron sources, 88y 9be and 124sb 9be, have been used to investigate the ionization yield of nuclear recoils in the cdmslite germanium detectors by the supercdms collaboration. this work evaluates the yield for nuclear recoil energies between 1 and 7 kev at a temperature of ∼ 50 mk . we use a geant4 simulation to model the neutron spectrum assuming a charge yield model that is a generalization of the standard lindhard model and consists of two energy dependent parameters. we perform a likelihood analysis using the simulated neutron spectrum, modeled background, and experimental data to obtain the best fit values of the yield model. the ionization yield between recoil energies of 1 and 7 kev is shown to be significantly lower than predicted by the standard lindhard model for germanium. there is a general lack of agreement among different experiments using a variety of techniques studying the low energy range of the nuclear recoil yield, which is most critical for interpretation of direct dark matter searches. this suggests complexity in the physical process that many direct detection experiments use to model their primary signal detection mechanism and highlights the need for further studies to clarify underlying systematic effects that have not been well understood up to this point. | ionization yield measurement in a germanium cdmslite detector using photo-neutron sources |
we propose a test based on direct detection data that allows us to determine if the dark matter particle is different from its antiparticle. the test requires the precise measurement of the dark matter spin-independent direct detection cross sections off three different nuclei and consists of interpreting such signals in terms of self-conjugate (particle=antiparticle) dark matter to see if such interpretation is consistent. if it is not, the dark matter must be different from its antiparticle. we illustrate this procedure for two sets of target nuclei, {xe ,ar ,si } and {xe ,ar ,ge } , identifying the regions of the parameter space where it is particularly feasible. our results indicate that future signals in direct detection experiments, if sufficiently accurate, might be used to establish that the dark matter particle is not its own antiparticle—a major step towards the determination of the fundamental nature of the dark matter. | is the dark matter particle its own antiparticle? |
we present the first search for a dark matter annual modulation signal in the southern hemisphere conducted with nai(tl) detectors, performed by the dm-ice17 experiment. nuclear recoils from dark matter interactions are expected to yield an annually modulated signal independent of location within the earth's hemispheres. dm-ice17, the first step in the dm-ice experimental program, consists of 17 kg of nai(tl) located at the south pole under 2200 m.w.e. overburden of antarctic glacial ice. taken over 3.6 years for a total exposure of 60.8 kg yr, dm-ice17 data are consistent with no modulation in the energy range of 4-20 kev, providing the strongest limits on weakly interacting massive particle dark matter from a direct detection experiment located in the southern hemisphere. the successful deployment and stable long-term operation of dm-ice17 establishes the south pole ice as a viable location for future dark matter searches and in particular for a high-sensitivity nai(tl) dark matter experiment to directly test the dama/libra claim of the observation of dark matter. | first search for a dark matter annual modulation signal with nai(tl) in the southern hemisphere by dm-ice17 |
dark matter that interacts strongly with baryons can avoid the stringent dark matter direct detection constraints, because, like baryons, they are likely to be absorbed when traversing the rocks, leading to a suppressed flux in deep underground labs. such strongly interacting dark matter, however, can be probed by dark matter experiments or other experiments operated on the ground level or in the atmosphere. in this paper we carry out systematic analysis of two of these experiments, xqc and csr, to compute the experimental constraints on the strongly interacting dark matter in the following three scenarios: (1) spin-independent and spin-dependent interactions; (2) different velocity dependent cross sections; (3) different dark matter mass fractions. some of the scenarios are first analyzed in the literature. we find that the xqc exclusion region has some non-trivial dependencies on the various parameters and the limits in the spin-dependent case is quite different from the spin-independent case. a peculiar region in the parameter space, where the xqc constraint disappears, is also found in our monte carlo simulations. this occurs in the case where the interaction cross section is proportional to the square of the velocity. we further compare our xqc and csr limits to other experimental constraints, and find that a large parameter space is allowed by various experiments if the dark matter mass fraction is sufficiently small, fχ ≲ 10-4. | xqc and csr constraints on strongly interacting dark matter with spin and velocity dependent cross sections |
as experimental null results increase the pressure on heavy weakly interacting massive particles (wimps) as an explanation of thermal dark matter (dm), it seems timely to explore previously overlooked regions of the wimp parameter space. in this work we extend the minimal gauged $u(1)_{l_\mu-l_\tau}$ model studied in \cite{bauer:2018onh} by a light (mev-scale) vector-like fermion $\chi$. taking into account constraints from cosmology, direct and indirect detection we find that the standard benchmark of $m_v=3 m_\chi$ for dm coupled to a vector mediator is firmly ruled out for unit dm charges. however, exploring the near-resonance region $m_v\gtrsim 2 m_\chi$ we find that this model can simultaneously explain the dm relic abundance $\omega h^2 =0.12$ and the $(g-2)_\mu$ anomaly. allowing for small charge hierarchies of $\lesssim\mathcal{o}(10)$, we identify a second window of parameter space in the few-gev region, where $\chi$ can account for the full dm relic density. | let there be light dark matter: the gauged $u(1)_{l_\\mu-l_\\tau}$ case |
we study the experimental signatures of top flavored dark matter (top fdm) in direct detection searches and at the lhc. we show that for a dark matter mass above 200 gev, top fdm can be consistent with current bounds from direct detection experiments and relic abundance constraints. we also show that next generation direct detection experiments will be able to exclude the entire perturbative parameter region for top fdm. for regions of parameter space where the flavor partners of top fdm are not readily produced, the lhc signatures of top fdm are similar to those of other models previously studied in the literature. for the case when the flavor partners are produced at the lhc, we study their impact on a search based on transverse mass variables and find that they diminish the signal significance. however, when the dm flavor partners are split in mass by less than 120-130 gev, the lhc phenomenology becomes very distinctive through the appearance of displaced vertices. we also propose a strategy by which all parameters of the underlying model can be experimentally determined when the flavor partners can be observed. | signatures of top flavored dark matter |
the discovery of argon from deep underground sources with significantly less 39ar than atmospheric argon was an important step in the development of direct dark matter detection experiments using argon as the active target. we report on the design and operation of a low-background single-phase liquid argon detector that was built to study the 39ar content of this underground argon. underground argon from the kinder morgan co2 plant in cortez, colorado was determined to have less than 0.65% of the 39ar activity in atmospheric argon, or 6.6 mbq/kg specific 39ar activity. | a study of the trace 39ar content in argon from deep underground sources |
the simplest higgs-portal dark matter model is studied in the light of dark matter self-interacting effects on the formation of large scale structures. we show the direct detection limits in both the resonant and large mass region. finally, we also compare these limits with those at the lhc and xenon 1t experiments. | higgs-portal scalar dark matter: scattering cross section and observable limits |
supersymmetric extensions of the standard model with scalar superpartners above 10 tev are well motivated since the higgs boson mass can be explained by quantum corrections while maintaining gauge coupling unification. if supersymmetry breaking is transmitted to gauginos via anomaly mediation, the gaugino masses are loop suppressed compared to scalar masses, and the lightest supersymmetric particle is the higgsino or wino, which can be the dark matter. in this setup, we identify the regions of parameter space that reproduce the observed higgs boson mass and the thermal abundance of dark matter. we analyze the effects of complex phases in the gaugino mass parameters on the electron electric dipole moment (edm) and the dark matter scattering cross section. we find that, for scalar masses up to 10 pev and any size of the complex phases, the model with higgsino dark matter is within reach of planned experiments—advanced acme via electron edm and lux-zeplin via dark matter direct detection—with complementary discovery potentials, and the model with wino dark matter is within reach of future electron edm experiments. | discovery potential for split supersymmetry with thermal dark matter |
we investigate a model with two real scalar fields that minimally generates exponentially different scales in an analog of the coleman-weinberg mechanism. the classical scale invariance — the absence of dimensionful parameters in the tree-level action, required in such a scale generation — can naturally be understood as a special case of the multicritical-point principle. this two-scalar model can couple to the standard model higgs field to realize a maximum multicriticality (with all the dimensionful parameters being tuned to critical values) for field values around the electroweak scale, providing a generalization of the classical scale invariance to a wider class of criticality. as a bonus, one of the two scalars can be identified as higgs-portal dark matter. we find that this model can be consistent with the constraints from dark matter relic abundance, its direct detection experiments, and the latest lhc data, while keeping the perturbativity up to the reduced planck scale. we then present successful benchmark points satisfying all these constraints: the mass of dark matter is a few tev, and its scattering cross section with nuclei is of the order of 10-9 pb, reachable in near future experiments. the mass of extra higgs boson h is smaller than or of the order of 100 gev, and the cross section of e+e- → zh can be of fb level for collision energy 250 gev, targetted at future lepton colliders. | dark matter in minimal dimensional transmutation with multicritical-point principle |
we review the recent status of big bounce genesis as a new possibility of using dark matter particles' mass and interaction cross-section to test the existence of a bounce universe at the early stage of evolution in our currently-observed universe. to study the dark matter production and evolution inside the bounce universe, called big bounce genesis for short, we propose a model independent approach. we shall present the motivation for proposing big bounce, as well as the model independent predictions, which can be tested by dark matter direct searches. a positive finding shall have profound impact on our understanding of the early universe physics. | big bounce genesis and possible experimental tests: a brief review |
we explore the potential of future cryogenic direct detection experiments to determine the properties of the mediator that communicates the interactions between dark matter and nuclei. due to their low thresholds and large exposures, experiments like cresst-iii, supercdms snolab and edelweiss-iii will have excellent capability to reconstruct mediator masses in the mev range for a large class of models. combining the information from several experiments further improves the parameter reconstruction, even when taking into account additional nuisance parameters related to background uncertainties and the dark matter velocity distribution. these observations may offer the intriguing possibility of studying dark matter self-interactions with direct detection experiments. | exploring light mediators with low-threshold direct detection experiments |
in the presence of a real singlet scalar field with z2 symmetry in addition to the higgs field in the standard model, we analytically investigate all possible one-step and two-step electroweak phase transitions (ewpt) in the high-temperature expansion limit. in particular, we examine the possibility of a first-order phase transition in an intermediate temperature interval of the universe for two-step scenarios. in all scenarios, we provide with necessary conditions on the parameters of the model to address a first- or second-order phase transition if ever possible in the high-temperature approximation. we show that among all possible ewpt channels in this model, only the two-step phase transition (0 , 0) →(0 , w) →(v , 0) can be of first-order type, either in the first or second step. the conditions obtained for ewpt is confronted with the dark matter (dm) and collider constraints. it is shown that the second-order one-step (0 , 0) →(v , 0) scenario can evade the dm constraints, but it is not accessible to future colliders. the two-step first-order ewpt scenario (0 , 0) →(0 , w) →(v , 0) , except for small dm masses, is excluded by direct detection experiments xenon1t/lux, but it is accessible in future colliders ilc/tlep. | vacuum structure and electroweak phase transition in singlet scalar dark matter |
the dark axion portal provides a model for dark matter (dm) in which both dark photons $\gamma^\prime$ and axions $a$ can contribute to the present day abundance of dm. we study the parameter space of the dark axion portal to pinpoint regions of the parameter space where $\gamma^\prime$ and $a$ can be produced with sufficient abundance to account for the cosmic dm density, while still being detectable in planned direct detection and axion haloscope experiments. in particular, we explore the production of ev-scale dark photons in the dark axion portal, taking into account a possible kinetic mixing between the dark and visible photons, which is essential for the detection of dark photons through absorption in direct searches. we show that a non-zero kinetic mixing does not generally spoil the phenomenology of the model, leaving both the axion and dark photon stable. viable production mechanisms point to a sub-dominant population of dark photons making up $\lesssim 10\%$ of the dm, with the remainder consisting of axion dm. dark photons in the mass range $m_{\gamma^\prime} \sim 20-200\,\mathrm{ev}$ and axions in the mass range $m_a \sim 30 - 400\,\mu\mathrm{ev}$ may be produced with these abundances self-consistently in the dark axion portal and are within the reach of future direct searches. | cosmology and direct detection of the dark axion portal |
we present a class of models in which dark matter (dm) is a fermionic singlet under the standard model (sm) gauge group but is charged under a symmetry of flavor that acts as well on the sm fermions. interactions between dm and sm particles are mediated by the scalar fields that spontaneously break the flavor symmetry, the so-called flavons. in the case of gauged flavor symmetries, the interactions are also mediated by the flavor gauge bosons. we first discuss the construction and the generic features of this class of models. then a concrete example with an abelian flavor symmetry is considered. we compute the complementary constraints from the relic abundance, direct detection experiments and flavor observables, showing that wide portions of the parameter space are still viable. other possibilities like non-abelian flavor symmetries can be analyzed within the same framework. | flavor portal to dark matter |
the interpretation of dark matter direct detection experiments is complicated by the fact that neither the astrophysical distribution of dark matter nor the properties of its particle physics interactions with nuclei are known in detail. to address both of these issues in a very general way we develop a new framework that combines the full formalism of non-relativistic effective interactions with state-of-the-art halo-independent methods. this approach makes it possible to analyse direct detection experiments for arbitrary dark matter interactions and quantify the goodness-of-fit independent of astrophysical uncertainties. we employ this method in order to demonstrate that the degeneracy between astrophysical uncertainties and particle physics unknowns is not complete. certain models can be distinguished in a halo-independent way using a single ton-scale experiment based on liquid xenon, while other models are indistinguishable with a single experiment but can be separated using combined information from several target elements. | studying generalised dark matter interactions with extended halo-independent methods |
the existence of dark matter and dark energy in cosmology is implied by various observations, however, they are still unclear because they have not been directly detected. in this letter, an unified model of dark energy and dark matter that can explain the evolution history of the universe later than inflationary era, the time evolution of the growth rate function of the matter density contrast, the flat rotation curves of the spiral galaxies, and the gravitational experiments in the solar system is proposed in mimetic matter model. | unified description of dark energy and dark matter in mimetic matter model |
the evidence of environmental dependence of sn ia luminosity has inspired recent discussion about whether the late-universe cosmic acceleration is still supported by supernova data. we adopt the δhr/δage parameter, which describes the dependence of supernova absolute magnitude on the age of supernova progenitor, as an additional nuisance parameter. using the pantheon supernova data, a lower bound ≥12 gyr on the cosmic age, and a gaussian prior h0=70± 2 km s-1 mpc-1 on the hubble constant, we reconstruct the cosmic expansion history. within the flat λ cold dark matter framework, we still find a 5.6σ detection of cosmic acceleration. this is because a matter-dominated decelerating universe would be too young to accommodate observed old stars with age ≳12 gyr. a decelerating but non-flat universe is marginally consistent with the data, however, only in the presence of a negative spatial curvature ∼2 orders of magnitude beyond the current constraint from cosmic microwave background data. finally, we propose a more general parameterization based on the cosmic age (page), which is not directly tied to the dark energy concept and hence is ideal for a null test of the cosmic acceleration. we find that, for a magnitude evolution rate δhr/δage ≲ 0.3 mag/5.3 gyr, a spatially flat and decelerating page universe is fully consistent with the supernova data and the cosmic age bound, and has no tension with the geometric constraint from the observed cosmic microwave background acoustic angular scales. | supernova magnitude evolution and page approximation |
we select a sample of milky way (mw) mass haloes from a high-resolution version of the eagle simulation to study their inner dark matter (dm) content and how baryons alter it. as in previous studies, we find that all haloes are more massive at the centre compared to their dark matter-only (dmo) counterparts at the present day as a result of the dissipational collapse of baryons during the assembly of the galaxy. however, we identify two processes that can reduce the central halo mass during the evolution of the galaxy. first, gas blowouts induced by active galactic nuclei feedback can lead to a substantial decrease of the central dm mass. secondly, the formation of a stellar bar and its interaction with the dm can induce a secular expansion of the halo; the rate at which dm is evacuated from the central region by this process is related to the average bar strength, and the time-scale on which it acts determines how much the halo has decontracted. although the inner regions of the haloes we have investigated are still more massive than their dmo counterparts at z = 0, they are significantly less massive than in the past and less massive than expected from the classic adiabatic contraction model. since the mw has both a central supermassive black hole and a bar, the extent to which its halo has contracted is uncertain. this may affect estimates of the mass of the mw halo and of the expected signals in direct and indirect dm detection experiments. | baryon-driven decontraction in milky way-mass haloes |
we propose a minimal dark matter (mdm) scenario in the context of a simple gauge-higgs unification (ghu) model based on the gauge group s u (3 )×u (1 )' in five-dimensional minkowski space with a compactification of the fifth dimension on the 1s/z2 orbifold. a pair of vectorlike s u (3 ) multiplet fermions in a higher-dimensional representation is introduced in the bulk, and the dm particle is identified with the lightest mass eigenstate among the components in the multiplets. in the original model description, the dm particle communicates with the standard model (sm) particles only through the bulk gauge interaction, and hence our model is the ghu version of the mdm scenario. there are two typical realizations of the dm particle in four-dimensional effective theory: (i) the dm particle is mostly composed of the sm s u (2 )l multiplets, or (ii) the dm is mostly composed of the sm s u (2 )l singlets. since the case (i) is very similar to the original mdm scenario, we focus on the case (ii), which is a realization of the higgs-portal dm scenario in the context of the ghu model. we identify an allowed parameter region to be consistent with the current experimental constraints, which will be fully covered by the direct dark matter detection experiments in the near future. in the presence of the bulk multiplet fermions in higher-dimensional s u (3 ) representations, we reproduce the 125 gev higgs boson mass through the renormalization group evolution of higgs quartic coupling with the compactification scale of 10-100 tev. | fermionic minimal dark matter in 5d gauge-higgs unification |
the nature of dark matter (dm) and how it may interact with the various fields of the standard model (sm) remains a mystery. in this paper we show that the interaction between new light dark matter mediators and the sm particles can be naturally suppressed if one employs a single, flat extra dimension (ed). in this setup, the sm fields are localized in a finite width `fat' brane, similar to models of universal extra dimensions (ued), while dm, in turn, is confined to a thin brane at the opposite end of the ed interval. including brane localized kinetic terms on the fat brane for the mediator fields, the resulting coupling between the sm and these light mediators can be several orders of magnitude smaller than the corresponding ones between the mediators and dm which we assume to be a typical gauge coupling. we investigate the implications of this scenario for both vector ( i.e, dark photon, dp) and scalar mediator fields in the 5-d bulk. in this setup kinetic mixing, which is usually employed to suppress light mediator couplings, is not required. here we assume that the sm particles couple to the dp via their b - l charges while the dp couples to the dm via a dark charge. both the vector dp couplings and the corresponding higgs portal couplings with the sm are shown to be natural small in magnitude with a size dependent on ratio of the 5-d compactification radius, r -1 ∼ 0 .1-1 gev, and the sm brane thickness, l -1 ∼ 2-10 tev, a range chosen to avoid lhc and other experimental constraints. in this framework one can obtain the observed value of the dm relic abundance for a wide range of parameter choices, while the constrains due to direct dm detection and the invisible width of the higgs do not impose significant challenges to the model. finally, this mechanism can lead to distinct signatures in both present and upcoming experiments as it combines some common features of ued and dp models in a single ed setup. | thick branes in extra dimensions and suppressed dark couplings |
we point out that the direct detection of dark matter via its electro-magnetic polarizability is described by two new nuclear form factors, which are controlled by the 2-nucleon nuclear density. the signature manifests a peculiar dependence on the atomic and mass numbers of the target nuclei, as well as on the momentum transfer, and can differ significantly from experiment to experiment. we also discuss uv completions of our scenario. | direct detection of dark matter polarizability |
direct detection of light dark matter (dm), below the gev scale, through electron recoil can be efficient if dm has a velocity well above the virial value of v ∼10-3. we point out that if there is a long range attractive force sourced by bulk ordinary matter, i.e., baryons or electrons, dm can be accelerated towards the earth and reach velocities v ∼0.1 near the earth's surface. in this "attractive scenario," all dm will be boosted to high velocities by the time it reaches direct detection apparatuses in laboratories. furthermore, the attractive force leads to an enhanced dm number density at the earth, facilitating dm detection even more. we elucidate the implications of this scenario for electron recoil direct detection experiments and find parameters that could lead to potential signals, while being consistent with stellar cooling and other bounds. our scenario can potentially explain the recent excess in electron recoil signals reported by the xenon1t experiment in the ∼kev energy regime as well as the hint for nonstandard stellar cooling. | attractive scenario for light dark matter direct detection |
dual-phase xenon time projection chamber (tpc) detectors have demonstrated superior search sensitivities to dark matter over a wide range of particle masses. to extend their sensitivity to include low-mass dark matter interactions, it is critical to characterize both the light and charge responses of liquid xenon to sub-kev nuclear recoils. in this work, we report a new nuclear recoil calibration in the lux detector $\textit{in situ}$ using neutron events from a pulsed adelphi deuterium-deuterium neutron generator. we demonstrate direct measurements of light and charge yields down to 0.45 kev (1.4 scintillation photons) and 0.27 kev (1.3 ionization electrons), respectively, approaching the physical limit of liquid xenon detectors. we discuss the implication of these new measurements on the physics reach of dual-phase xenon tpcs for nuclear-recoil-based low-mass dark matter detection. | improved dark matter search sensitivity resulting from lux low-energy nuclear recoil calibration |
we study the effects of inelastic dark matter (dm) self-interactions on the internal structure of a simulated milky way (mw)-size halo. self-interacting dark matter (sidm) is an alternative to collisionless cold dark matter (cdm) which offers a unique solution to the problems encountered with cdm on sub-galactic scales. although previous sidm simulations have mainly considered elastic collisions, theoretical considerations motivate the existence of multistate dm where transitions from the excited to the ground state are exothermic. in this work, we consider a self-interacting, two-state dm model with inelastic collisions, implemented in the arepo code. we find that energy injection from inelastic self-interactions reduces the central density of the mw halo in a shorter time-scale relative to the elastic scale, resulting in a larger core size. inelastic collisions also isotropize the orbits, resulting in an overall lower velocity anisotropy for the inelastic mw halo. in the inner halo, the inelastic sidm case (minor-to-major axial ratio s ≡ c/a ≈ 0.65) is more spherical than the cdm (s ≈ 0.4), but less spherical than the elastic sidm case (s ≈ 0.75). the speed distribution f(v) of dm particles at the location of the sun in the inelastic sidm model shows a significant departure from the cdm model, with f(v) falling more steeply at high speeds. in addition, the velocity kicks imparted during inelastic collisions produce unbound high-speed particles with velocities up to 500 km s-1 throughout the halo. this implies that inelastic sidm can potentially leave distinct signatures in direct detection experiments, relative to elastic sidm and cdm. | the impact of inelastic self-interacting dark matter on the dark matter structure of a milky way halo |
the relative sensitivity of different direct detection experiments depends sensitively on the astrophysical distribution and particle physics nature of dark matter, prohibiting a model-independent comparison. the situation changes fundamentally if two experiments employ the same target material. we show that in this case one can compare measurements of an annual modulation and exclusion bounds on the total rate while making no assumptions on astrophysics and no (or only very general) assumptions on particle physics. in particular, we show that the dark matter interpretation of the dama/libra signal can be conclusively tested with cosinus, a future experiment employing the same target material. we find that if cosinus excludes a dark matter scattering rate of about 0.01 kg-1 days-1 with an energy threshold of 1.8 kev and resolution of 0.2 kev, it will rule out all explanations of dama/libra in terms of dark matter scattering off sodium and/or iodine. | model-independent comparison of annual modulation and total rate with direct detection experiments |
dark matter particles with masses in the sub-giga electron volt range have escaped severe constraints from direct detection experiments such as lux, pandax-ii, and xenon100, as the corresponding recoil energies are, largely, lower than the detector thresholds. in a companion paper, we demonstrated, in a model independent approach, that a significantly large fraction of the parameter space escapes the cosmological and astrophysical constraints. we show here, though, that the remaining parameter space lends itself to the possibility of discovery at both direct detection experiments (such as cresst-ii) as well as in a low-energy collider such as belle-ii. in examining the popular γ +φ φ* channel, we employ refined techniques that successfully overcome the detector lacunae to reach very high sensitivities. furthermore, the ℓ-ℓ++φ φ* channel is, for the first time, shown to have comparable or even higher sensitivity. | model independent analysis of mev scale dark matter. ii. implications from e-e+ colliders and direct detection |
we consider a class of b - τ yukawa unified supersymmetric (susy) su(5) guts, in which the asymptotic gaugino m 1,2,3 masses are generated through the mirage mediated supersymmetry breaking, which is a combination of the gravity and anomaly mediation. due to the contributions from the anomaly contribution, m 3 is always lighter than m 1 and m 2, and consequently for the range of asymptotic masses considered, the gluino mass {m}_{\tilde{g}} at low scale is bounded from above at about 4 tev. we realize two different regions, in one of which the mssm μ-term is less than about 3 tev. this region yields a stop mass up to 5 tev, and the stop mass is nearly degenerate with the lsp neutralino for mass around 0.8 to 1.7 tev. a stau mass can be realized up to about 5 tev, and the stau mass is approximately degenerate with the lsp neutralino for mass around 2 to 3 tev. in addition, an a-funnel solution with {m}_a≈ 2{m}_{{\tilde{χ}}_1^0} and {m}_{{\tilde{χ}}_1^0}∼ 700-900 gev is realized. these three cases yield lsp dark matter abundance in accordance with observations. a second region, on the other hand, arises for {m}_{\tilde{g}}≲ 1.1{m}_{{\tilde{χ}}_1^0} . the μ-term is rather large (≳20 tev), and the lsp neutralino is a bino-wino mixture. the gluino mass (∼ 0 .8-1 .2 tev) is nearly degenerate with the lsp neutralino mass and hence, the gluino-neutralino coannihilation processes play a role in reducing the relic abundance of lsp neutralino down to ranges allowed by the current wmap measurements. the two regions above can be distinguished through the direct detection experiments. the first region with relatively low μ values yields higgsino-like dm, whose scattering on the nucleus typically has a large cross-section. we find that such solutions are still allowed by the current results from the lux experiment, and they will be severely tested by the lux-zeplin (lz) experiment. the second region contains bino-wino dm whose scattering cross-section is relatively low. these solutions are harder to rule out in the foreseeable future. | b - τ yukawa unification in susy su(5) with mirage mediation: lhc and dark matter implications |
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