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dark matter (dm) direct detection experiments which are directionally-sensitive may be the only method of probing the full velocity distribution function (vdf) of the galactic dm halo. we present an angular basis for the dm vdf which can be used to parametrise the distribution in order to mitigate astrophysical uncertainties in future directional experiments and extract information about the dm halo. this basis consists of discretising the vdf in a series of angular bins, with the vdf being only a function of the dm speed v within each bin. in contrast to other methods, such as spherical harmonic expansions, the use of this basis allows us to guarantee that the resulting vdf is everywhere positive and therefore physical. we present a recipe for calculating the event rates corresponding to the discrete vdf for an arbitrary number of angular bins n and investigate the discretisation error which is introduced in this way. for smooth, standard halo model-like distribution functions, only n=3 angular bins are required to achieve an accuracy of around 01-30% in the number of events in each bin. shortly after confirmation of the dm origin of the signal with around 50 events, this accuracy should be sufficient to allow the discretised velocity distribution to be employed reliably. for more extreme vdfs (such as streams), the discretisation error is typically much larger, but can be improved with increasing n. this method paves the way towards an astrophysics-independent analysis framework for the directional detection of dark matter. | discretising the velocity distribution for directional dark matter experiments |
one trend in dark matter direct detection is the development of techniques which will lower experimental thresholds and achieve sensitivity to light mass dark matter particles. in doing so, it is necessary to have an understanding of the low energy spectrum of the major background components. geant4 has a number of specialized low energy physics processes that can be implemented when simulating an experimental geometry. to understand this low energy region for the super cryogenic dark matter search (supercdms), a variety of these models have been simulated and compared against theoretical calculations and supercdms calibration data. most of the low energy processes include a more complete description of the atomic structure, allowing us to observe the phenomenon of compton steps in the simulation. an important application of this low energy background modeling is for the supercdms low ionization threshold experiment (cdmslite). cdmslite has reached world-leading sensitivities in the search for low mass weakly interacting massive particle (wimp) dark matter. using neganov-trofinov-luke phonon amplification, cdmslite has achieved a threshold of less than 60 ev for electron recoils. the dark matter sensitivity of the cdmslite-soudan data can be improved by understanding and modeling the experimental backgrounds down to this threshold. development of the machinery for creating a low energy background model will also be useful in the future supercdms-snolab experiment which will run multiple high voltage detectors in cdmslite mode. | low energy background spectrum in cdmslite |
we study the compatibility of the observed dama modulation signal with inelastic scattering of dark matter (dm) off of the 0.1% thallium (tl) dopant in dama. in this work we test whether there exist regions of parameter space where the tl interpretation gives a good fit to the most recent data from dama, and whether these regions are compatible with the latest constraints from other direct detection experiments. previously, chang et al. in 2010 [1], had proposed the tl interpretation of the dama data, and more recently (in 2019) the dama/libra collaboration [2] found regions in parameter space of tl inelastic scattering that differ by more than 10σ from a no modulation hypothesis. we have expanded upon their work by testing whether the regions of parameter space where inelastic dm-tl scattering gives a good fit to the most recent dama data survive the constraints placed by the lack of a dm signal in xenon1t and cresst-ii. in addition, we have tested how these regions change with the main sources of uncertainty: the tl quenching factor, which has never been measured directly, and the astrophysical uncertainties in the dm distribution. we conclude that inelastic dm scattering off tl cannot explain the dama data in light of null results from other experiments. | inelastic dark matter scattering off thallium cannot save dama |
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-$\mu$m 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 <0.58 $\mu$bq/kg (<0.24 $\mu$bq/kg) and <0.26 $\mu$bq/kg (<0.11 $\mu$bq/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 |
detectors for direct dark matter search using noble gases in the liquid phase as a detection medium need to be coupled to liquefaction, purification and recirculation systems. a dedicated cryogenic system has been assembled and operated at the infn-naples cryogenic laboratory with the aim to liquefy and purify the argon used as an active target in liquid argon detectors to study the scintillation and ionization signals detected by large sipm arrays. the cryogenic system is mainly composed of a double wall cryostat hosting the detector, a purification stage to reduce the impurities below one part per billion level, a condenser to liquefy the argon, and a recirculation gas panel connected to the cryostat equipped with a custom gas pump. the main features of the cryogenic system are reported as well as the performance, long term operation and stability in terms of the most relevant thermodynamic parameters. | a versatile cryogenic system for liquid argon detectors |
cosinus (cryogenic observatory for signatures seen in next-generation underground searches) is an experiment employing cryogenic calorimeters, dedicated to direct dark matter search in underground laboratories. its goal is to cross-check the annual modulation signal the dama collaboration has been detecting for about 20 years (bernabei et al. in nucl part phys proc 303-305:74-79, 2018. 10.1016/j.nuclphysbps.2019.03.015) and which has been ruled out by other experiments in certain dark matter scenarios. cosinus can provide a model-independent test by the use of the same target material (nai), with the additional chance of discriminating β /γ events from nuclear recoils on an event-by-event basis, by the application of a well-established temperature sensor technology developed within the cresst collaboration. each module is constituted by two detectors: the light detector, that is a silicon beaker equipped with a transition edge sensor (tes), and the phonon detector, a small cubic nai crystal interfaced with a carrier of a harder material (e.g. cdwo4), also instrumented with a tes. this technology had so far never been applied to nai crystals because of several well-known obstacles, and cosinus is the first experiment which succeeded in operating nai crystals as cryogenic calorimeters. here, we present the cosinus project, describe the achievements and the challenges of the cosinus prototype development and discuss the status and the perspectives of this nai-based cryogenic frontier. | cosinus: cryogenic calorimeters for the direct dark matter search with nai crystals |
we study the dark matter (dm) direct detection for the models with the effects of the isospin-violating couplings, exothermic scatterings, and/or the lightness of the mediator, proposed to relax the tension between the cdms-si signals and null experiments. in the light of the new updates of the lux and cdmslite data, we find that many of the previous proposals are now ruled out, including the ge-phobic exothermic dm model and the xe-phobic dm one with a light mediator. we also examine the exothermic dm models with a light mediator but without the isospin violation, and we are unable to identify any available parameter space that could simultaneously satisfy all the experiments. the only models that can partially relax the inconsistencies are the xe-phobic exothermic dm models with or without a light mediator. but even in this case, a large portion of the cdms-si regions of interest has been constrained by the lux and supercdms data. | direct detection of exothermic dark matter with light mediator |
we study a model that extends the georgi-machacek model by the addition of an inert doublet, $\phi_2$. this allows for the model to contain a natural dark matter candidate, $h^0$. for a number of benchmark points at two dm candidate masses ($m_{h^0} \in \{70,\,250\}$ gev), we determine the relic abundance, direct detection cross section, and collider constraints. we find that the collider studies used do not constrain the model. for the parameter region chosen, the points are ruled out by direct detection experimental results. at the lower mass point, we do not find a viable parameter point, while at the higher mass we do find an additional point that satisfies all the applied constraints. | dark matter in the georgi-machacek model with an additional inert doublet |
open quantum systems with chiral interactions can be realized by coupling atoms to guided radiation modes in waveguides or optical fibres. in their steady state these systems can feature intricate many-body phases such as entangled dark states, but their detection and characterization remains a challenge. here we show how such collective phenomena can be uncovered through monitoring the record of photons emitted into the guided modes. this permits the identification of dark entangled states but furthermore offers novel capabilities for probing complex dynamical behavior, such as the coexistence of a dark entangled and a mixed phase. our results are of direct relevance for current experiments, as they provide a framework for probing, characterizing and classifying dynamical features of chiral light-matter systems. | dynamical creation and detection of entangled many-body states in a chiral atom chain |
the observed higgs signal at the large hadron collider (lhc) may be derived from the two mass-degenerate resonances. we investigate this scenario in the next-to-minimal supersymmetric standard model (nmssm) in which both the two lightest cp-even higgs bosons have masses around 125 gev. we perform a comprehensive scan over the parameters in the nmssm considering the current experimental constraints, especially the constraints from dark matter direct detection. the surviving samples are featured with relatively small μ and large tanβ . the samples with large deviation of double ratios have large mixing between doublet field and singlet field. | mass-degenerate higgs bosons near 125 gev in the nmssm under current experimental constraints |
experimental collaborations for the large hadron collider conducted various searches for supersymmetry. in the absence of signals, lower limits were put on sparticle masses but usually within frameworks with (over-)simplifications relative to the entire indications by supersymmetry models. for complementing current interpretations of experimental bounds, we introduce a 30-parameter version of the r-parity conserving minimal supersymmetric standard model (mssm-30). using a sample of the mssm-30 which are in harmony with cold dark matter, flavor and precision electroweak constraints, we explicitly show the prospects for assessing neutralino candidate dark matter in contrast to future searches for supersymmetry. the mssm-30-parameter regions that are beyond reach to dark matter direct detection experiments could be probed by future hadron-hadron colliders. | future prospects for the minimal supersymmetric standard model |
in this work we introduce rapidd, a surrogate model that speeds up the computation of the expected spectrum of dark matter particles in direct detection experiments. rapidd replaces the exact calculation of the dark matter differential rate (which in general involves up to three nested integrals) with a much faster parametrization in terms of ordinary polynomials of the dark matter mass and couplings, obtained in an initial training phase. in this article, we validate our surrogate model on the multi-dimensional parameter space resulting from the effective field theory description of dark matter interactions with nuclei, including also astrophysical uncertainties in the description of the dark matter halo. as a concrete example, we use this tool to study the complementarity of different targets to discriminate simplified dark matter models. we demonstrate that rapidd is fast and accurate, and particularly well-suited to explore a multi-dimensional parameter space, such as the one in effective field theory approach, and scans with a large number of evaluations. | surrogate models for direct dark matter detection |
in the absence of direct accelerator data to constrain particle models, and given existing astrophysical uncertainties associated with the phase space distribution of wimp dark matter in our galactic halo, extracting information on fundamental particle microphysics from possible signals in underground direct detectors will be challenging. given these challenges we explore the requirements for direct detection of dark matter experiments to extract information on fundamental particle physics interactions. in particular, using bayesian methods, we explore the quantitative distinctions that allow differentiation between different non-relativistic effective operators, as a function of the number of detected events, for a variety of possible operators that might generate the detected distribution. without a spinless target one cannot distinguish between spin-dependent and spin-independent interactions. in general, of order 50 events would be required to definitively determine that the fundamental dark matter scattering amplitude is momentum independent, even in the optimistic case of minimal detector backgrounds and no inelastic scattering contributions. this bound can be improved with reduced uncertainties in the dark matter velocity distribution. | extracting particle physics information from direct detection of dark matter with minimal assumptions |
we demonstrate that dark matter particles gravitationally bound to the earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. the new spectral feature that we predict can provide a complementary verification of dark matter discovery at experiments with positive signal but unclear background. the effect is generically expected, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section. | new spectral features from bound dark matter |
we present a new focus point supersymmetry-breaking scenario based on the supersymmetric e_7 nonlinear sigma model. in this model, squarks and sleptons are identified with (pseudo) nambu-goldstone bosons. their masses are generated only radiatively through gauge and yukawa interactions, and they are much smaller than the gravitino and gaugino masses at a high energy scale. on the other hand, higgs doublets belong to matter multiplets and hence may have unsuppressed supersymmetry-breaking soft masses. we consider their masses to be equal to the gravitino mass at the high energy scale, assuming the minimal kähler potential for higgs doublets. we show that the fine-tuning measure of the electroweak symmetry-breaking scale is reduced significantly to δ =30{-}70, if the ratio of the gravitino mass to the gaugino mass is around 5/4. also, the prospects for the discovery/exclusion of supersymmetric particles at the large hadron collider and dark matter direct detection experiments are discussed. | seminatural susy from the e7 nonlinear sigma model |
assuming that dark matter (dm) is made of fermions in the sub-gev mass range with interactions dominated by electromagnetic moments of higher order, such as the electric and magnetic dipoles or the anapole moment, we show that direct detection experiments searching for atomic ionisation events in xenon targets can shed light on whether dm is a dirac or majorana particle. specifically, we find that between about 45 (120) and 610 (1700) signal events are required to reject majorana dm in favour of dirac dm with a statistical significance corresponding to 3 (5) standard deviations. the exact number of dm signal events corresponding to a given significance depends on the relative size of the anapole, magnetic dipole and electric dipole contributions to the expected rate of dm-induced atomic ionisations under the dirac hypothesis. our conclusions are based on monte carlo simulations and the likelihood ratio test. while the use of asymptotic formulae for the latter is standard in many applications, here it requires a non-trivial extension to the case where one of the hypotheses lies on the boundary of the parameter space. our results constitute a solid proof of concept about the possibility of using direct detection experiments to reject the majorana dm hypothesis when the dm interactions are dominated by higher-order electromagnetic moments. | rejecting the majorana nature of dark matter with electron scattering experiments |
the search for a novel technology able to detect and reconstruct nuclear recoil events in the kev energy range has become more and more important as long as vast regions of high mass wimp-like dark matter candidate have been excluded. gaseous time projection chambers (tpc) with optical readout are very promising candidate combining the complete event information provided by the tpc technique to the high sensitivity and granularity of last generation scientific light sensors. a tpc with an amplification at the anode obtained with gas electron multipliers (gem) was tested at the laboratori nazionali di frascati. photons and neutrons from radioactive sources were employed to induce recoiling nuclei and electrons with kinetic energy in the range [1-100] kev. a he-cf4 (60/40) gas mixture was used at atmospheric pressure and the light produced during the multiplication in the gem channels was acquired by a high position resolution and low noise scientific cmos camera and a photomultiplier. a multi-stage pattern recognition algorithm based on an advanced clustering technique is presented here. a number of cluster shape observables are used to identify nuclear recoils induced by neutrons originated from a ambe source against x-ray 55fe photo-electrons. an efficiency of 18% to detect nuclear recoils with an energy of about 6 kev is reached obtaining at the same time a 96% 55fe photo-electrons suppression. this makes this optically readout gas tpc a very promising candidate for future investigations of ultra-rare events as directional direct dark matter searches. | identification of low energy nuclear recoils in a gas tpc with optical readout |
we investigate the effect of a first-order electroweak phase transition (foewpt), which is one of the prerequisites for electroweak baryogenesis, on the thermal relic abundance of the dark matter (dm) that freezes out before the phase transition occurs in the complex singlet scalar extended $z_3$-invariant type-ii seesaw model that can simultaneously provide a dm candidate, explain the non-vanishing neutrino masses and the baryon asymmetry of the universe. such a phase transition around the electroweak scale leaves an impact on the relic density due to the release of entropy, particularly for a tev-scale dm. we thus concentrate on the region of parameter space of the said model which favors an foewpt in the early universe and for which the dm is heavy such that its freeze-out temperature turns out to be larger than the phase transition temperature. we further study the dependencies of the dilution factor of the dm relic density on the model parameters, the nucleation temperature, the strength and the duration of the phase transition. such a dilution might retrieve some of the regions of parameter space that were previously ruled out by the measured value of the dm relic density and/or the latest constraints from the dm direct-detection experiments. furthermore, a direct connection is drawn between the dilution factor and the generation of stochastic gravitational waves as a result of an foewpt. | dilution of dark matter relic abundance due to first order electroweak phase transition in the singlet scalar extended type-ii seesaw model |
this paper reports the design and experimental results from the characterization of an integrated circuit developed for the readout of the x-ray spectrometer and tracking system of the general antiparticle spectrometer (gaps) balloon mission. gaps will search for an indirect signature of dark matter through the detection of low-energy (<0.25 gev/n) cosmic-ray antiprotons, antideuterons and antihelium nuclei. the asic, named slider32 (32 channels si-li detector readout asic), was fabricated in a 180 nm cmos technology and is comprised of 32 analog readout channels, an 11-bit sar adc and a digital back-end section which is responsible for defining channel settings and for sending digital information to the data acquisition system. the core of the asic is a low-noise analog channel implementing a dynamic signal compression which makes the chip suitable for resolving both x-rays in the range of 20 to 100 kev and charged particles with energy deposition of up to 100 mev. it features an energy resolution of 4 kev fwhm in the 20-100 kev range with a 40 pf detector capacitance, to clearly distinguish x-rays from antiprotonic or antideuteronic exotic atoms. the readout electronics of the asic will run at a temperature of about -40 ° c , complying with a detector leakage current of the order of 5-10 na per strip. | a mixed-signal processor for x-ray spectrometry and tracking in the gaps experiment |
the comparison of the results of direct detection of dark matter, obtained with various target nuclei, requires model-dependent, or even arbitrary, assumptions. indeed, to draw conclusions either the spin-dependent (sd) or the spin-independent (si) interaction has to be neglected. in the light of the null results from supersymmetry searches at the lhc, the squark sector is pushed to high masses. we show that for a squark sector at the tev scale, the framework used to extract constraints from direct detection searches can be redefined as the number of free parameters is reduced. moreover, the correlation observed between si and sd proton cross sections constitutes a key issue for the development of the next generation of dark matter detectors. | extracting constraints from direct detection searches of supersymmetric dark matter in the light of null results from the lhc in the squark sector |
we study the effect of gravitational focusing of the earth on dark matter. we find that the effect can produce a detectable diurnal modulation in the dark matter signal for part of the parameter space which for high dark matter masses is larger than the diurnal modulation induced by the fluctuations in the flux of dark matter particles due to the rotation of the earth around its own axis. the two sources of diurnal modulation have different phases and can be distinguished from each other. we demonstrate that the diurnal modulation can potentially check the self-consistency of experiments that observe annual modulated signals that can be attributed to dark matter. failing to discover a daily varying signal can result conclusively in the falsification of the hypothesis that the annual modulation is due to dark matter. we also suggest that null result experiments should check for a daily modulation of their rejected background signal with specific phases. a potential discovery could mean that dark matter collisions have been vetoed out. | daily modulation and gravitational focusing in direct dark matter search experiments |
newsdm [nuclear emulsions for wimp (weakly interacting massive particles) search—directional measurement] is a new international experiment in which a photoemulsion target is used for a direct detection of dark-matter particles. in this experiment, the detection method is based on fixing the directions of trajectories of recoil nuclei originating from the elastic interaction of target nuclei with dark-matter particles from the galactic halo. this distinguishes newsdm from standard low-background experiments aimed at searches for dark-matter particles and based on an analysis of annual modulations of the number of detected events. the detector, which is simultaneously a target, is a block of nuclear emulsions that have a uniquely high spatial resolution owing to the reduction of the size of agbr grains to about nm. a resolution on this order of magnitude permits directional searches for dark-matter particles in cosmic space even at energies of recoil nuclei not higher than 30 kev. | new experiment newsdm for direct searches for heavy dark matter particles |
we study the properties and direct detection prospects of an as of yet neglected population of dark matter (dm) particles moving in orbits gravitationally bound to the earth. this dm population is expected to form via scattering by nuclei in the earth's interior. we compute fluxes and nuclear recoil energy spectra expected at direct detection experiments for the new dm population considering detectors with and without directional sensitivity, and different types of target materials and dm-nucleon interactions. dm particles bound to the earth manifest as a prominent rise in the low-energy part of the observed nuclear recoil energy spectrum. ultra-low threshold energies of about 1 ev are needed to resolve this effect. its shape is independent of the dm-nucleus scattering cross-section normalization. | direct detection of dark matter bound to the earth |
several searches for dark matter have been performed by the cms and atlas collaborations, using proton-proton collisions with a center-of-mass energy of 13 tev produced by the large hadron collider. different signatures may highlight the presence of dark matter: the imbalance in the transverse momentum in an event due to the presence of undetectable dark matter particles, produced together with one standard model particle, a bump in the di-jet or di-lepton invariant mass distributions, or an excess of events in the di-jet angular distribution, produced by a dark matter mediator. no significant discrepancies with respect to the standard model predictions have been found in data, so that limits on the dark matter couplings to ordinary matter, or limits on the dark matter particles and mediators masses have been set. the results are also re-interpreted as limits on the dark matter interaction cross-section with baryonic matter, so that a comparison with direct detection experiments is allowed. | collider searches for dark matter (atlas + cms) |
we show that models of strongly interacting (simp) dark matter built to reproduce the dama signal actually cannot account for its time dependence. we discuss the constraints on this type of models coming from direct detection experiments and study the propagation of thermalised dark matter particles in the ground for the allowed values of the parameters. we consider a simple 1d diffusion and a more detailed 3d diffusion. in both cases the predicted signal has either the wrong phase of the annual modulation or a much larger amplitude of the diurnal modulation. | strongly interacting dark matter and the dama signal |
scintillator doped with a high neutron-capture cross-section material can be used to detect neutrons via their resulting gamma rays. examples of such detectors using liquid scintillator have been successfully used in high-energy physics experiments. however, a liquid scintillator can leak and is not as amenable to modular or complex shapes as a solid scintillator. polystyrene-based scintillators from a variety of gadolinium compounds with varying concentrations were polymerized in our laboratory. the light output, emission spectra, and attenuation length of our samples were measured and light collection strategies using a wavelength shifting (wls) fiber were evaluated. the measured optical parameters were used to tune a geant4-based optical monte carlo, enabling the trapping efficiency to be calculated. this technology was also evaluated as a possible neutron veto for the direct detection dark matter experiment, super cryogenic dark matter search (supercdms). | characterization of gadolinium-loaded plastic scintillator for use as a neutron veto |
we show how the material used in direct detection experiments of dark matter (dm), in the presence of a signal of it, can afford one with the possibility of extracting the nature of the underlying candidate. we do so for the case of a u(1) ' supersymmetric standard model (ussm) of e6 origin, by exploiting benchmark points over its parameter space that yield either a singlino- or higgsino-like neutralino as dm candidate, the latter being defined in presence of up-to-date constraints, from low to high energy and from collider to non-collider experiments. however, as our method is general, we also introduce a model-independent description of our analysis, for the purpose of aiding similar studies in other beyond the standard model (bsm) scenarios. this has been made possible by adapting a rather simple χ2 analysis normally used for signal extraction in direct detection experiments and the procedure has been applied to xenon, germanium and silicon detectors, those showing maximal and complementary sensitivity to gauge- and higgs-portal induced interactions of dm with their nuclei. | characterisation of dark matter in direct detection experiments: singlino versus higgsino |
we present a detailed analysis of the effect of an observationally determined dark matter (dm) velocity distribution function (vdf) of the milky way (mw) on dm direct detection rates. we go beyond local kinematic tracers and use rotation curve data up to 200 kpc to construct a mw mass model and self-consistently determine the local phase-space distribution of dm. this approach mitigates any incomplete understanding of local dark matter-visible matter degeneracies that can affect the determination of the vdf. comparing with the oft used standard halo model (shm), which assumes an isothermal vdf, we look at how the tail of the empirically determined vdf alters our interpretation of the present direct detection wimp dm cross section exclusion limits. while previous studies have suggested a very large difference (of more than an order of magnitude) in the bounds at low dm masses, we show that accounting for the detector response at low threshold energies, the difference is still significant although less extreme. the change in the number of signal events, when using the empirically determined dm vdf in contrast to the shm vdf, is most prominent for low dm masses for which the shape of the recoil energy spectrum depends sensitively on the detector threshold energy as well as detector response near the threshold. we demonstrate that these trends carry over to the respective dm exclusion limits, modulo detailed understanding of the experimental backgrounds. with the unprecedented precision of astrometric data in the gaia era, use of observationally determined dm phase space will become a critical and necessary ingredient for dm searches. we provide an accurate fit to the current best observationally determined dm vdf (and self-consistent local dm density) for use in analyzing current dm direct detection data by the experimental community. | observationally inferred dark matter phase-space distribution and direct detection experiments |
in the present work, we study the atomic compton scattering that could have a great impact on dark matter direct detection experiments. we give a quantitative analysis of the compton scattering energy spectrum for si and ge atomic systems. the theoretical results on compton scattering are calculated within the frameworks of free electron approximation (fea) and relativistic impulse approximation (ria). the low-energy transfer and near photoionization threshold regions are especially considered in this work. in ria calculations, to obtain the atomic ground states, we adopt an ab initio calculation in the fully relativistic dirac-fock theory. | compton scattering energy spectrum for si and ge systems |
pseudo nambu-goldstone bosons (pngbs) are attractive dark matter (dm) candidates, since they couple to the standard model (sm) predominantly through derivative interactions. thereby they naturally evade the strong existing limits inferred from dm direct detection experiments. working in an effective field theory that includes both derivative and non-derivative dm-sm operators, we perform a detailed phenomenological study of the large hadron collider reach for pngb dm production in association with top quarks. drawing on motivated benchmark scenarios as examples, we compare our results to other collider limits as well as the constraints imposed by dm (in)direct detection experiments and the relic abundance. we furthermore explore implications on the viable parameter space of pngb dm. in particular, we demonstrate that dm direct detection experiments become sensitive to many pngb dm realisations once loop-induced interactions are taken into account. the search strategies and pngb dm benchmark models that we discuss can serve as a starting point for dedicated experimental analyses by the atlas and the cms collaborations. | searching for pseudo nambu-goldstone boson dark matter production in association with top quarks |
updating a previous analysis where we used elastic nuclear recoils we study the migdal effect to extend to low wimp masses the direct detection bounds to operators up to dimension 7 of the relativistic effective field theory describing wimp interactions with quarks and gluons. to this aim we include in our analysis the data of the xenon1t, supercdms, cosine-100, and darkside-50 experiments and assume a standard maxwellian for the wimp velocity distribution. we find that the bounds can reach down to a wimp mass ≃20 mev, although in the case of higher-dimension operators the energy scale of the ensuing constraints may be inconsistent with the validity of the effective theory. | low-mass extension of direct detection bounds on wimp-quark and wimp-gluon effective interactions using the migdal effect |
we present the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the xenon100 science run ii. this very distinct signature is predicted in the framework of magnetic inelastic dark matter which has been proposed to reconcile the modulation signal reported by the dama/libra collaboration with the null results from other direct detection experiments. no candidate event has been found in the region of interest and upper limits on the wimp's magnetic dipole moment are derived. the scenarios proposed to explain the dama/libra modulation signal by magnetic inelastic dark matter interactions of wimps with masses of 58.0 gev/c2 and 122.7 gev/c2 are excluded at 3.3 σ and 9.3 σ, respectively. | search for magnetic inelastic dark matter with xenon100 |
in this work we show how the inclusion of dark matter (dm) direct detection upper bounds in a theoretically consistent manner can affect the allowed parameter space of a dm model. traditionally, the limits from dm direct detection experiments on the elastic scattering cross section of dm particles as a function of their mass are extracted under simplifying assumptions. relaxing the assumptions related to the dm particle nature, such as the neutron to proton ratio of the interactions, or the possibility of having similar contributions from the spin independent (si) and spin dependent (sd) interactions can vary significantly the upper limits. furthermore, it is known that astrophysical and nuclear uncertainties can also affect the upper bounds. to exemplify the impact of properly including all these factors, we have analysed two well motivated and popular dm scenarios: neutralinos in the nmssm and a z' portal with dirac dm. we have found that the allowed parameter space of these models is subject to important variations when one includes both the si and sd interactions at the same time, realistic neutron to proton ratios, as well as using different self-consistent speed distributions corresponding to popular dm halo density profiles, and distinct sd structure functions. finally, we provide all the necessary information to include the upper bounds of supercdms and lux taking into account all these subtleties in the investigation of any particle physics model. the data for each experiment and example codes are available at this site http://goo.gl/1cdfyi, and their use is detailed in the appendices of this work. | on the importance of direct detection combined limits for spin independent and spin dependent dark matter interactions |
the darkside experiment is designed for the direct detection of dark matter with a double phase liquid argon tpc operating underground at laboratori nazionali del gran sasso. the tpc is placed inside a 30 tons liquid organic scintillator sphere, acting as a neutron veto, which is in turn installed inside a 1 kt water cherenkov detector. the current detector is running since november 2013 with a 50 kg atmospheric argon fill and we report here the first null results of a dark matter search for a (1422 ± 67) kg.d exposure. this result correspond to a 90% cl upper limit on the wimp-nucleon cross section of 6.1 × 10-44 cm2 (for a wimp mass of 100 gev/c2) and it's currently the most sensitive limit obtained with an argon target. | direct search for dark matter with darkside |
assuming that dark matter (dm) efficiently clusters on various scales we analyse the possible impact on direct dm searches. for certain sizes and densities of dm clusters, mutual detector-cluster encounters may occur only once a year or every several years leading to the apparent failure of individual experiments searching for dm to discover it. if, however, encounters with earth size and up to $10^4$ times bigger clusters occur about once a year, then finding time correlations between events in different underground detectors can lead to dm discovery. | dark matter clusters and time correlations in direct detection experiments |
we consider the special case that the dark matter (dm) candidate is not detected in direct-detection programs when the experimental sensitivity reaches the neutrino flux background. in such circumstance the dm searches at the colliders impose constraints on the dm relic abundance if the dm candidate is a wimps type. specifically, we consider the triplet (quintet and septet) dms in the framework of minimal dm model and explore the potential of discovering the dm candidate in the mono-jet, mono-photon and vector boson fusion channels at the large hadron collider (lhc) and future 100 tev hadron collider. if the dm candidate in such a scenario is discovered at the lhc, then additional dm candidates are needed to explain the observed relic abundance. on the other hand, null results in those dm searching programs at the colliders give rise to lower limits of dm relic abundance. | measuring relic abundance of minimal dark matter at hadron colliders |
we study the phenomenology of a model that addresses the neutrino mass, dark matter, and generation of the electroweak scale in a single framework. electroweak symmetry breaking is realized via the coleman-weinberg mechanism in a classically scale invariant theory, while the neutrino mass is generated radiatively through interactions with dark matter in a typically scotogenic manner. the model introduces a scalar triplet and singlet and a vector-like fermion doublet that carry an odd parity ofz_2 , and an even parity scalar singlet that helps preserve classical scale invariance. we sample over the parameter space by taking into account various experimental constraints from the dark matter relic density and direct detection, direct scalar searches, neutrino mass, and charged lepton flavor violating decays. we then examine by detailed simulations possible signatures at the lhc to find some benchmark points of the free parameters. we find that the future high-luminosity lhc will have a significant potential in detecting new physics signals in the dilepton channel. | dark matter and lhc phenomenology of a scale-invariant scotogenic model |
a light scalar field framework of dark energy, sometimes referred to as quintessence, introduces a fifth force between normal matter objects. screening mechanisms, such as the chameleon model, allow the scalar field to be almost massless on cosmological scales while simultaneously evading laboratory constraints. we explore the ability of existing mechanical systems to directly detect the fifth force associated with chameleons in an astrophysically viable regime where it could be dark energy. we provide analytical expressions for the weakest accessible chameleon model parameters in terms of experimentally tunable variables and apply our analysis to two mechanical systems: levitated microspheres and torsion balances, showing that the current generation of these experiments have the sensitivity to rule out a significant portion of the proposed chameleon parameter space. we also indicate regions of theoretically well-motivated chameleon parameter space to guide future experimental work. | searching for chameleon dark energy with mechanical systems |
it has recently been demonstrated that, in the event of a putative signal in dark matter direct detection experiments, properly identifying the underlying dark matter-nuclei interaction promises to be a challenging task. given the most optimistic expectations for the number counts of recoil events in the forthcoming generation 2 experiments, differentiating between interactions that produce distinct features in the recoil energy spectra will only be possible if a strong signal is observed simultaneously on a variety of complementary targets. however, there is a wide range of viable theories that give rise to virtually identical energy spectra, and may only differ by the dependence of the recoil rate on the dark matter velocity. in this work, we investigate how degeneracy between such competing models may be broken by analyzing the time dependence of nuclear recoils, i.e. the annual modulation of the rate. for this purpose, we simulate dark matter events for a variety of interactions and experiments, and perform a bayesian model-selection analysis on all simulated data sets, evaluating the chance of correctly identifying the input model for a given experimental setup. we find that including information on the annual modulation of the rate may significantly enhance the ability of a single target to distinguish dark matter models with nearly degenerate recoil spectra, but only with exposures beyond the expectations of generation 2 experiments. | prospects for distinguishing dark matter models using annual modulation |
we examine the impact of the expected reach of the lhc and the xenon1t experiments on the parameter space of the minimal classically scale invariant extension of the standard model (sm), where all the mass scales are induced dynamically by means of the coleman-weinberg mechanism. in this framework, the sm content is enlarged by the addition of one complex gauge-singlet scalar with a scale invariant and c p -symmetric potential. the massive pseudoscalar component, protected by the c p symmetry, forms a viable dark matter candidate, and three flavors of the right-handed majorana neutrinos are included to account for the nonzero masses of the sm neutrinos via the seesaw mechanism. the projected constraints on the parameter space arise by applying the atlas heavy higgs discovery prospects, with an integrated luminosity of 300 and 3000 fb-1 at √{s }=14 tev , to the pseudo-nambu-goldstone boson of the (approximate) scale symmetry, as well as by utilizing the expected reach of the xenon1t direct detection experiment for the discovery of the pseudoscalar dark matter candidate. a null-signal discovery by these future experiments implies that vast regions of the model's parameter space can be thoroughly explored; the combined projections are expected to confine a mixing between the sm and the singlet sector to very small values while probing the viability of the tev scale pseudoscalar's thermal relic abundance as the dominant dark matter component in the universe. furthermore, the vacuum stability and triviality requirements of the framework up to the planck scale are studied, and the viable region of the parameter space is identified. the results are summarized in extensive exclusion plots, incorporating additionally the prior theoretical and experimental bounds for comparison. | prospects for discovering the higgs-like pseudo-nambu-goldstone boson of the classical scale symmetry |
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 explore the sparticle spectroscopy of the supersymmetric su(5) model with non-universal gaugino masses in light of latest experimental searches. we assume that the gaugino mass parameters are independent at the gut scale. we find that the observed deviation in the anomalous magnetic moment of the muon can be explained in this model. the parameter space that explains this deviation predicts a heavy colored sparticle spectrum whereas the sleptons can be light. we also find a notable region of the parameter space that yields the desired relic abundance for dark matter. in addition, we analyze the model in light of latest limits from direct detection experiments and find that the parameter space corresponding to the observed deviation in the muon anomalous magnetic moment can be probed at some of the future direct detection experiments. | su(5) with non-universal gaugino masses |
we describe the electronics and data acquisition system used in the first phase of the pandax experiment—a 120 kg dual-phase liquid xenon dark matter direct detection experiment in the china jin-ping underground laboratory. this system utilized 180 channels of commercial flash adc waveform digitizers. during the entire experimental run, the system has achieved low trigger threshold (<1 kev electron-equivalent energy) and low deadtime data acquisition. | the electronics and data acquisition system for the pandax-i dark matter experiment |
we present a calculation of the next-to-leading order qcd corrections for the scattering of dark matter particles off nucleons in the framework of simplified models with s- and t-channel mediators. these results are matched to the wilson coefficients and operators of an effective field theory that is generally used for the presentation of experimental results on spin-independent and spin-dependent direct detection rates. detailed phenomenological studies illustrate the complementary reach of collider searches for dark matter and the direct detection experiments cresst and xenon. in the case of cancellation effects in the tree-level contributions, one-loop corrections can have a particularly large impact on exclusion limits in the case of combined s +t -channel models. | direct detection of dark matter: precision predictions in a simplified model framework |
the quantum size effect (qse) studies of metallic and semiconductor nanoparticles have received considerable attention for their applications in superconductivity, visible light emission, quantum dot devices and industrial catalysts. the qse properties of semiconductor agbr nanoparticles have been thoroughly characterized for cluster larger than three nanometers in diameter, the qse studies of clusters in the quantum size regime less than 3nm have been historically difficult to describe owing to weak optical absorption and challenge in keep cluster in small size range against self aggregation. such difficulties have precluded probing the properties of these small clusters in many natural and engineered processes. our previous investigation of silver bromide ionic clusters that prepared via the electroporation of vesicles using direct laser desorption -- time of flight -- mass spectrometry (dld-tof-ms) had successfully revealed relation ship between cluster structure and the uv absorption band shift. the turn-around point had been experimentally identified to be $ (ag_3br_2)^+ $, which is close to the theoretical prediction. despite those successes, there a lot of questions not be answered. these unanswered questions include why dld-tof-ms spectra show an unsymmetrical cluster finger peaks? why the large clusters have much lower dld-tof-ms spectra intensity? why the cluster uv absorption have such wide band and it takes so long time to observe the band shift? in this paper, we reexamine our previous theoretical work and systematically answer the above questions with symmetry and probability principles in molecular cluster growth range. we also discussed the isotopic properties of silver bromide clusters and their possible applications on the dark matter detection based on recent findings that isotopic atoms can decay while interact with dark matters. | studies of silver bromide clusters isotopic properties and their applications |
dark matter axions, particles whose hypothesized existence could resolve two of the largest outstanding mysteries in physics, are made difficult to detect by their extremely feeble coupling to ordinary matter. the axion haloscope, first realized experimentally three decades ago, remains among the most viable detection platforms, but even today's leading technology would optimistically require many millennia to scan commonly targeted portions of axion parameter space. today's axion direct detection community is searching therefore not just for the elusive particles, but for technologies and innovations that will permit more efficient searches. in this thesis, i present two such innovations. first, the resource of quantum squeezing sequesters the noise of a haloscope measurement into unmeasured observables, improving the sensitivity bandwidth and hence the scan rate of the detector, its primary figure of merit. second, valuable information pertinent to the existence of the axion is discarded by the standard hypothesis testing framework used to look for axions. an alternative, bayesian analysis utilizes the full information content of the haloscope measurement, yielding a tangible speedup at zero operational or hardware cost. together, these innovations are used improve threefold the scan rate of a dark matter search performed by the haloscope at yale sensitive to axion cold dark matter (haystac) experiment. | enhancing the scan rate for axion dark matter: quantum noise evasion and maximally informative analysis |
chiral effective field theory allows one to calculate the response of few-nucleon systems to external currents, both for currents that can be probed in the standard model and ones that only exist in standard-model extensions. in combination with state-of-the-art many-body methods, the constraints from chiral symmetry can then be implemented in nuclear structure factors that describe the response of atomic nuclei in direct-detection searches for dark matter. we review the present status of this approach, including the role of coherently enhanced two-body currents, the discrimination of dark matter candidates based on the nuclear response functions, and limits on higgs-portal dark matter. | dark-matter-nucleus scattering in chiral effective field theory |
we investigate an electroweak interacting dark matter (dm) model in which the dm is the neutral component of the su(2)l triplet fermion that couples to the standard model (sm) higgs sector via an sm singlet higgs boson. in this setup, the dm can have a cp-violating coupling to the singlet higgs boson at the renormalizable level. as long as the nonzero higgs portal coupling (singlet-doublet higgs boson mixing) exists, we can probe cp violation of the dm via the electric dipole moment of the electron. assuming the o (1) cp-violating phase in magnitude, we investigate the relationship between the electron edm and the singlet-like higgs boson mass and coupling. it is found that for moderate values of the higgs portal couplings, current experimental edm bound is not able to exclude the wide parameter space due to a cancellation mechanism at work. we also study the spin-independent cross section of the dm in this model. it is found that although a similar cancellation mechanism may diminish the leading-order correction, as often occurs in the ordinary higgs portal dm scenarios, the residual higher-order effects leave an o (10-47) cm2 correction in the cancellation region. it is shown that our benchmark scenarios would be fully tested by combining all future experiments of the electron edm, dm direct detection and higgs physics. | electroweak interacting dark matter with a singlet scalar portal |
we consider a minimal natural supersymmetric model based on an extra dimension with supersymmetry breaking provided by the scherk-schwarz mechanism. the lightest supersymmetric particle is a neutral, quasi-dirac higgsino and, unlike in previous studies, we assume that all standard model fields are propagating in the bulk. the resulting setup is minimal, as neither extra matter, effective operators, nor extra u (1 ) groups are needed in order to be viable. the model has three free parameters which are fixed by the higgsino mass—set to the range 1.1-1.2 tev so it can play the role of dark matter, and by the requirements of correct electroweak breaking and the mass of the higgs. after imposing the previous conditions we find a benchmark scenario that passes all experimental constraints with an allowed range for the supersymmetric parameters. in particular we have found gluinos in the range 2.0-2.1 tev mass, electroweakinos and sleptons almost degenerate in the range 1.7-1.9 tev and squarks degenerate in the range 1.9-2.0 tev. the best discovery prospects are: (i) gluino detection at the high luminosity lhc (≳3 ab-1 ), and (ii) higgsino detection at next-generation dark matter direct detection experiments. the model is natural, as the fine-tuning for the fixed values of the parameters is moderate mainly because supersymmetry breaking parameters contribute linearly to the higgs mass parameter, rather than quadratically as in most models. | higgsino dark matter in an economical scherk-schwarz setup |
we show that compatibility between the dama modulation result (as well as less statistically significant excesses such as the cdms silicon effect and the excess claimed by cresst) with constraints from other experiments can be achieved by extending the analysis of direct detection data beyond the standard elastic scattering of a wimp off nuclei with a spin--dependent or a spin--independent cross section and with a velocity distribution as predicted by the isothermal sphere model. to do so we discuss several new approaches for the analysis of dark matter direct detection data, with the goal to remove or reduce its dependence on specific theoretical assumptions, and to extend its scope: the factorization approach of astrophysics uncertainties, the classification and study of wimp-nucleon interactions within non--relativistic field theory, inelastic scattering and isovector-coupling cancellations including subdominant two-nucleon nlo effects. typically, combining two or more of these ingredients can lead to conclusions which are very different to what usually claimed in the literature. this shows that we are only starting now to scratch the surface of the most general wimp direct detection parameter space. | new approaches in the analysis of dark matter direct detection data: scratching below the surface of the most general wimp parameter space |
studying the structure of nucleons is not only important to understanding the strong interactions of quarks and gluons, but also to improving the precision of new-physics searches. since a broad class of experiments, including the lhc and dark-matter detection, require standard-model backgrounds with parton distribution functions (pdfs) as inputs for disentangling sm contributions from potential new physics. for a long time, lattice calculations of the pdfs (as well as many hadron structures) has been limited to the first few moments. in this talk, we present a first direct calculation of the bjorken-x dependence of the pdfs using large-momentum effective theory (lamet). an exploratory study of the antiquark/sea flavor asymmetry of these distributions will be discussed. this breakthrough opens an exciting new frontier calculating more complicated quantities, such as gluon structure and transverse-momentum dependence, which will complement existing theoretical programs for the upcoming electron-ion collider (eic) or large hadron-electron collider (lhec). | from c to parton sea: bjorken-x dependence of the pdfs |
using the existing simplified model framework, we build several dark matter models which have suppressed spin-independent scattering cross section. we show that the scattering cross section can vanish due to interference effects with models obtained by simple combinations of simplified models. for weakly interacting massive particle (wimp) masses ≳10 gev, collider limits are usually much weaker than the direct detection limits coming from lux or xenon100. however, for our model combinations, lhc analyses are more competitive for some parts of the parameter space. the regions with direct detection blind spots can be strongly constrained from the complementary use of several large hadron collider (lhc) searches like mono-jet, jets + missing transverse energy, heavy vector resonance searches, etc. we evaluate the strongest limits for combinations of scalar + vector, "squark" + vector, and scalar + "squark" mediator, and present the lhc 14 tev projections. | blind spots for direct detection with simplified dm models and the lhc |
we report a systematic study on the directional sensitivity of a direct dark matter detector that detects the polar angle of a recoiling nucleus. a weakly interacting massive particle (wimp)-mass independent method is used to obtain the sensitivity of a general detector in an isothermal galactic dark matter halo. by using two-dimensional distributions of energy and polar angle, a detector without head-tail information with 6.3 times the statistics is found to achieve the same performance level as a full three-dimensional tracking dark matter detector. optimum operation orientations are obtained for various experimental configurations, with detectors that are space- or earth-fixed, have head-tail capability or not, and use energy information or not. earth-fixed detectors are found to have best sensitivity when the polar axis is oriented at a 45 degree angle from the earth's pole. with background contamination that mimics the wimp signal's energy distribution, the performance is found to decrease at a rate less than the decrease of signal purity. the wimp-mass dependence of the performance of a detector with various energy thresholds that uses gaseous xenon as target material is reported. we find that with a 5 ×10-46 cm2 spin-independent wimp-nucleon cross-section and a 30 gev wimp, a 770 kg .year 's exposure with a polar detector of 10 kev threshold can make a three sigma discovery of directional wimps in the isothermal galactic dark matter halo. for a columnar recombination detector, experimental considerations are discussed. | directional dark matter by polar angle direct detection and application of columnar recombination |
the sensitivity of the direct detection of dark matter (dm) approaches the so-called neutrino floor, below which it is difficult to disentangle the dm candidate from the neutrino background. in this work, we consider the scenario that no dm signals are reported in various dm direct detection experiments and explore whether collider searches could probe dm below the neutrino floor. we adopt several simplified models in which the dm candidate couples to electroweak gauge bosons or leptons in the standard model only through high-dimensional operators. after including the rge running effect, we investigate the constraints of direct detection, indirect detection, and collider searches. the collider search can probe light dm below the neutrino floor. particularly, for the effective interaction of $ \bar{\chi}\chi b_{\mu\nu}b^{\mu\nu}$ , current data from the mono-photon channel at the 13 tev lhc has already covered the entire parameter space of the neutrino floor. * supported in part by the national science foundation of china (11725520, 11675002, 11635001) and in part by the china postdoctoral science foundation (8206300015) | dark matter search at colliders and neutrino floor |
models of nuclear dark matter propose that the dark sector contains large composite states consisting of dark nucleons in analogy to standard model nuclei. we examine the direct detection phenomenology of a particular class of nuclear dark matter model at the current generation of tonne-scale liquid noble experiments, in particular deap-3600 and xenon1t. in our chosen nuclear dark matter scenario distinctive features arise in the recoil energy spectra due to the non-point-like nature of the composite dark matter state. we calculate the number of events required to distinguish these spectra from those of a standard point-like wimp state with a decaying exponential recoil spectrum. in the most favourable regions of nuclear dark matter parameter space, we find that a few tens of events are needed to distinguish nuclear dark matter from wimps at the 3 σ level in a single experiment. given the total exposure time of deap-3600 and xenon1t we find that at best a 2 σ distinction is possible by these experiments individually, while 3 σ sensitivity is reached for a range of parameters by the combination of the two experiments. we show that future upgrades of these experiments have potential to distinguish a large range of nuclear dark matter models from that of a wimp at greater than 3 σ. | can tonne-scale direct detection experiments discover nuclear dark matter? |
we examine the question to what extent prospective detection of dark matter by direct and indirect- detection experiments could shed light on what fraction of dark matter was generated thermally via the freeze-out process in the early universe. by simulating putative signals that could be seen in the near future and using them to reconstruct wimp dark matter properties, we show that, in a model- independent approach this could only be achieved in a thin sliver of the parameter space. however, with additional theoretical input the hypothesis about the thermal freeze-out as the dominant mechanism for generating dark matter can potentially be verified. we illustrate this with two examples: an effective field theory of dark matter with a vector messenger and a higgsino or wino dark matter within the mssm. | towards understanding thermal history of the universe through direct and indirect detection of dark matter |
direct detection experiments are still one of the most promising ways to unravel the nature of dark matter. to fully understand how well these experiments constrain the dark matter interactions with the standard model particles, all the uncertainties affecting the calculations must be known. it is especially critical now because direct detection experiments recently moved from placing limits only on the two elementary spin independent and spin dependent operators to the complete set of possible operators coupling dark matter and nuclei in nonrelativistic theory. in our work, we estimate the effect of nuclear configuration-interaction uncertainties on the exclusion bounds for one of the existing xenon-based experiments for all fifteen operators. we find that for operator number 13 the ±1 σ uncertainty on the coupling between the dark matter and nucleon can reach more than 50% for dark matter masses between 10 and 1000 gev. in addition, we discuss how quantum computers can help to reduce this uncertainty and how the uncertainties are affected for couplings obtained for the nonrelativistic reductions of the relativistic interactions. | uncertainties on the eft coupling limits for direct dark matter detection experiments stemming from uncertainties of target properties |
some theoretical and experimental aspects regarding the direct dark matter field are mentioned. in particular some arguments, which play a relevant role in the evaluation of model-dependent interpretations of experimental results and in comparisons, are shortly addressed. | on corollary model-dependent analyses and comparisons |
dark matter particles may bind with nuclei if there exists an attractive force of sufficient strength. we show that a dark photon mediator of mass ∼(10 -100 ) mev that kinetically mixes with standard model electromagnetism at the level of ∼10-3 generates kev-scale binding energies between dark matter and heavy elements, while forbidding the ability to bind with light elements. in underground direct detection experiments, the formation of such bound states liberates kev-scale energy in the form of electrons and photons, giving rise to monoenergetic electronic signals with a time structure that may contain daily and seasonal modulations. we show that data from liquid-xenon detectors provides exquisite sensitivity to this scenario, constraining the galactic abundance of such dark particles to be at most ∼10-18-10-12 of the galactic dark-matter density for masses spanning ∼(1 -105) gev . however, an exponentially small fractional abundance of these dark particles is enough to explain the observed electron recoil excess at xenon1t. | low-energy signals from the formation of dark-matter-nucleus bound states |
we study the self conjugate dark matter (dm) particles interacting primarily with the standard model leptons in an effective field theoretical frame work. we consider sm gauge invariant effective contact interactions between the majorana fermion, real scalar and a real vector dm with leptons by evaluating the wilson coefficients appropriate for interaction terms upto dimension-8 and obtain constraints on the parameters of the theory from the observed relic density, indirect detection observations and from the dm-electron scattering cross-sections in the direct detection experiments. low energy lep data has been used to study sensitivity in the pair production of such low mass $\le$ 80 gev dm particles. pair production of dm particles of mass $\ge$ 50 gev in association with mono-photons at the proposed ilc has rich potential to probe such effective operators. | effective field theory approach to lepto-philic self conjugate dark matter |
no dark matter particles have been observed by two of the world's most sensitive direct-detection experiments, casting doubt on a favored dark matter model. | dark matter still at large |
the study of dark matter, in both astrophysics and particle physics, has emerged as one of the most active and exciting topics of research in recent years. this book reviews the history behind the discovery of missing mass (or unseen mass) in the universe, and ties this into the proposed extensions to the standard model of particle physics (such as supersymmetry), which were being proposed within the same time frame. this book is written as an introduction to these problems at the forefront of astrophysics and particle physics, with the goal of conveying the physics of dark matter to beginning undergraduate majors in scientific fields. the book goes on to describe existing and upcoming experiments and techniques, which will be used to detect dark matter either directly or indirectly. | dark matter in the universe |
the lux (large underground xenon) experiment aims at the direct detection of dark matter particles via their collisions with xenon nuclei. the 370 kg two-phase liquid xenon time projection chamber measures simultaneously the scintillation and ionization from interactions in the target. the ratio of these two signals provides very good discrimination between potential nuclear recoil and electronic recoil signals to search for wimp-nucleon scattering. the lux detector operates at the sanford underground research facility (lead, south dakota, usa) since february 2013. first results were presented in late 2013 setting the world's most stringent limits on wimp-nucleon scattering cross-sections over a wide range of wimp masses. a 300 day run beginning in 2014 will further improve the sensitivity and new calibration techniques will reduce systematics for the wimp signal search. | results from the lux dark matter experiment |
scintillating calorimeters are cryogenic detectors combining a measurement of scintillation with one of phonons to provide particle identification. in view of developing alkali halide devices of this type able to check the dama/libra claim for the observation of dark matter, we have simulated detector performances to determine their sensitivity by two methods with little model-dependence. we conclude that if performance of the phonon channel can be brought in line with those of other materials, an exposure of 10 kg-days would suffice to check the dama/libra claim in standard astrophysical scenarios. additionally, a fairly modest array of 5 kg with background rejection would be able to directly check the dama/libra modulation result in 2 years. | sensitivity of alkali halide scintillating calorimeters with particle identification to investigate the dama dark matter detection claim |
we propose to accommodate economically the type-ii neutrino seesaw mechanism in (g)nmssm from gmsb and amsb, respectively. the heavy triplets within neutrino seesaw mechanism are identified to be the messengers. therefore, the μ -problem, the neutrino mass generation, lfv as well the soft susy breaking parameters can be economically combined in a non-trivial way. general features of such extensions are discussed. the type-ii neutrino seesaw-specific interactions can give additional yukawa deflection contributions to the soft susy breaking parameters of nmssm, which are indispensable to realize successful ewsb and accommodate the 125 gev higgs. relevant numerical results, including the constraints of dark matter and possible lfv processes li→ljγ etc, are also given. we find that our economical type-ii neutrino seesaw mechanism extension of nmssm from amsb or gmsb can lead to realistic low energy nmssm spectrum, both admitting the 125 gev higgs as the lightest cp-even scalar. the possibility of the 125 gev higgs being the next-to-lightest cp-even scalar in gmsb-type scenario is ruled out by the constraints from ewsb, collider and precision measurements. the possibility of the 125 gev higgs being the next-to-lightest cp-even scalar in amsb-type scenario is ruled out by dark matter direct detection experiments. possible constraints from lfv processes li→ljγ can give an upper bound for the messenger scale. | type-ii neutrino seesaw mechanism extension of nmssm from susy breaking mechanisms |
new-generation direct searches for low mass dark matter feature detection thresholds at energies well below 100 ev, much lower than the energies of commonly used x-ray calibration sources. this requires new calibration sources with sub-kev energies. when searching for nuclear recoil signals, the calibration source should ideally cause monoenergetic nuclear recoils in the relevant energy range. recently, a new calibration method based on the radiative neutron capture on 182w with subsequent deexcitation via single γ -emission leading to a nuclear recoil peak at 112 ev was proposed. the cresst-iii dark matter search operated several cawo4-based detector modules with detection thresholds below 100 ev in the past years. we report the observation of a peak around the expected energy of 112 ev in the data of three different detector modules recorded while irradiated with neutrons from different ambe calibration sources. we compare the properties of the observed peaks with geant-4 simulations and assess the prospects of using this for the energy calibration of cresst-iii detectors. | observation of a low energy nuclear recoil peak in the neutron calibration data of the cresst-iii experiment |
ample evidence has been gathered demonstrating that the majority of the mass in the universe is composed of non-luminous, non-baryonic matter. though the evidence for dark matter is unassailable, its nature and properties remain unknown. a broad effort has been undertaken by the physics community to detect dark-matter particles through direct-detection techniques. for over a decade, the dama/libra experiment has observed a highly significant (9.3sigma) modulation in the scintillation event rate in their highly pure nai(tl) detectors, which they use as the basis of a claim for the discovery of dark-matter particles. however, the dark-matter interpretation of the dama/libra modulation remains unverified. while there have been some recent hints of dark matter in the form of a light weakly-interacting massive particle (wimp) from the cogent and cdms-si experiments, when assuming a wimp dark-matter model, several other experiments, including the lux and xenon noble-liquid experiments, the kims csi(tl) experiment, and several bubble chamber experiments, conflict with dama/libra. however, these experiments use different dark-matter targets and cannot be compared with dama/libra in a model-independent way. the uncertainty surrounding the dark-matter model, astrophysical model, and nuclear-physics effects makes it necessary for a new nai(tl) experiment to directly test the dama/libra result. the sodium-iodide with active background rejection (sabre) experiment seeks to provide a much-needed model-independent test of the dama/libra modulation by developing highly pure crystal detectors with very low radioactivity and deploying them in an active veto detector that can reject key backgrounds in a dark-matter measurement. this work focuses on the efforts put forward by the sabre collaboration in developing low-background, low-threshold crystal detectors, designing and fabricating a liquid-scintillator veto detector, and simulating the predicted background spectrum for a dark-matter measurement. in addition, recent controversy surrounding the value of an important parameter for direct detection---the nuclear quenching factor---prompted sabre to perform a measurement of the quenching factor in sodium. the measurement, its results, and the implications for dama/libra and dark matter are also described. | sabre: a search for dark matter and a test of the dama/libra annual-modulation result using thallium-doped sodium-iodide scintillation detectors |
the sensitivity of rare event physics experiments like neutrino or direct dark matter detection crucially depends on the background level. a significant background contribution originates from the primordial actinides thorium (th) and uranium (u) and the progenies of their decay chains. the applicability of ultra-sensitive accelerator mass spectrometry (ams) for the direct detection of th and u impurities in three copper samples is evaluated. although ams has been proven to reach outstanding sensitivities for long-lived isotopes, this technique has only very rarely been used to detect ultra low concentrations of primordial actinides. here it is utilized for the first time to detect primordial th and u in ultra pure copper serving as shielding material in low level detectors. the lowest concentrations achieved were (1.5 ± 0.6) ·10-11 g/g for th and (8 ± 4) ·10-14 g/g for u which corresponds to (59 ± 24) and (1.0 ± 0.5) μbq/kg, respectively. | ultrasensitive detection method for primordial nuclides in copper with accelerator mass spectrometry |
the xenon1t experiment is the first ton-scale dual-phase (liquid-gas) xenon time projection chamber, currently in operation at the laboratori nazionali del gran sasso in italy. the experiment aims at the dark matter direct detection exploiting a ∼2000 kg mass of liquid xenon as a target for interactions of weakly interacting massive particles (wimps) with xenon nuclei. we report the blinded search results of the first science run, using 34.2 live-days of data acquired between november 2016 and january 2017. the wimp dark matter search is performed inside a ( 1042±12 kg fiducial mass and in the [5,40]kev _{rm{nr}} energy range of interest, in which the electronic recoil background was (1.93 ± 0.25)× 10^{-4} events/(kg × day × kev _{ee} . such a background level is the lowest ever achieved in a dark matter detector. the data analysis is performed with the profile likelihood approach and the observations result to be consistent with the background-only hypothesis, thus leading to exclusion limits on the spin-independent wimp-nucleon interaction cross section for wimp masses between 6 and 104 gev/ c2 . the most stringent limit is obtained for 35 gev/ c2 wimps at 7.7×10^{-47} cm 2 with 90% confidence level (xenon collaboration (aprile e. et al.), phys. res. lett., 119 (2017) 181301), which is the lowest cross section ever probed to date. | first dark matter search results of the xenon1t experiment |
the dama/libra observation of an annual modulation in the detection rate compatible with that expected for dark matter is one of the most puzzling results in the present particle physics scenario. this signal is in strong tension with the negative results of other experiments. however, until recently a direct comparison using the same target material (nai(tl)) was lacking. anais (annual modulation with nai scintillators) is a dark matter direct detection experiment located at the canfranc underground laboratory (lsc, spain). its main goal is to test in a model independent way the dama/libra positive result. anais-112, consisting of 112.5 kg of nai(tl) scintillators, was installed at the lsc in 2017 and since then is taking data smoothly with excellent performances. here we present the results of the annual modulation analysis corresponding to three years of anais data. these results are compatible with the absence of modulation and in tension with dama/libra result. moreover, they support our goal of reaching a 3$σ$ sensitivity to the dama/libra result with about 5 years of data. | dark matter annual modulation with anais-112: three years results |
we explore the sparticle spectroscopy of the supersymmetric su(5) model with nonuniversal gaugino masses in light of latest experimental searches. we assume that the gaugino mass parameters are independent at the gut scale. we find that the observed deviation in the anomalous magnetic moment of the muon can be explained in this model. the parameter space that explains this deviation predicts a heavy colored sparticle spectrum whereas the sleptons can be light. we also find a notable region of the parameter space that yields the desired relic abundance for dark matter. in addition, we analyze the model in light of latest limits from direct detection experiments and find that the parameter space corresponding to the observed deviation in the muon anomalous magnetic moment can be probed at some of the future direct detection experiments. | su(5) with nonuniversal gaugino masses |
in this book, the anomaly mediated supersymmetry breaking (amsb) model is explored by searching for charged winos with their subsequent decays collected with the atlas detector at the large hadron collider (lhc). the author develops a new method, called "re-tracking," to detect charged winos that decay before reaching the semiconductor tracker (sct) detector. because the nominal tracking algorithm at the atlas experiment requires at least seven successive hits in the inner tracking system, the sensitivity to charged winos having a fraction of a nanosecond in the past analysis was therefore limited. however, re-tracking requires a minimum of three pixel hits and provides a fully efficient tracking capability for charged winos traversing the pixel detector, resulting in around about 100 times greater efficiency for charged winos with a lifetime ~0.2 ns longer than that in past searches. signal topology is characterized by a jet with large transverse momentum (pt), large missing transverse energy, and a high-pt disappearing track. there are three types of background tracks: interacting hadron trac ks, charged leptons, and tracks with mismeasured pt. a background estimation based on the monte carlo (mc) simulation suffers from large uncertainties due to poor statistics and has difficulty simulating the properties of background tracks. therefore, a data-driven approach has been developed by the author of the book to estimate the background track-pt spectrum. no significant excess above the background expectation is observed for candidate tracks with large transverse momentum, and constraints on the amsb model are obtained. the author shows that in the amsb model, a charged wino mass below 270 gev is excluded at 95% confidence level, which also directly constrains the mass of wino dark matter. | search for charginos nearly mass-degenerate with the lightest neutralino: based on a disappearing-track signature in pp collisions at √s = 8 tev |
the dmdd package enables simple simulation and bayesian posterior analysis of recoil-event data from dark-matter direct-detection experiments under a wide variety of scattering theories. it enables calculation of the nuclear-recoil rates for a wide range of non-relativistic and relativistic scattering operators, including non-standard momentum-, velocity-, and spin-dependent rates. it also accounts for the correct nuclear response functions for each scattering operator and takes into account the natural abundances of isotopes for a variety of experimental target elements. | dmdd: dark matter direct detection |
sterile neutrinos in the kev mass range may constitute the galactic dark matter. various proposed direct detection and laboratory searches are reviewed. the most promising method in the near future is complete energy-momentum reconstruction of individual beta-decay or k-capture events, using atoms suspended in a magneto-optical trap. a survey of suitable isotopes is presented, together with the measurement precision required in a typical experimental configuration. it is concluded that among the most promising are the k-capture isotopes 131cs, which requires measurement of an x-ray and several auger electrons in addition to the atomic recoil, and 7be which has only a single decay product but needs development work to achieve a trapped source. a number of background effects are discussed. it is concluded that sterile neutrinos with masses down to the 5-10 kev region would be detectable, together with relative couplings down to the level 10-10-10-11 in a 1-2 year running time. | proposed experiments to detect kev range sterile neutrinos using energy-momentum reconstruction of beta decay or k-capture events |
we study a two-component dark matter model consisting of a dirac fermion and a complex scalar charged under new u(1) gauge group in the hidden sector. the dark fermion plays the dominant component of dark matter which explains the measured dm relic density of the universe. it has no direct coupling to ordinary standard model particles, thus evading strong constraints from the direct dm detection experiments. the dark fermion is self-interacting through the light dark gauge boson and it would be possible to address that this model can be a resolution to the small scale structure problem of the universe. the light dark gauge boson, which interacts with the standard model sector, is also stable and composes the subdominant dm component. we investigate the model parameter space allowed by current experimental constraints and phenomenological bounds. we also discuss the sensitivity of future experiments such as ship, dune and ilc, for the obtained allowed parameter space. | phenomenology of a two-component dark matter model |
the naturally occurring radioisotope 32si represents a potentially limiting background in future dark matter direct-detection experiments. we investigate sources of 32si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. we infer that the 32si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon "ore" and the details of the silicon-refinement process. the silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of 32si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. we review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32si. to quantitatively evaluate the 32si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. ultimately, it appears feasible to produce silicon detectors with low levels of 32si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle. | naturally occurring 32si and low-background silicon dark matter detectors |
the presence of dark matter (dm), though well established by indirect evidence, is yet to be observed directly. various dm detection experiments running for several years have yielded no positive results. in view of these negative results, we had earlier proposed alternate models by postulating a minimum gravitational field strength (minimum curvature) and a minimum acceleration. these postulates led to the modified newtonian dynamics and modified newtonian gravity (mong). the observed flat rotation curves of galaxies were also accounted for through these postulates. here, we extend these postulates to galaxy clusters and model the dynamical velocity-distance curve for a typical cluster such as the virgo cluster. the radial velocities of galaxies in the virgo cluster are also obtained through this model. observations show an inconsistency in the hubble flow at a mean cluster distance of 17 mpc, which is expected in regions of high matter density. this decrease in velocity is predicted by our model of modified gravity (mong). the radial velocity versus distance relation for galaxies in the virgo cluster obtained using mong is in agreement with observations. | mong: an extension to galaxy clusters |
the application of very low background techniques has a great importance in deep underground experiments devoted to the investigation of the dark matter (dm) particles and of other rare processes. in this paper, some related arguments are addressed mainly considering their crucial role in case of inorganic crystal scintillators developed for direct dm investigation and, in particular, in the realization of dama/libra apparatus. | adopted low background techniques and analysis of radioactive trace impurities |
radiatively-driven natural supersymmetry, a theoretically and experimentally well-motivated framework, centers around the predicted existence of four light, nearly mass-degenerate higgsinos with mass $\sim 100-200$ gev (not too far above $m_z$). the small mass splittings amongst the higgsinos, typically 4-20 gev, results in very little visible energy arising from decays of the heavier higgsinos. given that other susy particles are considerably heavy, this makes detection challenging at hadron colliders. on the other hand, the clean environment of an electron-positron collider with $\sqrt{s}>2m_{higgsino}$ would enable a decisive search of these required higgsinos, and thus either the discovery or exclusion of natural susy. we present a detailed simulation study of precision measurements of higgsino masses and production cross sections at $\sqrt{s}$ = 500 gev of the proposed international linear collider currently under consideration for construction in japan. the study is based on a geant4 simulation of the international large detector concept. we examine several benchmark points just beyond the hl-lhc reach, with four light higgsinos directly accessible by the ilc, and the mass differences between the lightest susy particle and the heavier states ranging from about 4 to 20 gev. it can be shown that their masses and production cross sections can be precisely measured to approximately 1\% precision or better. these precise measurements allow for extracting the underlying weak scale susy parameters, giving predictions for the masses of heavier susy states. these provide motivation for future high-energy colliders. additionally, dark matter properties may be derived. evolution of the measured gaugino masses to high energies should allow testing the hypothesis of gaugino mass unification. | naturalness and light higgsinos: why ilc is the right machine for susy discovery |
the direct detection of dark matter constituents, in particular the weakly interacting massive particles (wimps), is central to particle physics and cosmology. in this paper we study transitions to the excited states, possible in some nuclei, which have sufficiently low lying excited states. examples considered previously were the first excited states of 127i and 129xe. we examine here 83kr, which offers some kinematical advantages and is a possible target. we estimate appreciable rates for the inelastic scattering mediated by the spin cross sections, with an inelastic event rate of 4.4 ×10-4 kg-1 d-1 . so, the extra signature of the gamma ray following the de-excitation of these states can, in principle, be exploited experimentally. a brief discussion of the experimental feasibility is given. | theoretical direct wimp detection rates for transitions to the first excited state in 83kr |
weak scale supersymmetry (susy) remains a prime explanation for the radiative stability of the higgs field. a natural account of the higgs boson mass, however, strongly favors extensions of the minimal supersymmetric standard model (mssm). a plausible option is to introduce a new supersymmetric sector coupled to the mssm higgs fields, whose associated states resolve the little hierarchy problem between the third generation soft parameters and the weak scale. susy also accomodates a weakly interacting cold dark matter (dm) candidate in the form of a stable neutralino. in minimal realizations, the thus-far null results of direct dm searches, along with the dm relic abundance constraint, introduce a level of fine-tuning as severe as the one due to the susy little hierarchy problem. we analyse the generic implications of new susy sectors parametrically heavier than the minimal susy spectrum, devised to increase the higgs boson mass, on this "little neutralino dm problem". we focus on the susy operator of smallest scaling dimension in an effective field theory description, which modifies the higgs and dm sectors in a correlated manner. within this framework, we show that recent null results from the lux experiment imply a tree-level fine-tuning for gaugino dm which is parametrically at least a few times larger than that of the mssm. higgsino dm whose relic abundance is generated through a thermal freeze-out mechanism remains also severely fine-tuned, unless the dm lies below the weak boson pair-production threshold. as in the mssm, well-tempered gaugino-higgsino dm is strongly disfavored by present direct detection results. | the dark side of electroweak naturalness beyond the mssm |
finding signatures of dark matter in transport characteristics of solids would be an important step on the road to detect this illusive component of the mass of our universe. this is especially important and timely as the experiments designed to directly detect dark matter particles continue to provide negative results. as a first step in this direction we consider topologically nontrivial weyl or dirac semimetals and derive the modified kinetic equation taking into account two coupled u (1 )-gauge fields, one being the standard maxwell electromagnetic field and other corresponding to the dark sector. the resulting boltzmann kinetic equation is modified by the berry curvature which couples to both visible and dark sector gauge fields. it was revealed that the dark sector induces modifications of transport coefficients due to the appearance of coupling constant between gauge fields and dark sector magnetic field. | chiral kinetic theory in the presence of dark photon |
astaroth is a novel r&d project which aims at improving the physics reach of future direct dark matter detection experiments based on nai(tl) scintillating crystals. there is a strong need to test the long standing dama positive observation of an annual modulation that could be due to dark matter (dm), with the same target material and in a model independent way. astaroth aim is the enhancement of the sensitivity to the annual modulation signal, compared with present technology, by lowering the detection energy threshold in order to observe sub-kev recoils for the first time. this can be achieved by reading the scintillation light from the nai(tl) crystals with arrays of silicon photomultipliers (sipm), and placing the detectors in a cryogenic environment. sipms feature lower dark noise than photomultiplier tubes (pmts) at t < 150 k and allow for higher light collection. the cooling medium is liquid argon, as it is an excellent scintillator that can be instrumented to act as a veto against several backgrounds. | the astaroth project: enhanced low-energy sensitivity to dark matter annual modulation |
the picasso and coupp collaborations use superheated liquid detectors to search for cold dark matter through the direct detection of weakly interacting massive particles (wimps). these experiments, located in the underground laboratory of snolab, canada, detect phase transitions triggered by nuclear recoils in the kev range induced by interactions with wimps. we present details of the construction and operation of these detectors as well as the results, obtained by several years of observations. we also introduce pico, a joint effort of the two collaborations to build a second generation ton-scale bubble chamber with 250 liters of active liquid. | picasso, coupp and pico - search for dark matter with bubble chambers |
neutrons are a particularly dangerous background for direct wimp dark matter searches; their nuclear recoils with the target nuclei are often indistinguishable from nuclear recoils produced by wimp-nuclear collisions. in this study, we explore the concept of a liquid scintillator neutron veto detector that would allow direct dark matter detectors to potentially reject neutrons with greater than 99% efficiency. here we outline the construction and testing of a small prototype detector and the potential implications of this technology for future dark matter detectors. | a prototype neutron veto for dark matter detectors |
recent results from direct detection experiments such as lux, pandax-ii and xenon100 have imposed severe constraints on the multi-gev mass window in various dark matter (dm) models. however, many of these experiments are not sensitive to mev scale dm as the corresponding recoil energies are, largely, lower than the detector thresholds. re-examining the light scalar dm in a model-independent approach, we find that while the parameter space can be constrained using cosmological and astrophysical observations, a significantly large fraction is still viable. we further demonstrate 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. | model independent analysis of mev scale dark matter |
we consider the possibility of a gravitational wave signal in an asymmetric dark matter model. in this model a generative sector produces both the baryon asymmetry and a dark matter asymmetry in a strong first-order phase transtion. bubble collisions during the phase transition lead to sound waves in the plasma which are a source of a stochastic gravitational wave background. we consider the prospects of future graviational wave observatories such as lisa and bbo detecting such a signal. constraints on the model from halo ellipticity, $\delta n_{\rm eff}$ and direct detection experiments are also discussed. | generation of asymmetric dark matter and gravitational waves |
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 $m_a c^2$. axion-related excitations are then detected with an upconversion scheme involving a pump laser that converts the absorbed axion energy ($\sim $ hundreds of $\mu$ev) 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 $4f^n$ 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. | laser induced fluorescence for axion dark matter detection: a feasibility study in ylif$_4$:er$^{3+}$ |
a number of proposed experiments aimed at dark matter studies are based on detection of luminescence in liquid argon at 128 nm. existing solid-state photomultipliers do not have the capability to detect emission at 128 nm in the photon counting mode. spectral properties of a new silicon photomultiplier prototype for vacuum ultraviolet registration are presented. the prototype demonstrates the photon detection efficiency about 1% in 112-182 nm range. | sipm prototype for direct vuv registration |
the most successful class of direct detection of wimps with masses from few gev/c2 to tev/c2 have utilized liquid xenon time projection chambers (tpcs). the xenon project adopted dual phase tpcs using ultra-pure liquid xenon as both target and detection medium for wimps. the first ton-scale liquid xenon based tpc, xenon1t, is running at the gran sasso laboratory. with an active mass inside the tpc of 2 tonnes, data were collected for 278.8 days live time. within a fiducial mass of 1.3 tonne, this results in 1.0 tonne×year exposure. in the energy region of interest, the detector exhibits the lowest background ever obtained in direct dark matter search experiment. in these data no significant excess over background is found and the most stringent limits on wimp-nucleon spin-independent elastic scattering cross section has been set for masses above 6 gev/c2 with a minimum of 4.1×10-47cm2 at 30 gev/c2. | latest results from the xenon1t experiment |
the effective field theory (eft) for dark matter (dm) has been widely used to investigate dark matter detection in both theoretical prediction and experimental analysis. to form a complete basis of effective operators for dirac dm eft at dimension seven, eight new four-fermion operators with a derivative in dm currents have recently been introduced. we discuss the experimental observables and constraints for the theoretical predictions of these new operators to constrain the dm mass and relevant energy scale. the observables from thermal relic abundance, indirect and direct detection, and lhc constraints are presented. | constraints on dimension-seven operators with a derivative in effective field theory for dirac dark matter |
the proposed news apparatus, a spherical detector with a small central electrode sensor operating as a proportional counter, promises to explore new swaths of the direct detection parameter space in the gev and sub-gev dark matter particle mass range by employing very light nuclear targets, such as h and he, and by taking advantage of a very low (sub-kev) energy threshold. here we discuss and study two example classes of dark matter models that will be tested with news: gev-scale millicharged dark matter, and a gev-dirac fermion dark matter model with a light (mev-gev) scalar or vector mediator, and indicate the physical regions of parameter space the experiment can probe. | good news for gev dark matter searches |
detection of uv photons is becoming increasingly necessary with the use of noble gases and liquids in elementary particle experiments. cerenkov light in crystals and glasses, scintillation light in neutrino, dark matter, and rare decay experiments all require sensitivity to uv photons. new sensor materials are needed that can directly detect uv photons and/or absorb uv photons and re-emit light in the visible range measurable by existing photosensors. it has been shown that silicon nanoparticles are sensitive to uv light in a wavelength range around ~ 200 nm. uv light is absorbed and re-emitted at wavelengths in the visible range depending on the size of the nanoparticles. initial tests of the wavelength-shifting properties of silicon nanoparticles are presented here that indicate by placing a film of nanoparticles in front of a standard visible-wavelength detecting photosensor, the response of the sensor is significantly enhanced at wavelengths < 320 nm. | enhanced uv light detection using wavelength-shifting properties of silicon nanoparticles |
we consider scenarios where dark matter (dm) particles carry baryon and/or lepton numbers, which can be defined if there exist operators connecting the dark to the visible sector. as a result, the dm fields become intimately linked to the standard model (sm) ones and can be maximally asymmetric just like the ordinary matter. in particular, we discuss minimal scenarios where the dm is a complex scalar or a dirac fermion coupled to operators with nonzero baryon and/or lepton numbers, and that consist of only sm fields. we consider an initial asymmetry stored in either the sm or the dm sector; the main role of these operators is to properly share the asymmetry between the two sectors, in accordance with observations. after the chemical decoupling, the dm and sm sectors do not care about each other as there is only an ineffective communication between them. once the dm mass is specified, the wilson coefficients of these operators are fixed by the requirement of the correct transfer of the asymmetry. we study the phenomenology of this framework at colliders, direct detection and indirect detection experiments. in particular, the lhc phenomenology is very rich and can be tested in different channels such as the two same-sign leptons with two jets, monojet and monojet with a monolepton. | sharing but not caring: dark matter and the baryon asymmetry of the universe |
charged particles scattering on moving inhomogenities of the magnetised interstellar medium can gain energy through the process of second-order fermi acceleration. this energy gain depletes in turn the magnetic wave spectrum around the resonance wave-vector k~ 1/rl, where rl is the larmor radius of the charged particle. this energy transfer can prohibit the cascading of magnetic turbulence to smaller scales, leading to a drop in the diffusion coefficient and allowing the efficient exchange of charged dark matter particles in the disk and the halo. as a result, terrestial limits from direct detection experiments apply to charged dark matter. together with the no-observation of a drop in the diffusion coefficient, this excludes charged dark matter for 103 gevlesssim m/q lesssim 1011 gev, even if the charged dark matter abundance is only a small part of the total relic abundance. | reacceleration of charged dark matter |
the dark matter problem is one of the most pressing problems in modern physics. as there is no well-established claim from a direct detection experiment supporting the existence of the illusive dark matter that has been postulated to explain the flat rotation curves of galaxies, and since the whole issue of an alternative theory of gravity remains controversial, it may be worth to reconsider the familiar ground of general relativity (gr) itself for a possible way out. it has recently been discovered that a skew-symmetric rank-three tensor field - the lanczos tensor field - that generates the weyl tensor differentially, provides a proper relativistic analogue of the newtonian gravitational force. by taking account of its conformal invariance, the lanczos tensor leads to a modified acceleration law which can explain, within the framework of gr itself, the flat rotation curves of galaxies without the need for any dark matter whatsoever. | can a tensorial analogue of gravitational force explain away the galactic rotation curves without dark matter? |
we examine the leptophilic two-higgs-doublet model with fermionic dark matter, considering the range of experimental constraints on the higgs sector. the measurements of the 125 gev higgs from the lhc run i allow us to focus on those remaining processes that may play an important role at colliders. we find that the leptophilic model allows for a much lighter higgs than in other two-higgs models, although discovery at the lhc will be difficult. adding a dark matter sector motivated by supersymmetric extensions of the leptophilic model, we find the existing parameter space can accommodate constraints from direct detection and the invisible widths of the higgs and z , while also fitting the galactic center gamma ray excess reported by analyses of fermi-lat data. we also discuss the status of the fully supersymmetric version of such models, which include four higgs doublets and a natural dark matter candidate. | dark matter in leptophilic higgs models after the lhc run i |
the current results of direct dark matter searches are controversial. the long-standing dark-matter claim from the dama/libra collaboration is excluded by null-results of several other experiments. however, a comparison of the results by experiments with different detector materials introduces model dependencies. the r&d project cosinus (cryogenic observatory for signatures seen in next-generation underground searches) aims to develop cryogenic detectors based on (hygroscopic) sodium iodide (nai). if successful, such detectors could be used in future experiments to investigate the origin of the annual modulation signal seen by the nai-based scintillation detectors of the dama/libra experiment. cosinus detectors should be able to simultaneously detect phonons and scintillation light produced by a particle interaction inside the nai crystal. this technique allows for an active suppression of β/γ backgrounds as well as detailed studies of a large variety of dark-matter models predicting nuclear interactions. for such kind of studies only moderate exposures of ≲ 100 kg-days are needed. in addition to the projected sensitivities of cosinus detectors, we also show the result of first tests using (only mildly hygroscopic) caesium iodide (csi) crystals as target material. for this measurement we achieved an energy threshold of ∼4.7 kev for nuclear recoils. | the cosinus project: development of new nai-based cryogenic detectors for direct dark matter search |
we review the interplay between collider searches for vector-like quarks and dark matter direct detection experiments in composite higgs models. with focus on a future 100 tev collider, we also extend previous analyses to improve the reach for heavy quarks in the low mass region. | interplay between collider searches for vector-like quarks and dark matter searches in composite higgs models |
in this paper, we revisit the expressions for the (double) differential event rates for elastic wimp-nucleus scattering and discuss some unusual thoughts on (the incompleteness of) the uses of these expressions in (directional) direct dark matter detection physics. several not-frequently mentioned (but important) issues will be argued and demonstrated in detail. | some thoughts on (the incompleteness of) the (double) differential event rates for elastic wimp-nucleus scattering in (directional) direct dark matter detection physics |
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