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we briefly review the halo-independent formalism, that allows to compare data from different direct dark matter de- tection experiments without making assumptions on the properties of the dark matter halo. we apply this method to spin-independent wimp-nuclei interactions, for both isospin-conserving and isospin-violating couplings, updating the existing analyses with the addition of the supercdms bound. we point out that this method can be applied to any type of wimp interaction. | update on the halo-independent comparison of direct dark matter detection data |
searches for dark matter at the lhc are commonly described in terms of simplified models with scalar, pseudo-scalar, vector and axial-vector mediators. in this work we explore the constraints imposed on such models from the observed dark matter relic abundance. we present these constraints over a range of mediator masses relevant for the lhc and for future, higher energy colliders. we additionally compute bounds from a photon line search for the decay of a pseudo-scalar mediator to di-photons that includes the mediator mass region near 750 gev. finally, we compare cosmological constraints with the reach of a possible future 100 tev circular hadron collider, indirect, and direct detection experiments. | cosmological constraints on dark matter models for collider searches |
sabre (sodium-iodide with active background rejection) is a new nai(tl) experiment designed to search for galactic dark matter through the annual modulation signature. sabre will consist of highly pure nai(tl) crystals operated in an active liquid scintillator veto. the sabre experiment will follow a two-phase approach. in the first phase, one high-purity nai(tl) crystal will be operated at lngs in an active liquid scintillator veto with the goal of demonstrating backgrounds low enough for a sensitive test of the dama/libra result. an unprecedented radio-purity for both the nai powder and the crystal growth will be needed to achieve this goal. the second phase will consist in building two high-purity nai(tl) detector arrays, with a total mass of about 50 kg each, located at lngs and in the stawell gold mine in australia. the operation of twin full-scale experiments in both the northern and the southern hemispheres will strengthen the reliability of the result against any possible seasonal systematic effect. | sabre: dark matter annual modulation detection in the northern and southern hemispheres |
we show that for a relatively light majoron (ll 100 ev) non-thermal production from topological defects is an efficient production mechanism. taking the type i seesaw as benchmark scheme, we estimate the primordial majoron abundance and determine the required parameter choices where it can account for the observed cosmological dark matter. the latter is consistent with the scale of unification. possible direct detection of light majorons with future experiments such as ptolemy and the formation of boson stars from the majoron dark matter are also discussed. | light majoron cold dark matter from topological defects and the formation of boson stars |
the evidence for the dark matter (dm) of the hot big bang cosmology is about as good as it gets in natural science. the exploration of its nature is now led by direct and indirect detection experiments, to be complemented by advances in the full range of cosmological tests, including judicious consideration of the rich phenomenology of galaxies. the results may confirm ideas about dm already under discussion. if we are lucky, we also will be surprised once again. | dark matter |
measurements from the gaia satellite have greatly increased our knowledge of the dark matter velocity distributions in the solar neighborhood. there is evidence for multiple cold structures nearby, including a high-velocity stream counterrotating relative to the sun. this stream could significantly alter the spectrum of recoil energies and increase the annual modulation of dark matter in direct detection experiments such as uc(dama/libra). we reanalyze the experimental limits from uc(xenon1t), uc(cdmslite), pico-60, and cosine-100, and compare them to the results of the uc(dama/libra) experiment. while we find that this new component of the dark matter velocity distribution can greatly improve the fit to the uc(dama/libra) data, both spin-independent and spin-dependent interpretations of the uc(dama/libra) signal with elastic and inelastic scattering continue to be ruled out by the null results of other experiments, in particular uc(xenon1t). | direct detection anomalies in light of g a i a data |
we revisit the $l_\mu - l_\tau$ extension of the standard model that can simultaneously address anomalies in semileptonic $b$ meson decays and the nature of dark matter (dm). in the region favored by the $b$ anomalies, this scenario is excluded by a combination of low-energy flavor constraints and stringent dm direct detection constraints if the kinetic mixing between $z^\prime$ gauge boson and the photon vanishes at high energy scales, since this leads to a sizable coupling between dm and the sm in low-momentum scattering processes. however, this is no longer the case if the kinetic mixing vanishes at low energy scales instead. in this scenario, the low-momentum dm scattering rate can be suppressed and constraints from direct detection experiments can be substantially relaxed. as a result, we find a re-opening of the region of parameter space where the $b$ anomalies and dm can be simultaneously explained. | $b$ anomalies and dark matter in an $l_\\mu-l_\\tau$ model with general kinetic mixing |
as liquid xenon tpcs increase in target mass while pursuing the direct detection of wimp dark matter, the technical challenges arising due to their size call for new solutions and open the discussion on alternative detector concepts. proportional scintillation in liquid xenon allows for a single-phase design evading problems related to the liquid-gas interface and the precise gas gap required in a dual-phase tpc. aside from a different scintillation mechanism, the successful detection- and analysis scheme of state-of-the-art experiments is maintained in this approach. we study the impact on charge signal analysis in a single-phase detector of darwin dimensions, where the fast timing of the proportional scintillation signal allows for the precise identification of the single electrons in the ionisation signal. such a discrete electron-counting approach can lead to a better signal resolution for low energies when compared to the classical dual-phase continuous method. the absence of the liquid-gas interface can further benefit the s2-only energy resolution significantly. this can reduce the uncertainties from the scintillation and signal-detection process to a level significantly below the irreducible fluctuation in the primary ionisation. exploiting the precise electron arrival time information can further allow for a powerful single vs. multiple site interaction discrimination with 93% rejection efficiency and 98% signal acceptance. this outperforms the design goal of the darwin observatory by a reduction factor of 4.2 in non-rejected multiple site neutron events. | prospects of charge signal analyses in liquid xenon tpcs with proportional scintillation in the liquid phase |
we propose a new method for the discrimination of sub-micron nuclear recoil tracks from instrumental background in fine-grain nuclear emulsions used in the directional dark matter search. the proposed method uses a 3d convolutional neural network, whose parameters are optimised by bayesian search. unlike previous studies focused on extracting the directional information, we focus on the signal/background separation exploiting the polarisation dependence of the localised surface plasmon resonance phenomenon. comparing the proposed method with the conventional cut-based approach shows a significant boost in the reduction factor for given signal efficiency. | deep learning for direct dark matter search with nuclear emulsions |
we consider the possibility that neutrino masses arise from the exchange of dark matter states. we examine in detail the phenomenology of fermionic dark matter in the singlet-triplet scotogenic model. we explore the case of singlet-like fermionic dark matter, taking into account all coannihilation effects relevant for determining its relic abundance, such as fermion-fermion and scalar-fermion coannihilation. although this in principle allows for dark matter below 60 gev, the latter is in conflict with charged lepton flavour violation (clfv) and/or collider physics constraints. we examine the prospects for direct dark matter detection in upcoming experiments up to 10 tev. fermion-scalar coannihilation is needed to obtain viable fermionic dark matter in the 60-100 gev mass range. fermion-fermion and fermion-scalar coannihilation play complementary roles in different parameter regions above 100 gev. | phenomenological profile of scotogenic fermionic dark matter |
direct detection experiments are looking for nuclear recoils from scattering of sub-gev dark matter (dm) in crystals, and have thresholds as low as ~ 10 ev or dm masses of ~ 100 mev. future experiments are aiming for even lower thresholds. at such low energies, the free nuclear recoil prescription breaks down, and the relevant final states are phonons in the crystal. scattering rates into single as well as multiple phonons have already been computed for a harmonic crystal. however, crystals typically exhibit some anharmonicity, which can significantly impact scattering rates in certain kinematic regimes. in this work, we estimate the impact of anharmonic effects on scattering rates for dm in the mass range ~ 1-10 mev, where the details of multiphonon production are most important. using a simple model of a nucleus in a bound potential, we find that anharmonicity can modify the scattering rates by up to two orders of magnitude for dm masses of o(mev). however, such effects are primarily present at high energies where the rates are suppressed, and thus only relevant for very large dm cross sections. we show that anharmonic effects are negligible for masses larger than ~ 10 mev. | anharmonic effects in nuclear recoils from sub-gev dark matter |
we analyze interactions between dark matter and standard model particles with spin one mediators in an effective field theory framework. in this paper, we are considering dark particles masses in the range from a few mev to the mass of the z boson. we use bounds from different experiments: z invisible decay width, relic density, direct detection experiments, and indirect detection limits from the search of gamma-ray emissions and positron fluxes. we obtain solutions corresponding to operators with antisymmetric tensor mediators that fulfill all those requirements within our approach. | effective field theory analysis of dark matter-standard model interactions with spin one mediators |
two-phase noble liquid detectors, with large target masses and effective background reduction, are currently leading the dark matter direct detection for wimp masses above a few gev. due to their sensitivity to single ionized electron signals, these detectors were shown to also have strong constraints for sub-gev dark matter via their scattering on electrons. in fact, the most stringent direct detection constraints for sub-gev dark matter down to as low as 5 mev come from noble liquid detectors, namely xenon10, darkside-50, xenon100 and xenon1t, although these experiments still suffer from high background at single or a few electron level. lbeca is a planned 100-kg scale liquid xenon detector with significant reduction of the single and a few electron background. the experiment will improve the sensitivity to sub-gev dark matter by three orders of magnitude compared to the current best constraints. | lbeca: a low background electron counting apparatus for sub-gev dark matter detection |
cryogenic rare event search with superconducting thermometers (cresst) is a long-standing direct dark matter detection experiment with cryogenic detectors located at the underground facility laboratori nazionali del gran sasso in italy. cresst-iii, the third generation of cresst, was specifically designed to have a world-leading sensitivity for low-mass dark matter (dm) (less than 2 gev/c2) to probe the spin-independent dm-nucleus cross section. at present, a large part of the parameter space for spin-independent scattering off nuclei remains untested for dark matter particles with masses below few gev/c2 although many motivated theoretical models having been proposed. the cresst-iii experiment employs scintillating cawo4 crystals of ∼ 25 g as target material for dark matter interactions operated as cryogenic scintillating calorimeters at ∼ 10 mk. cresst-iii first data taking was successfully completed in 2018, achieving an unprecedented energy threshold for nuclear recoils. this result extended the present sensitivity to dm particles as light as ∼ 160 mev/c2. in this paper, an overview of the cresst-iii detectors and results will be presented. | searches for light dark matter with the cresst-iii experiment |
the dark matter direct detection rates are highly correlated with the phase space distribution of dark matter particles in our galactic neighbourhood. in this paper we make a systematic study of the impact of astrophysical uncertainties on electron recoil events at the direct detection experiments with xenon and semiconductor detectors. we find that within the standard halo model there can be up to ∼50 % deviation from the fiducial choice in the exclusion bounds from these observational uncertainties. for non-standard halo models we report a similar deviation from the fiducial standard halo model when fitted with recent cosmological n-body simulations while even larger deviations are obtained in case of the observational uncertainties. | halo uncertainties in electron recoil events at direct detection experiments |
the seesaw and leptogenesis commonly depend on the masses of the same particles and thus are both realized at the same scale. in this work, we demonstrate a new possibility to realize a tev-scale neutrino seesaw and a natural high-scale leptogenesis. we extend the standard model by two gauge-singlet scalars, a vectorlike isodoublet fermion and one isotriplet higgs scalar. our model respects a softly broken lepton number and an exactly conserved z2 discrete symmetry. it can achieve three things altogether: (i) realizing a testable type-ii seesaw at the tev scale with two nonzero neutrino mass eigenvalues, (ii) providing minimal inelastic dark matter from the new fermion doublets, and (iii) accommodating a thermal or nonthermal leptogenesis through the singlet scalar decays. we further analyze the current experimental constraints on our model and discuss the implications for the dark matter direct detections and the lhc searches. | tev-scale neutrino mass generation, minimal inelastic dark matter, and high scale leptogenesis |
we study the phenomenological credibility of a vectorial dark matter, coupled to a z' portal through chern-simons interaction. we scrutinize two possibilities of connecting a z' with the standard model: (1) through kinetic mixing and (2) from a second chern-simons interaction. both scenarios are characterized by suppressed nuclear recoil scatterings, rendering direct detection searches not promising. indirect detection experiments, on the other hand, furnish complementary limits for tev scale masses, specially with the cta. searches for mono-jet and dileptons signals at the lhc are important to partially probe the kinetic mixing setup. finally we propose an uv completion of the chern-simons dark matter framework. | z' portal to chern-simons dark matter |
the cryogenic dark matter search low ionization threshold experiment (cdmslite) achieved efficient detection of very small recoil energies in its germanium target, resulting in sensitivity to lightly ionizing particles (lips) in a previously unexplored region of charge, mass, and velocity parameter space. we report first direct-detection limits calculated using the optimum interval method on the vertical intensity of cosmogenically produced lips with an electric charge smaller than e /(3 ×105), as well as the strongest limits for charge ≤e /160 , with a minimum vertical intensity of 1.36 ×10-7 cm-2 s-1 sr-1 at charge e /160 . these results apply over a wide range of lip masses (5 mev /c2 to 100 tev /c2 ) and cover a wide range of β γ values (0.1 - 106 ), thus excluding nonrelativistic lips with β γ as small as 0.1 for the first time. | constraints on lightly ionizing particles from cdmslite |
we perform a systematic study of the electric and magnetic dipole moments of dark matter (dm) that are induced at the one-loop level when dm experiences four-fermion interactions with standard model (sm) charged fermions. related to their loop nature these moments can largely depend on the uv completion at the origin of the four-fermion operators. we illustrate this property by considering explicitly two simple ways to generate these operators, from t- or s-channel tree-level exchange. fixing the strength of these interactions from the dm relic density constraint, we obtain in particular a magnetic moment that, depending on the interaction considered, lies typically between 10−20 to 10−23 ecm or identically vanishes. these non-vanishing values induce, via photon exchange, dm-nucleus scattering cross sections that could be probed by current or near future direct detection experiments. | dark matter electromagnetic dipoles: the wimp expectation |
we revisit the detection of luminous dark matter in direct detection experiments. in this scenario, dark matter scatters endothermically to produce an excited state, which decays to produce a photon. we explore ways in which the electron recoil signal from the decay photon can be differentiated from other potential electron recoil signals with a narrow spectral shape. we find that larger volume/exposure xenon detectors will be unable to differentiate the signal origin without significant improvements in detector energy resolution of around an order of magnitude. we also explore what can be learned about a generic luminous dark matter signal with a higher resolution detector. motivated by the advancements in energy resolution by solid-state detectors, we find that sub-ev resolution enables the discovery of ldm in the presence of background levels that would otherwise make observation impossible. we also find that sub-ev resolution can be used to determine the shape of the luminous dark matter decay spectrum and thus constrain the dark matter mass and velocity distribution. | low-mass dark matter (in)direct detection with inelastic scattering |
(α,n) reactions play an important role in nuclear astrophysics and applications and are an important background source in neutrino and dark matter detectors. measurements of total (α,n) cross sections employing direct neutron detection often have a considerable systematic uncertainty associated with the energy-dependent neutron detection efficiency and the unknown initial neutron energy distribution. the 3he bf3 giant barrel (hebgb) neutron detector was built at the edwards accelerator laboratory at ohio university to overcome this challenge. hebgb offers a near-constant neutron detection efficiency of (7.5 ± 1.2)% over the neutron energy range 0.01 mev-9.00 mev, removing a significant source of systematic uncertainty present in earlier (α,n) cross section measurements. | the 3he bf3 giant barrel (hebgb) neutron detector |
we summarize the evidence for dm-like anomalies in neutron multiplicity spectra collected underground with pb targets by three independent experiments: nemesis (at 210 m.w.e.) nmds (at 583 m.w.e.), and zeplin-ii (at 2850 m.w.e.). a new analysis shows small but persistent anomalies at high neutron multiplicities. adjusted for differences in detection efficiencies, the positions of the anomalies are consistent between the three systems. also, the intensities match when corrected for the acquisition time and estimated detection efficiency. while the three measurements are inconclusive when analyzed separately, together, they exclude a statistical fluke to better than one in a million. to prove the existence of the anomalies above the 5-sigma discovery threshold, we propose to upgrade the current nemesis setup. the upgrade concept and the critical components of the new experiment are described. the upgraded setup would already acquire the needed data sample during the first year of operation. additional information, vital for the physics interpretation of the analysis, will be obtained with a cu target. | nemesis setup for indirect detection of wimps |
quantum mechanics allows for states in macroscopic superpositions, but they ordinarily undergo rapid decoherence due to interactions with their environment. a system that only interacts gravitationally, such as an arrangement of dark matter (dm), may exhibit slow decoherence. in this letter, we compute the decoherence rate of a quantum object within general relativity, focusing on superposed metric oscillations; a rare quantum general relativistic result. for axion dm in a superposition of the field's phase, we find that dm in the milky way is robust against decoherence, while a spatial superposition is not. this novel phase behavior may impact direct detection experiments. | general relativistic decoherence with applications to dark matter detection |
direct detection of nuclear scatterings of sub-gev dark matter (dm) particles favors low-z nuclei. hydrogen nucleus, which has a single proton, provides the best kinematic match. the characteristic nuclear recoil energy is boosted by a factor of a few tens from those for larger nuclei used in traditional weakly interacting massive particles searches. furthermore, hydrogen is optimal for detecting spin-dependent nuclear scatterings of sub-gev dm, where large parameter space still remains unconstrained yet. in this paper, we first introduce several hydrogen-rich targets, which emit two classes of signals under kinetic excitations. one class of the signals is infrared photons, which are from fundamental vibrational and rotational modes of molecules and at several characteristic wavelengths. another is acoustic phonons and optical phonons that decay into acoustic phonons. we then discuss the technical status and future researches of low-tc transition-edge sensor (tes) detectors, which measure the infrared photons and acoustic phonons with desirable sensitivities. utilization of hydrogen-rich targets and ultra-sensitive low-tc tes detectors for light dm detection requires both theoretical modeling and experimental prototyping. | light dark matter detection with hydrogen-rich targets and low-tc tes detectors |
direct detection experiments are gaining in mass reach. here we show that the inclusion of dark compton scattering, which has typically been neglected in absorption searches, has a substantial impact on the reach and discovery potential of direct detection experiments at high bosonic cold dark matter masses. we demonstrate this for relic dark photons and axionlike particles: we improve expected reach across materials, and further use results from supercdms, edelweiss, and gerda to place enhanced limits on dark matter parameter space. we outline the implications for detector design and analysis. | impact of dark compton scattering on direct dark matter absorption searches |
the dual-phase xenon time projection chamber (tpc) is a leading detector technology in rare event searches for dark matter and neutrino physics. the success of this type of detector technology relies on its capability to detect both primary scintillation and ionization signals from particle interactions in liquid xenon (lxe). the ionization electrons are converted into electroluminescence in the gas xenon (gxe), where a single electron can be amplified by more than 100 times in number of photons in a strong electric field. maintaining a strong and uniform electric field in the small gas gap in large diameter tpcs is challenging. one alternative solution is to produce the electroluminescence in the lxe directly to overcome the gas gap uniformity problem. here we report on the design and performance of a single-phase radial tpc (rtpc) which can create and detect the electroluminescence directly in lxe. it simplifies the design and operation of the lxe tpc by using a single wire in the axial center to create the strong electric field. we present the performance of such an rtpc and discuss its limitations for potential applications. | performance of a radial time projection chamber with electroluminescence in liquid xenon |
photon detection is important for liquid argon detectors for direct dark matter searches or neutrino property measurements. precise simulation of photon transport is widely used to understand the probability of photon detection in liquid argon detectors. traditional photon transport simulation, which tracks every photon using the geant4 simulation toolkit, is a major computational challenge for kilo-tonne-scale liquid argon detectors and gev-level energy depositions. in this work, we propose a one-dimensional generative model which efficiently generates features using an $\mathrm{outerproduct}$ -layer. this model bypasses photon transport simulation and predicts the number of photons detected by particular photon detectors at the same level of detail as the geant4 simulation. the application to simulating photon detection systems in kilo-tonne-scale liquid argon detectors demonstrates this novel generative model is able to reproduce geant4 simulation with good accuracy and 20 to 50 times faster. this generative model can be used to quickly predict photon detection probability in huge liquid argon detectors like protodune or dune. | photon detection probability prediction using one-dimensional generative neural network |
we compare the general effective theory of one-body dark matter nucleon interactions to current direct detection experiments in a global multidimensional statistical analysis. we derive exclusion limits on the 28 isoscalar and isovector coupling constants of the theory, and show that current data place interesting constraints on dark matter-nucleon interaction operators usually neglected in this context. we characterize the interference patterns that can arise in dark matter direct detection from pairs of dark matter-nucleon interaction operators, or from isoscalar and isovector components of the same operator. we find that commonly neglected destructive interference effects weaken standard direct detection exclusion limits by up to one order of magnitude in the coupling constants. | global limits and interference patterns in dark matter direct detection |
xmass is a multipurpose liquid-xenon detector that currently aims to directly detect dark matter. in this paper, we describe the fabrication and characterization of reference sources used for the energy calibration and position reconstruction of the present xmass detector. several gamma-ray sources were produced in the form of a sealed needle-source. a thin-wall tube with a diameter of approximately 0.2 mm was sealed at both ends, with the 241am or 57co source material contained inside. the active region of the source was observed to be 1-2 mm long, close to the tip of the needle. these sources were tested in the xmass detector, and the results were compared with monte-carlo simulations. | micro-source development for xmass experiment |
we propose a new strategy to search for a particular type of dark matter via nuclear capture. if the dark matter particle carries baryon number, as motivated by a class of theoretical explanations of the matter-antimatter asymmetry of the universe, it can mix with the neutron and be captured by an atomic nucleus. the resulting state de-excites by emitting a single photon or a cascade of photons with a total energy of up to several mev. the exact value of this energy depends on the dark matter mass. we investigate the prospects for detecting dark matter capture signals in current and future neutrino and dark matter direct detection experiments. | dark matter capture by atomic nuclei |
from an assumed signal in a dark matter (dm) direct detection experiment a lower bound on the product of the dm-nucleon scattering cross section and the local dm density is derived, which is independent of the local dm velocity distribution. this can be combined with astrophysical determinations of the local dm density. within a given particle physics model the bound also allows a robust comparison of a direct detection signal with limits from the lhc. furthermore, the bound can be used to formulate a condition which has to be fulfilled if the particle responsible for the direct detection signal is a thermal relic, regardless of whether it constitutes all dm or only part of it. we illustrate the arguments by adopting a simplified dm model with a z' mediator and assuming a signal in a future xenon direct detection experiment. | halo-independent tests of dark matter direct detection signals: local dm density, lhc, and thermal freeze-out |
we investigate catalysis of electroweak baryogenesis by fermionic higgs portal dark matter using a two higgs doublet model augmented by vector-like fermions. the lightest neutral fermion mass eigenstate provides a viable dark matter candidate in the presence of a stabilizing symmetry z_2 or gauged u(1)_d symmetry. allowing for a non-vanishing cp-violating phase in the lowest-dimension higgs portal dark matter interactions allows generation of the observed dark matter relic density while evading direct detection bounds. the same phase provides a source for electroweak baryogenesis. we show that it is possible to obtain the observed abundances of visible and dark matter while satisfying present bounds from electric dipole moment (edm) searches and direct detection experiments. improving the present electron (neutron) edm sensitivity by one (two) orders of magnitude would provide a conclusive test of this scenario. | catalysis of electroweak baryogenesis via fermionic higgs portal dark matter |
dark matter can scatter and excite a nucleus to a low-lying excitation in a direct detection experiment. this signature is distinct from the canonical elastic scattering signal because the inelastic signal also contains the energy deposited from the subsequent prompt de-excitation of the nucleus. a measurement of the elastic and inelastic signal will allow a single experiment to distinguish between a spin-independent and spin-dependent interaction. for the first time, we characterise the inelastic signal for two-phase xenon detectors in which dark matter inelastically scatters off the 129xe or 131xe isotope. we do this by implementing a realistic simulation of a typical tonne-scale two-phase xenon detector and by carefully estimating the relevant background signals. with our detector simulation, we explore whether the inelastic signal from the axial-vector interaction is detectable with upcoming tonne-scale detectors. we find that two-phase detectors allow for some discrimination between signal and background so that it is possible to detect dark matter that inelastically scatters off either the 129xe or 131xe isotope for dark matter particles that are heavier than approximately 010 gev . if, after two years of data, the xenon1t search for elastic scattering nuclei finds no evidence for dark matter, the possibility of ever detecting an inelastic signal from the axial-vector interaction will be almost entirely excluded. | prospects for dark matter detection with inelastic transitions of xenon |
recently we studied the direct detection of multi-component dark matter with arbitrary local energy densities. although the generation of the dark matter relic abundance is model-dependent, and in principle could be only indirectly related to direct detection, it is interesting to consider the implications of the former on the latter. in this work we conduct an extended analysis to include constraints from two natural scenarios of dark matter genesis: asymmetric dark matter and thermal freeze-out. in the first (second) case, the dark matter number (energy) densities of the different components are expected to be similar. in the case of thermal freeze-out, we assume that the global energy density scales with the local one. in our numerical analysis we analyse the median sensitivity of direct detection experiments to discriminate a two-component scenario from a one-component one, and also the precision with which dark matter parameters can be extracted. we analyse these generic scenarios for both light and heavy mediators. we find that most scenarios have a relatively suppressed maximum median sensitivity compared to the previously studied general cases. we also find that the asymmetric scenario is more promising than the thermal freeze-out one. | on the direct detection of multi-component dark matter: implications of the relic abundance |
in multi-component scalar dark matter scenarios, a single zn (n ≥ 4) symmetry may account for the stability of different dark matter particles. here we study the case where n is even (n = 2n) and two species, a complex scalar and a real scalar, contribute to the observed dark matter density. we perform a phenomenological analysis of three scenarios based on the z4 and z6 symmetries, characterizing their viable parameter spaces and analyzing their detection prospects. our results show that, thanks to the new interactions allowed by the z2n symmetry, current experimental constraints can be satisfied over a wider range of dark matter masses, and that these scenarios may lead to observable signals in direct detection experiments. finally, we argue that these three scenarios serve as prototypes for other two-component z2n models with one complex and one real dark matter particle. | two-component scalar dark matter in z2n scenarios |
we study simple effective models of fermionic wimp dark matter, where the dark matter candidate is a mixture of a standard model singlet and an n-plet of su2 lwith n ≥ 3, stabilized by a discrete symmetry. the dark matter mass is assumed to be around the electroweak scale, and the mixing is generated by higher-dimensional operators, with a cutoff scale ≳tev. for appropriate values of the mass parameters and the mixing we find that the observed dark matter relic density can be generated by coannihilation. direct detection experiments have already excluded large parts of the parameter space, and the next-generation experiments will further constrain these models. | well-tempered n-plet dark matter |
there is no known reason that dark matter interactions with the standard model should couple to neutrons and protons in the same way. this isospin violation can have large consequences, modifying the sensitivity of existing and future direct detection experimental constraints by orders of magnitude. previous works in the literature have focused on the zero-momentum limit which has its limitations when extending the analysis to the non-relativistic effective field theory basis (nreft). in this paper, we study isospin violation in a detailed manner, paying specific attention to the experimental setups of liquid noble detectors. we analyse two effective standard model gauge invariant models as interesting case studies as well as the more model-independent nreft operators. this work demonstrates the high degree of complementarity between the target nuclei xenon and argon. most notably, we show that the standard model gauge-invariant formulation of the standard spin-dependent interaction often generates a sizeable response from argon, a target nuclei with zero spin. this work is meant as an update and a useful reference to model builders and experimentalists. | isospin-violating dark matter at liquid noble detectors: new constraints, future projections, and an exploration of target complementarity |
we propose to split the sparticle spectrum from the hierarchy between the gut scale and the planck scale. a split supersymmetric model, which gives non-universal gaugino masses, is built with proper high dimensional operators in the framework of so(10) gut. based on a calculation of two-loop beta functions for gauge couplings (taking into account all weak scale threshold corrections), we check the gauge coupling unification and dark matter constraints (relic density and direct detections). we find that our scenario can achieve the gauge coupling unification and satisfy the dark matter constraints in some part of parameter space. we also examine the sensitivity of the future xenon1t experiment and find that the currently allowed parameter space in our scenario can be covered for a neutralino dark matter below about 1.0 tev. | a split susy model from susy gut |
decays of radioisotopes on inner detector surfaces can pose a major background concern for the direct detection of dark matter. while these backgrounds are conventionally mitigated with position cuts, these cuts reduce the exposure of the detector by decreasing the sensitive mass, and uncertainty in position determination may make it impossible to adequately remove such events in certain detectors. in this paper, we provide a new technique for substantially reducing these surface backgrounds in liquid argon (lar) detectors, independent of position cuts. these detectors typically use a coating of tetraphenyl-butadiene (tpb) on the inner surfaces as a wavelength shifter to convert vacuum ultraviolet (vuv) lar scintillation light to the visible spectrum. we find that tpb scintillation contains a component with a previously unreported exceptionally long lifetime (∼ms ). we discovered that this component differs significantly in magnitude between alpha, beta, and vuv excitation, which enables the use of pulse shape discrimination to suppress surface backgrounds by more than a factor of 1 03 with negligible loss of dark matter sensitivity. we also discuss how this technique can be extended beyond just lar experiments. | surface background suppression in liquid argon dark matter detectors using a newly discovered time component of tetraphenyl-butadiene scintillation |
anais is a direct dark matter detection experiment aiming at the confirmation or refutation of the dama/libra positive annual modulation signal in the low energy detection rate, using the same target and technique. anais-112, located at the canfranc underground laboratory in spain, is operating an array of 3×3 ultrapure nai(tl) crystals with a total mass of 112.5 kg since august 2017. the trigger rate in the region of interest (1-6 kev) is dominated by non-bulk scintillation events. in order to discriminate these noise events from bulk scintillation events, robust filtering protocols have been developed. although this filtering procedure works very well above 2 kev, the measured rate from 1 to 2 kev is about 50% higher than expected according to our background model, and we cannot discard non-bulk scintillation events as responsible of that excess. in order to improve the rejection of noise events, a boosted decision tree has been developed and applied. with this new pmt-related noise rejection algorithm, the anais-112 background between 1 and 2 kev is reduced by almost 30%, leading to an increase in sensitivity to the annual modulation signal. the reanalysis of the three years of anais-112 data with this technique is also presented. | machine-learning techniques applied to three-year exposure of anais-112 |
for the interpretation of past and future direct searches for dark matter (dm) particles, it is important to be able to provide accurate predictions for event rates and spectra under a variety of possible and viable assumptions in a computationally efficient way. while there exists a few tools to compute dm induced nuclear recoil spectra, 'obscura' is not limited to nuclear targets. instead its main focus lies on sub-gev dm searches probing electron recoils which typically requires methods from atomic and condensed matter physics. in the context of sub-gev dm searches, new ideas such as target materials or detection techniques are being proposed regularly, and the theoretical modelling of these are getting improved continuously. at the same time, currently running experiments continue to publish their results and analyses, setting increasingly strict bounds on the dm parameter space. in such a dynamic field, 'obscura' can be an invaluable tool due to its high level of adaptability and facilitate and accelerate the development of new, reliable research software for the preparation of a dm discovery in the hopefully near future. | obscura: a modular c++ tool and library for the direct detection of (sub-gev) dark matter via nuclear and electron recoils |
results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the mχ-σn plane. recently methods which are independent of the dm halo velocity distribution have been developed which present results in the vmin-g̃ plane, but these in turn require an assumption on the dark matter mass. here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. with a change of variables from vmin to nuclear recoil momentum (pr), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call h̃(pr). the entire family of conventional halo-independent g̃(vmin) plots for all dm masses are directly found from the single h̃(pr) plot through a simple rescaling of axes. by considering results in h̃(pr) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple g̃(vmin) plots for different dm masses. we conduct a sample analysis comparing the cdms ii si events to the null results from lux, xenon10, and supercdms using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity. | halo-independent direct detection analyses without mass assumptions |
in recent decades, inorganic crystals have been widely used in dark matter direct search experiments. to contribute to the understanding of the capabilities of csi(na) and caf2(eu) crystals, a mono-energetic neutron beam is utilized to study the properties of nuclear recoils, which are expected to be similar to signals of dark matter direct detection. the quenching factor of nuclear recoils in csi(na) and caf2eu, as well as an improved discrimination factor between nuclear recoils and γ backgrounds in csi(na), are reported. | neutron beam tests of csi(na) and caf2(eu) crystals for dark matter direct search |
virialized ultra-light fields (vulfs) are viable cold dark matter candidates and include scalar and pseudo-scalar bosonic fields, such as axions and dilatons. direct searches for vulfs rely on low-energy precision measurement tools. while the previous proposals have focused on detecting coherent oscillations of the vulf signals at the vulf compton frequencies at individual devices, here i consider a network of such devices. vulfs are essentially dark matter {\em waves} and as such they carry both temporal and spatial phase information. thereby, the discovery reach can be improved by using networks of precision measurement tools. to formalize this idea, i derive a spatio-temporal two-point correlation function for the ultralight dark matter fields in the framework of the standard halo model. due to vulfs being gaussian random fields, the derived two-point correlation function fully determines $n$-point correlation functions. for a network of $n_{d}$ devices within the coherence length of the field, the sensitivity compared to a single device can be improved by a factor of $\sqrt{n_{d}}$. further, i derive a vulf dark matter signal profile for an individual device. the resulting line shape is strongly asymmetric due to the parabolic dispersion relation for massive non-relativistic bosons. i discuss the aliasing effect that extends the discovery reach to vulf frequencies higher than the experimental sampling rate. i present sensitivity estimates and develop a stochastic field snr statistic. finally, i consider an application of the developed formalism to atomic clocks and their networks. | detecting dark matter waves with precision measurement tools |
we present a measurement of the cosmogenic activation in the cryogenic germanium detectors of the edelweiss iii direct dark matter search experiment. the decay rates measured in detectors with different exposures to cosmic rays above ground are converted into production rates of different isotopes. the measured production rates in units of nuclei/kg/day are 82 ± 21 for 3h, 2.8 ± 0.6 for 49v, 4.6 ± 0.7 for 55fe, and 106 ± 13 for 65zn. these results are the most accurate for these isotopes. a 90% c.l. lower limit on the production rate of 68ge of 71 nuclei/kg/day is also presented. they are compared to model predictions present in literature and to estimates calculated with the activia code. | measurement of the cosmogenic activation of germanium detectors in edelweiss-iii |
the darkside-50 experiment at the laboratori nazionali del gran sasso is a search for dark matter using a dual phase time projection chamber with 50 kg of low radioactivity argon as target. light signals from interactions in the argon are detected by a system of 38 photo-multiplier tubes (pmts), 19 above and 19 below the tpc volume inside the argon cryostat. we describe the electronics which processes the signals from the photo-multipliers, the trigger system which identifies events of interest, and the data-acquisition system which records the data for further analysis. the electronics include resistive voltage dividers on the pmts, custom pre-amplifiers mounted directly on the pmt voltage dividers in the liquid argon, and custom amplifier/discriminators (at room temperature). after amplification, the pmt signals are digitized in caen waveform digitizers, and caen logic modules are used to construct the trigger; the data acquisition system for the tpc is based on the fermilab artdaq software. the system has been in operation since early 2014. | the electronics, trigger and data acquisition system for the liquid argon time projection chamber of the darkside-50 search for dark matter |
we explore the possibility of a beyond the standard model scalar ($\phi$) as a possible explanation of the diphoton resonance at 750~gev invariant mass reported by the atlas and cms collaborations at the large hadron collider (lhc). we first present in a model-independent way the scalar-gluon-gluon and scalar-photon-photon effective couplings needed for obtaining the required diphoton cross-section at the lhc for different total widths. we investigate here two new-physics possibilities that can generate these effective couplings, namely, (i) the 2-higgs-doublet model (2hdm) in the alignment limit, and (ii) a singlet scalar, with vector-like fermions added and playing a crucial role in generating the effective couplings. we present the regions of model parameter space which are allowed by direct lhc and perturbative unitarity constraints, and that give the required diphoton cross-section at the lhc for various total widths. in the singlet case, we include the possibility that $\phi$ decays into a pair of neutral stable vector-like fermions that could be dark matter. we find regions of parameter-space of the singlet model that gives the required diphoton rate, have the correct dark matter relic-density, have dark matter direct-detection rates compatible with current direct-detection experiments, and satisfy lhc bounds and perturbative unitarity constraints. | the 750 gev diphoton excess in a two higgs doublet model and a singlet scalar model, with vector-like fermions, unitarity constraints, and dark matter implications |
the framework of nonrelativistic effective field theory (nreft) aims to generalize the standard analysis of direct detection experiments in terms of spin-dependent and spin-independent interactions. we show that a number of nreft operators lead to distinctive new directional signatures, such as prominent ringlike features in the directional recoil rate, even for relatively low-mass weakly interacting massive particles. we discuss these signatures and how they could affect the interpretation of future results from directional detectors. we demonstrate that considering a range of possible operators introduces a factor of 2 uncertainty in the number of events required to confirm the median recoil direction of the signal. furthermore, using directional detection, it is possible to distinguish the more general nreft interactions from the standard spin-indenpendent/spin-dependent interactions at the 2 σ level with o (100 - 500 ) events. in particular, we demonstrate that for certain nreft operators directional sensitivity provides the only method of distinguishing them from these standard operators, highlighting the importance of directional detectors in probing the particle physics of dark matter. | new directional signatures from the nonrelativistic effective field theory of dark matter |
the standard interpretation of direct-detection limits on dark matter involves particular assumptions of the underlying wimp-nucleus interaction, such as, in the simplest case, the choice of a helm form factor that phenomenologically describes an isoscalar spin-independent interaction. in general, the interaction of dark matter with the target nuclei may well proceed via different mechanisms, which would lead to a different shape of the corresponding nuclear structure factors as a function of the momentum transfer q . we study to what extent different wimp-nucleus responses can be differentiated based on the q -dependence of their structure factors (or "form factors"). we assume an overall strength of the interaction consistent with present spin-independent limits and consider an exposure corresponding to xenon1t-like, xenonnt-like, and darwin-like direct detection experiments. we find that, as long as the interaction strength does not lie too much below current limits, the darwin settings allow a conclusive discrimination of many different response functions based on their q -dependence, with immediate consequences for elucidating the nature of dark matter. | discriminating wimp-nucleus response functions in present and future xenon-like direct detection experiments |
the μev-scale axion is a compelling cold dark matter candidate. the axion dark matter experiment (admx) searches for axions by stimulating the decay of galactic dark matter halo axions into detectable microwave photons by their conversion in a resonant cavity permeated by a strong, static magnetic field. the signal depends on properties of the milky way's dark matter halo; the choice of halo model has significant implications for the sensitivity of direct detection searches, e.g., admx. this paper explores the sensitivity of the data taken by admx from 2008 to 2010 to various dark matter halo models. new models for the phase-space distribution of local axions are considered; the analysis demonstrates that certain assumptions about the dark matter halo improve limits on axion-photon coupling. in addition, new admx data covering 860-892 mhz are included in the analysis. | limits on axion-photon coupling or on local axion density: dependence on models of the milky way's dark halo |
parity (p )-violating pseudoscalar or pseudovector cosmic fields are invoked in different models for cold dark matter or in the standard model extension that allows for lorentz invariance violation. a direct detection of the timelike component of such fields requires a direct measurement of p -odd potentials or their evolution over time. herein, advantageous properties of chiral molecules, in which p -odd potentials lead to resonance frequency differences between enantiomers, for direct detection of such p -odd cosmic field interactions are demonstrated. scaling behavior of electronic structure enhancements of such interactions with respect to nuclear charge number and the fine-structure constant is derived analytically. this allows a simple estimate of the effect sizes for arbitrary molecules. the analytical derivation is supported by quasirelativistic numerical calculations in the molecules h2x2 and h2x o with x = o, s, se, te, or po. parity-violating effects due to cosmic fields on the c-f stretching mode in chbrclf are compared to electroweak parity violation and influences of nonseparable anharmonic vibrational corrections are discussed. on this basis, gaul et al. [phys. rev. lett. 125, 123004 (2020), 10.1103/physrevlett.125.123004] estimated from a 20-year-old experiment with chbrclf that bounds on lorentz invariance violation as characterized by the parameter | b0e| can be pushed down to the order of 10-17gev in modern experiments with suitably selected molecular system, which will be an improvement of the current best limits by at least two orders of magnitude. this serves to highlight the particular opportunities that precision spectroscopy of chiral molecules provides in the search for new physics beyond the standard model. | parity-nonconserving interactions of electrons in chiral molecules with cosmic fields |
we investigate the complex interactions between the stellar disc and the dark-matter halo during bar formation and evolution using n-body simulations with fine temporal resolution and optimally chosen spatial resolution. we find that the forming stellar bar traps dark matter in the vicinity of the stellar bar into bar-supporting orbits. we call this feature the shadow bar. the shadow bar modifies both the location and magnitude of the angular momentum transfer between the disc and dark matter halo and adds 10 per cent to the mass of the stellar bar over 4 gyr. the shadow bar is potentially observable by its density and velocity signature in spheroid stars and by direct dark matter detection experiments. numerical tests demonstrate that the shadow bar can diminish the rate of angular momentum transport from the bar to the dark matter halo by more than a factor of 3 over the rate predicted by dynamical friction with an untrapped dark halo, and thus provides a possible physical explanation for the observed prevalence of fast bars in nature. | dark matter trapping by stellar bars: the shadow bar |
recent cdf ii collaboration results on $w$ mass measurements contradict standard model~(sm) prediction, requiring new physics to explain this anomaly. to explain this issue, in this paper we investigate the idea of using the $u(1)_{b-l}$ gauged sm extension. we demonstrate that $b-l$ extended models can explain the revised best fit values for $s$, $t$, and $u$ following the cdf ii results. we studied the parameter space of models with and without mixing between neutral gauge bosons. we also reviewed the dark matter constraints and demonstrated that there is parameter space which is compatible with current $w$ boson mass, relic abundance, and direct detection experiments. | $b-l$ model in light of the cdf ii result |
rades (relic axion detector exploratory setup) is a project with the goal of directly searching for axion dark matter above the $30 \mu$ev scale employing custom-made microwave filters in magnetic dipole fields. currently rades is taking data at the lhc dipole of the cast experiment. in the long term, the rades cavities are envisioned to take data in the (baby)-iaxo magnet. in this article we report on the modelling, building and characterisation of an optimised microwave-filter design with alternating irises that exploits maximal coupling to axions while being scalable in length without suffering from mode-mixing. we develop the mathematical formalism and theoretical study which justifies the performance of the chosen design. we also point towards the applicability of this formalism to optimise the madmax dielectric haloscopes. | scalable haloscopes for axion dark matter detection in the 30$\\mu$ev range with rades |
the detection of a single quantum of energy with high efficiency and low false positive rate is of considerable scientific interest, from serving as single quantum sensors of optical and infra-red photons to enabling the direct detection of low-mass dark matter. we report the first experimental demonstration of magnetic avalanches induced by scattering of quanta in single-molecule magnet (smm) crystals made of mn12-acetate, establishing the use of smms as particle detectors for the first time. while the current setup has an energy threshold in the mev regime, our results motivate the exploration of a wide variety of smms whose properties could allow for detection of sub-ev energy depositions. | quantum detection using magnetic avalanches in single-molecule magnets |
in some scenarios, the dark matter particle predominantly scatters inelastically with the target, producing a heavier neutral particle in the final state. in this class of scenarios, the reach in parameter space of direct detection experiments is limited by the velocity of the dark matter particle, usually taken as the escape velocity from the milky way. on the other hand, it has been argued that a fraction of the dark matter particles in the solar system could be bound to the envelope of the local group or to the virgo supercluster, and not to our galaxy, and therefore could carry velocities larger than the escape velocity from the milky way. in this paper we estimate the enhancement in sensitivity of current direct detection experiments to inelastic dark matter scatterings with nucleons or electrons due to the non-galactic diffuse components, and we discuss the implications for some well motivated models. | enhanced prospects for direct detection of inelastic dark matter from a non-galactic diffuse component |
we chose the μ-term extended next-to-minimal supersymmetric standard model (μnmssm) for this work, and we perform a phenomenological study based on the assumption that the observed standard model (sm)-like higgs is explained by the presence of a double overlapping resonance and in light of the recent (g − 2)μ result. the study also takes into account a variety of experimental results, including dark matter (dm) direct detections and results from sparticle searches at the large hadron collider (lhc). we study the properties of dm confronted with the limits from dm direct detections. as a second step, we focus our attention on the properties of the mass-degenerate sm-like higgs bosons and on explaining the anomaly of (g −2)μ. we conclude that the anomaly of (g −2)μ can be explained in the scenario with two mass-degenerate sm-like higgs, and there are samples that meet the current constraints and fit 1 − σ anomalies of higgs data. | the mass-degenerate sm-like higgs and anomaly of (g − 2)μ in μ-term extended nmssm |
we propose hexagonal ice (h$_2$o) as a new target for light dark matter (dm) direct detection. ice, a polar material, is suitable for single phonon detection through dm scattering for which we consider light dark photon and light scalar mediator models. we report a rate sensitivity down to a dm mass of $\sim$kev, constituting a broader mass range than other promising candidates. we find better sensitivity for near-term experimental thresholds from the presence of high-frequency phonons. these advantages, and ice's availability, make it highly promising for single-phonon detection. | broad-range directional detection of light dark matter in cryogenic ice |
sabre (sodium iodide with active background rejection) is a direct detection dark matter experiment based on arrays of radio-pure nai(tl) crystals. the experiment aims at achieving an ultra-low background rate and its primary goal is to confirm or refute the results from the dama/libra experiment. the sabre proof-of-principle phase was carried out in 2020-2021 at the gran sasso national laboratory (lngs), in italy. the next phase consists of two full-scale experiments: sabre south at the stawell underground physics laboratory, in australia, and sabre north at lngs. this paper focuses on sabre south and presents a detailed simulation of the detector, which is used to characterise the background for dark matter searches including dama/libra-like modulation. we estimate an overall background of 0.72 cpd/kg/kevee in the energy range 1-6 kevee primarily due to radioactive contamination in the crystals. given this level of background and considering that the sabre south has a target mass of 50 kg, we expect to exclude (confirm) dama/libra modulation at 4 (5 )σ within 2.5 years of data taking. | simulation and background characterisation of the sabre south experiment |
for a class of macroscopic dark matter models, inelastic scattering of dark matter off a nucleus can generate electromagnetic signatures with gev-scale energy. the icecube detector, with its kilometer-scale size, is ideal for directly detecting such inelastic scattering. based on the slow particle trigger for the deepcore detector, we perform a detailed signal and background simulation to estimate the discovery potential. for order 1 gev deposited energy in each interaction, we find that icecube can probe the dark matter masses up to one gram. | icecube at the frontier of macroscopic dark matter direct detection |
pair production of higgs bosons at the large hadron collider (lhc) is known to be important for the determination of the higgs boson self-coupling and as a probe of new physics beyond the standard model (sm), especially the existence of new fundamental scalar bosons. in this paper we study in detail the pair production of higgs bosons at the lhc in a well-motivated model—the gauged two-higgs-doublet model—in which the two higgs doublets are properly embedded into a gauged s u (2 )h and a dark matter candidate emerges naturally due to the gauge symmetry. besides the deviations of the higgs couplings from the sm predictions, the existence of new scalars could significantly enhance the production cross section of higgs boson pairs at the lhc. however, when we take into account the relic density of dark matter and the null results of direct detection experiments, only a moderate enhancement can be obtained. we also comment on the capability of the lhc to distinguish the higgs pair signal due to a generic 400 gev scalar resonance in the γ γ b b ¯ final state from the sm prediction, assuming that their higgs pair production cross sections are the same. | pair production of higgs bosons at the lhc in gauged 2hdm |
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. | gev dark matter searches with the news detector |
we present a simple model of two dark matter species with opposite millicharge that can form electrically neutral bound states via the exchange of a massive dark photon. if bound state formation is suppressed at low temperatures, a sub-dominant fraction of millicharged particles remains at late times, which can give rise to interesting features in the 21 cm absorption profile at cosmic dawn. the dominant neutral component, on the other hand, can have dipole interactions with ordinary matter, leading to non-standard signals in direct detection experiments. we identify the parameter regions predicting a percent-level ionisation fraction and study constraints from laboratory searches for dark matter scattering and dark photon decays. | on dark atoms, massive dark photons and millicharged sub-components |
plasma dark matter, which arises in dissipative dark matter models, can give rise to large annual modulation signals from kev electron recoils. previous work has argued that the dama annual modulation signal could have an explanation within such a scenario. however, detailed predictions are difficult due to the inherent complexities involved in modelling the halo plasma interactions with earth-bound dark matter. here, we consider a simple phenomenological model for the dark matter velocity function relevant for direct detection experiments, and compare the resulting electron scattering rate with the new dama/libra phase 2 data. we also consider the constraints from other experiments, including xenon100 and darkside-50. | dama annual modulation from electron recoils |
in this paper, as the first part of the third step of our study on developing data analysis procedures for using 3-dimensional information offered by directional direct dark matter detection experiments in the future, we present our double-monte carlo "scattering-by-scattering" simulation of the 3-dimensional elastic wimp-nucleus scattering process, which can provide 3-d velocity information (the magnitude, the direction, and the incoming/scattering time) of each incident halo wimp as well as the recoil direction and the recoil energy of the scattered target nucleus in different celestial coordinate systems. for readers' reference, (animated) simulation plots with different wimp masses and several frequently used target nuclei for all functionable underground laboratories can be found and downloaded on our online (interactive) demonstration webpage (http://www.tir.tw/phys/hep/dm/amidas-2d/). | monte carlo scattering-by-scattering simulation of 3-dimensional elastic wimp-nucleus scattering events |
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 $\sim (10 - 100)$ mev that kinetically mixes with standard model electromagnetism at the level of $\sim 10^{-3}$ 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 mono-energetic 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 $\sim 10^{-18} - 10^{-12}$ of the galactic dark matter density for masses spanning $\sim (1 - 10^5)$ 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-nuclear bound states |
in this paper, as the second part of the third step of our study on developing data analysis procedures for using 3-dimensional information offered by directional direct dark matter detection experiments in the future, we investigate the angular distributions of the recoil direction (flux) and the recoil energy of the monte carlo simulated wimp-scattered target nuclei observed in different celestial coordinate systems. the "anisotropy" and the "directionality" ("annual" modulation) of the angular recoil-direction/energy distributions will be demonstrated. we will also discuss their dependences on the target nucleus and on the mass of incident halo wimps. for readers' reference, all simulation plots presented in this paper (and more) can be found "in animation" on our online (interactive) demonstration webpage (http://www.tir.tw/phys/hep/dm/amidas-2d/). | simulations of the angular recoil-energy distribution of wimp-scattered target nuclei for directional dark matter detection experiments |
the dama/libra observation of an annual modulation in the detection rate compatible with that expected for dark matter particles from the galactic halo has accumulated evidence for more than twenty years. it is the only hint of a direct detection of the elusive dark matter, but it is in strong tension with the negative results of other very sensitive experiments, requiring ad-hoc scenarios to reconcile all the present experimental results. testing the dama/libra result using the same target material, nai(tl), removes the dependence on the particle and halo models and is the goal of the anais-112 experiment, taking data at the canfranc underground laboratory in spain since august 2017 with 112.5 kg of nai(tl). at very low energies, the detection rate is dominated by non-bulk scintillation events and careful event selection is mandatory. this article summarizes the efforts devoted to better characterize and filter this contribution in anais-112 data using a boosted decision tree (bdt), trained for this goal with high efficiency. we report on the selection of the training populations, the procedure to determine the optimal cut on the bdt parameter, the estimate of the efficiencies for the selection of bulk scintillation in the region of interest (roi), and the evaluation of the performance of this analysis with respect to the previous filtering. the improvement achieved in background rejection in the roi, but moreover, the increase in detection efficiency, push the anais-112 sensitivity to test the dama/libra annual modulation result beyond 3σ with three-year exposure, being possible to reach 5σ by extending the data taking for a few more years than the scheduled 5 years which were due in august 2022. | improving anais-112 sensitivity to dama/libra signal with machine learning techniques |
measuring an annual modulation in a direct dark matter detection experiment is not only a proof of the existence of wimps but can also tell us more about their interaction with standard matter and maybe even their density and velocity in the halo. such a modulation has been measured by the dama/libra experiment in nai(tl) crystals. however, the interpretation as wimp signal is controversial due to contradicting results by other experiments. the sabre experiment aims to shed light on this controversy by detecting the annual modulation in the same target material as dama with twin detectors at lngs in italy and at supl in australia. the two locations in the northern and southern hemisphere allow to verify if other seasonal effects or the site have an influence on the measurement, thus reducing systematic effects. this paper will give an overview on the experimental design, the current status of the proof of principle phase mainly devoted to high-purity crystal growing, and an outlook on future plans. | sabre: wimp modulation detection in the northern and southern hemisphere |
anais (annual modulation with nal scintillators) is a dark matter direct detection experiment located at the canfranc underground laboratory (lsc), in spain. the goal is to confirm or refute in a model independent way the dama/libra positive result: an annual modulation in the low-energy detection rate compatible with the expected signal induced by dark matter particles in the galactic halo. this signal, observed for about 20 years, is in strong tension with the negative results of other very sensitive experiments, but a direct comparison using the same target material, nai(tl), was still lacking. anais-112, consisting of 112.5 kg of nai(tl) scintillators, is taking data at the lsc since august 2017. here we present the preliminary annual modulation analysis corresponding to two years of data (exposure of 220.69 kg×y) and the anais-112 projected sensitivity for the scheduled 5 y of operation. | anais-112 status: two years results on annual modulation |
this paper is the first report describing how the concentrations of silicon and boron govern the cryogenic scintillation properties of n-type gaas. it shows that valence band holes are promptly trapped on radiative centers and then combine radiatively with silicon donor band electrons at rates that increase with the density of free carriers. it also presents the range of silicon and boron concentrations needed for efficient light emission under x-ray excitation, which along with its low band gap and apparent absence of afterglow, make scintillating gaas suitable for the detection of rare, low-energy electronic excitations from interacting dark matter particles. a total of 29 samples from four different suppliers were studied. luminosities and timing responses were measured for the four principal emission bands centered at 860, 930, 1070, and 1335 nm, and for the total emissions. excitation pulses of 40 kvp x-rays were provided by a light-excited x-ray tube driven by an ultra-fast laser. scintillation emissions from 800 to 1350 nm were measured using an ingaas photomultiplier. within the concentration ranges of free carriers from 2 x 1016/cm3 to 6 x 1017/cm3 and boron from 1.5 × 1018/cm3 to 6 x 1018/cm3, nine samples have luminosities > 70 photons/kev and two have luminosities > 110 photons/kev. other samples in that range have lower luminosities due to higher concentrations of non-radiative centers. the decay times decrease by typically a factor of ten with increasing free carrier concentrations from 1017/cm3 to 2 x 1018/cm3. | how silicon and boron dopants govern the cryogenic scintillation properties of n-type gaas |
aletheia is a newly established dark matter direct detection project that aims at hunting for low-mass wimps. tpb is widely implemented in liquid helium and argon experiments to shift vuv photons to visible light. we first report that we have successfully coated ~ 3 μm tpb on the inner walls of a 10-cm cylindrical ptfe detector; we split the coating process into two steps to have all of the surfaces being coated with the same thickness; three independent methods were applied to figure out the thickness of the tpb coating layers, and consistent results were obtained. second, with an sem machine, we scanned the surface of tpb coating sample films exposed to different cryogenic temperatures. the first group of sample layers were immersed into a liquid nitrogen dewar for forty hours, the second group samples were cooled to 4.5 k for three hours, and the third group stayed at room temperature after coating. the sem-scanned images of the sample films barely show any noticeable difference. | coating μm tpb on a cylindrical detector and studying the sample films being cooled to ln and lhe temperatures |
in an extended effective operator framework, we investigate in detail the effects of light mediators on the event spectra of dark matter (dm)-nucleus scatterings. the presence of light mediators changes the interpretation of the current experimental data, especially the determination of dm particle mass. we show by analytic and numerical illustrations that in general for all the operators relevant to spin-independent scatterings, the dm particle mass allowed by a given set of experimental data increases significantly when the mediator particle becomes lighter. for instance, in the case of cdms-ii-si experiment, the allowed dm particle mass can reach ~ 50 (100) gev at 68% (90%) confidence level, which is much larger than 0~ 1 gev in the case with contact interactions. the increase of dm particle mass saturates when the mediator mass is below 𝒪(10) mev . the upper limits from other experiments such as supercdms, cdmslite, cdex, xenon10/100, lux, pandax etc. all tend to be weaker toward high dm mass regions. in a combined analysis, we show that the presence of light mediators can partially relax the tension in the current results of cdms-ii-si, supercdms and lux. | light mediators in dark matter direct detections |
previous work has argued that, in the framework of plasma dark matter models, the dama annual modulation signal can be consistently explained with electron recoils. in the specific case of mirror dark matter, that explanation requires an effective low velocity cutoff, vc ≳ 30 , 000km /s, for the halo mirror electron distribution at the detector. we show here that this cutoff can result from collisional shielding of the detector from the halo wind due to earth-bound dark matter. we also show that shielding effects can reconcile the kinetic mixing parameter value inferred from direct detection experiments with the value favoured from small scale structure considerations, ɛ ≈ 2 ×10-10. | shielding of a direct detection experiment and implications for the dama annual modulation signal |
recently it has been proposed that dark matter axions from the galactic halo can produce a small shapiro step-like signal in josephson junctions whose josephson frequency resonates with the axion mass (beck, 2013). here we show that the axion field equations in a voltage-driven josephson junction environment allow for a nontrivial solution where the axion-induced electrical current manifests itself as an oscillating supercurrent. the linear change of phase associated with this nontrivial solution implies the formal existence of a large magnetic field in a tiny surface area of the weak link region of the junction which makes incoming axions decay into microwave photons. we derive a condition for the design of josephson junction experiments so that they can act as optimum axion detectors. four independent recent experiments are discussed in this context. the observed shapiro step anomalies of all four experiments consistently point towards an axion mass of (110±2) μev. this mass value is compatible with the recent bicep2 results and implies that peccei-quinn symmetry breaking was taking place after inflation. | axion mass estimates from resonant josephson junctions |
superfluid $^4$he is a promising target material for direct detection of light ($<$ 1 gev) dark matter. possible signal channels available for readout in this medium include prompt photons, triplet excimers, and roton and phonon quasiparticles. the relative yield of these signals has implications for the sensitivity and discrimination power of a superfluid $^4$he dark matter detector. using a 16~cm$^3$ volume of 1.75~k superfluid $^4$he read out by six immersed photomultiplier tubes, we measured the scintillation from electronic recoils ranging between 36.3 and 185 kev$_\mathrm{ee}$, yielding a mean signal size of $1.25^{+0.03}_{-0.03}$~phe/kev$_\mathrm{ee}$, and nuclear recoils from 53.2 to 1090 kev$_\mathrm{nr}$. we compare the results of our relative scintillation yield measurements to an existing semiempirical model based on helium-helium and electron-helium interaction cross sections. we also study the behavior of delayed scintillation components as a function of recoil type and energy, a further avenue for signal discrimination in superfluid $^4$he. | scintillation yield from electronic and nuclear recoils in superfluid $^4$he |
the u(1)x extension of the minimal supersymmetric standard model (mssm) is called as u(1)xssm with the local gauge group su(3)c × su(2)l × u(1)y × u(1)x. u(1)xssm has three singlet higgs superfields beyond mssm. in u(1)xssm, the mass matrix of neutralino is 8 × 8, whose lightest mass eigenstate possesses cold dark matter characteristic. supposing the lightest neutralino as dark matter candidate, we study the relic density. for dark matter scattering off nucleus, the cross sections including spin-independent and spin-dependent are both researched. in our numerical results, some parameter space can satisfy the constraints from the relic density and the experiments of dark matter direct detection. | light neutralino dark matter in u(1)xssm |
we consider the classically scale invariant higgs-dilaton model of dynamical symmetry breaking extended with an extra scalar field that plays the role of dark matter. the higgs boson is light near a critical boundary between different symmetry breaking phases, where quantum corrections beyond the usual gildener-weinberg approximation become relevant. this implies a tighter connection between dark matter and higgs phenomenology. the model has only three free parameters, yet it allows for the observed relic abundance of dark matter while respecting all constraints. the direct detection cross section mediated by the higgs boson is determined by the dark matter mass alone and is testable at future experiments. | dark matter-induced multi-phase dynamical symmetry breaking |
the dark matter direct detection rates are highly correlated with the phase space distribution of dark matter particles in our galactic neighbourhood. in this paper, we make a systematic study of the impact of astrophysical uncertainties on electron recoil events at the direct detection experiments with xenon and semiconductor detectors. we find that within the standard halo model there can be up to $ \sim 50\%$ deviation from the fiducial choice in the exclusion bounds from these observational uncertainties. for non-standard halo models, we report a similar deviation from the fiducial standard halo model when fitted with recent cosmological $n$-body simulations while even larger deviations are obtained in case of the observational uncertainties. | halo uncertainties in electron recoil events at direct detection experiments |
we show that the higgsplosion mechanism makes a prediction for the mass and coupling of a wimp-like minimal scalar dark matter model. in particular the currently favoured minimal value for the higgsplosion scale, $e_\mathrm{h}\sim 25$ tev, implies a dark matter mass $m_\mathrm{dm} \sim 1.25$ tev and a moderate quartic coupling with the standard model higgs field $\lambda_\mathrm{h,dm} \sim 0.4$. this point in the parameter space is still allowed by all current experimental bounds, including direct detection (xenon), indirect detection (hess, fermi, planck) and collider searches. we have updated the scalar dark matter bounds to reflect the latest results from xenon and hess experiments. we also comment on vacuum stability and dark matter self-interactions in this model. | a higgsploding theory of dark matter |
over a handful of rotation periods, dynamical processes in barred galaxies induce nonaxisymmetric structure in dark matter halos. using n -body simulations of a milky way-like barred galaxy, we identify both a trapped dark matter component, a shadow bar, and a strong response wake in the dark matter distribution that affects the predicted dark matter detection rates for current experiments. the presence of a baryonic disk, together with well-known dynamical processes (e.g. spiral structure and bar instabilities), increases the dark matter density in the disk plane. we find that the magnitude of the combined stellar and shadow bar evolution, when isolated from the effect of the axisymmetric gravitational potential of the disk, accounts for >30 % of this overall increase in disk-plane density. this is significantly larger than that of previously claimed deviations from the standard halo model. the dark matter density and kinematic wakes driven by the milky way bar increase the detectability of dark matter overall, especially for the experiments with higher vmin . these astrophysical features increase the detection rate by more than a factor of 2 when compared to the standard halo model and by a factor of 10 for experiments with high minimum recoil energy thresholds. these same features increase (decrease) the annual modulation for low (high) minimum recoil energy experiments. we present physical arguments for why these dynamics are generic for barred galaxies such as the milky way rather than contingent on a specific galaxy model. | dynamical response of dark matter to galaxy evolution affects direct-detection experiments |
pandax-ii experiment is a dark matter direct detection experiment using about half-ton of liquid xenon as the sensitive target. the electrical pulses detected by photomultiplier tubes from scintillation photons of xenon are recorded by waveform digitizers. the data acquisition of pandax-ii relies on a trigger system that generates common trigger signals for all waveform digitizers. previously an analog device-based trigger system was used for the data acquisition system. in this paper we present a new fpga-based trigger system. the design of this system and trigger algorithms are described. the performance of this system on real data is presented. | update of the trigger system of the pandax-ii experiment |
we explore the possibility that the discrepancy in the observed anomalous magnetic moment of the muon δaμ and the predicted relic abundance of dark matter by planck data, can be explained in a lepto-philic 2-hdm augmented by a real sm singlet scalar of mass ∼ 10-80 gev. we constrain the model from the observed higgs decay width at lhc, lep searches for low mass exotic scalars and anomalous magnetic moment of an electron δae. this constrained light singlet scalar serves as a portal for the fermionic dark matter, which contributes to the required relic density of the universe. a large region of model parameter space is found to be consistent with the present observations from the direct and indirect dm detection experiments. | lepto-philic 2-hdm + singlet scalar portal induced fermionic dark matter |
in dark matter direct detection experiments, neutron is a serious source of background, which can mimic the dark matter-nucleus scattering signals. in this paper, we present an improved evaluation of the neutron background in the pandax-ii dark matter experiment by a novel approach. instead of fully relying on the monte carlo simulation, the overall neutron background is determined from the neutron-induced high energy signals in the data. in addition, the probability of producing a dark-matter-like background per neutron is evaluated with a complete monte carlo generator, where the correlated emission of neutron(s) and γ(s) in the ( α, n) reactions and spontaneous fissions is taken into consideration. with this method, the neutron backgrounds in the run 9 (26-ton-day) and run 10 (28-ton-day) data sets of pandax-ii are estimated to be (0.66±0.24) and (0.47±0.25) events, respectively. | an improved evaluation of the neutron background in the pandax-ii experiment |
within the exceptional supersymmetric standard model (e6ssm), we investigate signatures at the large hadron collider (lhc) for a long-lived charged inert higgsino, which is degenerate with the inert neutralino at tree level and a small mass splitting is generated at the loop level, resulting in a lifetime o (0.02 ) nanoseconds. we focus on the most sensitive search for long-lived charged inert higgsino decays to the lightest neutral inert higgsino dark matter and very soft charged leptons, which are eventually stopped in the detector resulting in a disappearing-track signal. furthermore, we study the displaced vertex signature of the inert chargino in the case where it is produced via the z' portal. we illustrate how difficult it is to construct displaced vertices in this class of models, though some evidence could be gained at the high luminosity lhc. finally, we compare the spin independent and spin dependent cross sections of the lightest inert higgsino dm to those of current direct detection experiments, proving that it is possible to gain sensitivity to the active dm component of this scenario in the near future. the combination of these signatures with the one emerging from z' production and decay via drell-yan, which can be characterised as belonging to the e6ssm via both the cross section and forward-backward asymmetry, could point uniquely to this non-minimal realisation of supersymmetry. | a combined approach to the analysis of space and ground experimental data within a simplified e6ssm |
this study investigates new technology for enhancing the sensitivity of low-mass dark matter detection by analyzing charge transport in a p-type germanium detector at 5.2 k. to achieve low-threshold detectors, precise calculations of the binding energies of dipole and cluster dipole states, as well as the cross sections of trapping affected by the electric field, are essential. the detector was operated in two modes: depleted at 77 k before cooling to 5.2 k and cooled directly to 5.2 k with various bias voltages. our results indicate that the second mode produces lower binding energies and suggests different charge states under varying operating modes. notably, our measurements of the dipole and cluster dipole state binding energies at zero fields were 8.716 ±0.435 mev and 6.138 ±0.308 mev, respectively. these findings have strong implications for the development of low-threshold detectors for detecting low-mass dark matter in the future. | development of low-threshold detectors for low-mass dark matter searches with a p-type germanium detector operated at cryogenic temperature |
the extension of the standard model by a real gauge singlet scalar is the simplest but the most studied model with sometimes controversial ideas on the ability of the model to address the dark matter (dm) and the electroweak phase transition (ewpt) issues simultaneously. for this model, we obtain analytically slightly different conditions for strongly first-order ewpt and apply that in computation of the dm relic density where the real scalar plays the role of the dm particle. we show that the scalar in this model before imposing the invisible higgs decay constraint, can be responsible for all or part of the dm abundance, while at the same time gives rise to a strongly first-order ewpt required for the baryogenesis. when the constraints from the direct detection experiments such as xenon100 or lux/xenon1t are considered, the model is excluded completely. | strongly first-order phase transition in real singlet scalar dark matter model |
we study the direct-detection rate for axial-vectorial dark matter scattering off nuclei in an su(2) × u(1) invariant effective theory and compare it against the lhc reach. current constraints from direct detection experiments are already bounding the mediator mass to be well into the tev range for wimp-like scenarios. this motivates a consistent and systematic exploration of the parameter space to map out possible regions where the rates could be suppressed. we do indeed find such regions and proceed to construct consistent uv models that generate the relevant effective theory. we then discuss the corresponding constraints from both collider and direct-detection experiments on the same parameter space. we find a benchmark scenario, where even for future xenonnt experiment, lhc constraints will have a greater sensitivity to the mediator mass. | z'-mediated majorana dark matter: suppressed direct-detection rate and complementarity of lhc searches |
in supersymmetric models with dirac neutrinos, the lightest sneutrino can be a good thermal dark matter candidate when the soft sneutrino trilinear parameter is large. in this paper, we focus on scenarios where the mass of the mixed sneutrino lsp is of the order of gev so the sneutrino dark matter is still viable complying with the limits by current and near future direct detection experiments. we investigate phenomenological constraints in the parameter space of the models, as well as the vacuum stability bound. finally, we show that the allowed regions can be explored by measuring higgs boson properties at future collider experiments. | phenomenological constraints on light mixed sneutrino dark matter scenarios |
despite strong evidence for the existence of large amounts of dark matter (dm) in our universe, there is no direct indication of its presence in our own solar system. all estimates of the local dm density rely on extrapolating results on much larger scales. we demonstrate for the first time the possibility of simultaneously measuring the local dm density and interaction cross section with a direct detection experiment. it relies on the assumption that incoming dm particles frequently scatter on terrestrial nuclei prior to detection, inducing an additional time-dependence of the signal. we show that for sub-gev dm, with a large spin-independent dm-proton cross section, future direct detection experiments should be able to reconstruct the local dm density with smaller than 50% uncertainty. | measuring the local dark matter density in the laboratory |
theories where a fermionic dark matter candidate interacts with the standard model through a vector mediator are often studied using minimal models, which are not necessarily anomaly-free. in fact, minimal anomaly-free simplified models are usually strongly constrained by either direct detection experiments or collider searches for dilepton resonances. in this paper, we study the phenomenology of models with a fermionic dark matter candidate that couples axially to a leptophobic vector mediator. canceling anomalies in these models requires considerably enlarging their field content. for an example minimal scenario we show that the additional fields lead to a potentially much richer phenomenology than the one predicted by the original simplified model. in particular collider searches for pair-produced neutralinos and charginos can be more sensitive than traditional monojet searches in thermally motivated parts of the parameter space where the mediator is outside the reach of current searches. | whac-a-constraint with anomaly-free dark matter models |
we analyze a model with unbroken u(1) b - l gauge symmetry where neutrino masses are generated at one loop, after spontaneous breaking of a global u(1)g symmetry. these symmetries ensure dark matter (dm) stability and the diracness of neutrinos. within this context, we examine fermionic dark matter. consistency between the required neutrino mass and the observed relic abundance indicates dark matter masses and couplings within the reach of direct detection experiments. | phenomenology of fermion dark matter as neutrino mass mediator with gauged b-l |
we study the possibility that dark radiation, sourced through the decay of dark matter in the late universe, carries electromagnetic interactions. the relativistic flux of particles induces recoil signals in direct detection and neutrino experiments through its interaction with millicharge, electric/magnetic dipole moments, or anapole moment/charge radius. taking the dm lifetime as 35 times the age of the universe, as currently cosmologically allowed, we show that direct detection (neutrino) experiments have complementary sensitivity down to ε ∼10-11 (10-12), dχ/μχ∼10-9μb (10-13μb), and aχ/bχ∼10-2 gev-2 (10-8 gev-2) on the respective couplings. finally, we show that such dark radiation can lead to a satisfactory explanation of the recently observed xenon1t excess in the electron recoil signal without being in conflict with other bounds. | terrestrial probes of electromagnetically interacting dark radiation |
we consider a simple renormalizable dark matter model consisting of two real scalars with a mass splitting δ , interacting with the sm particles through the higgs portal. we find a viable parameter space respecting all the bounds imposed by invisible higgs decay experiments at the lhc, the direct detection experiments by xenon100 and lux, and the dark matter relic abundance provided by wmap and planck. despite the singlet scalar dark matter model that is fragile against the future direct detection experiments, the scalar split model introduced here survives such forthcoming bounds. we emphasize the role of the coannihilation processes and the mixing effects in this feature. for mdm∼63 gev in this model we can explain as well the observed gamma-ray excess in the analyses of the fermi-lat data at galactic latitudes 2 ° ≤|b |≤2 0 ° and galactic longitudes |l |<2 0 ° . | scalar split wimps in future direct detection experiments |
the qcd axion is a particle postulated to exist since the 1970s to explain the strong-cp problem in particle physics. it could also account for all of the observed dark matter in the universe. the axion resonant interaction detection experiment (ariadne) intends to detect the qcd axion by sensing the fictitious 'magnetic field' created by its coupling to spin. short-range axion-mediated interactions can occur between a sample of laser-polarized 3he nuclear spins and an unpolarized source-mass sprocket. the experiment must be sensitive to magnetic fields below the 10-19 t level to achieve its design sensitivity, necessitating tight control of the experiment's magnetic environment. we describe a method for controlling three aspects of that environment which would otherwise limit the experimental sensitivity. firstly, a system of superconducting magnetic shielding is described to screen ordinary magnetic noise from the sample volume at the 108 level, which should be sufficient to reduce the contribution of johnson noise in the sprocket-shaped source mass, expected to be at the 10-12 t $/\sqrt{\mathrm{h}\mathrm{z}}$ level, to below the threshold for signal detection. secondly, a method for reducing magnetic field gradients within the sample up to 102 times is described, using a simple and cost-effective design geometry. thirdly, a novel coil design is introduced which allows the generation of fields similar to those produced by helmholtz coils in regions directly abutting superconducting boundaries. this method allows the nuclear larmor frequency of the sample to be tuned to match the axion field modulation frequency set by the sprocket rotation. finally, we experimentally investigate the magnetic shielding factor of sputtered thin-film superconducting niobium on quartz substrates for various geometries and film thicknesses relevant for the ariadne axion experiment using squid magnetometry. the methods may be generally useful for magnetic field control near superconducting boundaries in other experiments where similar considerations apply. | a method for controlling the magnetic field near a superconducting boundary in the ariadne axion experiment |
reconstructing the position of an interaction for any dual-phase time projection chamber (tpc) with the best precision is key to directly detecting dark matter. using the likelihood-free framework, a new algorithm to reconstruct the 2-d (x,y) position and the size of the charge signal (e) of an interaction is presented. the algorithm uses the secondary scintillation light distribution (s2) obtained by simulating events using a waveform generator. to deal with the computational effort required by the likelihood-free approach, we employ the bayesian optimization for likelihood-free inference (bolfi) algorithm. together with bolfi, prior distributions for the parameters of interest (x,y,e) and highly informative discrepancy measures to perform the analyses are introduced. we evaluate the quality of the proposed algorithm by a comparison against the currently existing alternative methods using a large-scale simulation study. bolfi provides a natural probabilistic uncertainty measure for the reconstruction and it improved the accuracy of the reconstruction over the next best algorithm by up to 15% when focusing on events at large radii (r > 30 cm, the outer 37% of the detector). in addition, bolfi provides the smallest uncertainties among all the tested methods. | machine learning accelerated likelihood-free event reconstruction in dark matter direct detection |
the xenon1t experiment aims for the direct detection of dark matter in a cryostat filled with 3.3 tons of liquid xenon. in order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently low. one major contributor is the $\beta$-emitter $^{85}$kr which is an intrinsic contamination of the xenon. for the xenon1t experiment a concentration of natural krypton in xenon $\rm{^{nat}}$kr/xe < 200 ppq (parts per quadrillion, 1 ppq = 10$^{-15}$ mol/mol) is required. in this work, the design of a novel cryogenic distillation column using the common mccabe-thiele approach is described. the system demonstrated a krypton reduction factor of 6.4$\cdot$10$^5$ with thermodynamic stability at process speeds above 3 kg/h. the resulting concentration of $\rm{^{nat}}$kr/xe < 26 ppq is the lowest ever achieved, almost one order of magnitude below the requirements for xenon1t and even sufficient for future dark matter experiments using liquid xenon, such as xenonnt and darwin. | removing krypton from xenon by cryogenic distillation to the ppq level |
direct detection experiments aim at the detection of dark matter in the form of weakly interacting massive particles (wimps) by searching for signals from elastic dark matter nucleus scattering. additionally, inelastic scattering in which the nucleus is excited is expected from nuclear physics and provides an additional detectable signal. in the context of a low-energy effective field theory we investigate the experimental reach to these inelastic transitions for xenon-based detectors employing a dual-phase time projection chamber. we find that once a dark matter signal is established, inelastic transitions enhance the discovery reach and we show that they allow a better determination of the underlying particle physics. | inelastic dark matter nucleus scattering |
we give a review on the simp paradigm and discuss a consistent model for simp dark mesons in the context of a dark qcd with flavor symmetry. the z'-portal interaction is introduced being compatible with stable dark mesons and is responsible for making the simp dark mesons remain in kinetic equilibrium with the sm during the freeze-out process. the simp parameter space of the z' gauge boson can be probed by future collider and direct detection experiments. | models for simp dark matter and dark photon |
we propose a simple non-supersymmetric grand unified theory (gut) based on the gauge group s o (10 ) ×u (1) ψ . the model includes 3 generations of fermions in 16 (+1 ), 10 (-2 ) and 1 (+4 ) representations. the 16 -plets contain standard model (sm) fermions plus right-handed neutrinos, and the 10 -plet and the singlet fermions are introduced to make the model anomaly-free. gauge coupling unification at mgut≃5 ×1015-1016 gev is achieved by including an intermediate pati-salam breaking at mi≃1012-1011 gev, which is a natural scale for the seesaw mechanism. for mi≃1012-1011 , proton decay will be tested by the hyper-kamiokande experiment. the extra fermions acquire their masses from u (1) ψ symmetry breaking, and a u (1) ψ higgs field drives a successful inflection-point inflation with a low hubble parameter during inflation, hinf≪mi . hence, cosmologically dangerous monopoles produced from so(10) and ps breakings are diluted away. this is the first so(10) model we are aware of in which relatively light intermediate mass (∼1010-1012 gev) primordial monopoles can be adequately suppressed. the reheating temperature after inflation can be high enough for successful leptogenesis. with the higgs field contents of our model, a z2 symmetry remains unbroken after gut symmetry breaking, and the lightest mass eigenstate among linear combinations of the 10 -plet and the singlet fermions serves as a higgs-portal dark matter (dm). we identify the parameter regions to reproduce the observed dm relic density while satisfying the current constraint from the direct dm detection experiments. the present allowed region will be fully covered by the future direct detection experiments such as lux-zeplin dm experiment. in the presence of the extra fermions, the sm higgs potential is stabilized up to mi. | inflation, proton decay, and higgs-portal dark matter in s o (10 ) ×u (1) ψ |
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