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in this work we analyse the ultimate sensitivity of dark matter direct detection experiments, the "neutrino-floor", in the presence of anomalous sources of dark radiation in form of sm or semi-sterile neutrinos. this flux-component is assumed to be produced from dark matter decay. since dark radiation may mimic dark matter signals, we perform our analysis based on likelihood statistics that allows to test the distinguishability between signals and backgrounds. we show that the neutrino floor for xenon-based experiments may be lifted in the presence of extra dark radiation. in addition, we explore the testability of neutrino dark radiation from dark matter decay in direct detection experiments. given the previous bounds from neutrino experiments, we find that xenon-based dark matter searches will not be able to probe new regions of the dark matter progenitor mass and lifetime parameter space when the decay products are sm neutrinos. in turn, if the decay instead happens to a fourth neutrino species with enhanced interactions to baryons, dr can either constitute the dominant background or a discoverable signal in direct detection experiments. | the neutrino-floor in the presence of dark radation |
the amount of energy released by a nuclear recoil ionizing the atoms of the active volume of detection appears "quenched" compared to an electron of the same kinetic energy. this different behavior in ionization between electrons and nuclei is described by the ionization quenching factor (iqf) and it plays a crucial role in direct dark matter searches. for low kinetic energies (below $50~\mathrm{kev}$), iqf measurements deviate significantly from common models used for theoretical predictions and simulations. we report measurements of the iqf for proton, an appropriate target for searches of dark matter candidates with a mass of approximately 1 gev, with kinetic energies in between $2~\mathrm{kev}$ and $13~\mathrm{kev}$ in $100~\mathrm{mbar}$ of methane. we used the comimac facility in order to produce the motion of nuclei and electrons of controlled kinetic energy in the active volume, and a news-g spc to measure the deposited energy. the comimac electrons are used as reference to calibrate the detector with 7 energy points. a detailed study of systematic effects led to the final results well fitted by $\mathrm{iqf}~(e_k)= e_k^\alpha~/~(\beta + e_k^\alpha)$ with $\alpha=0.70\pm0.08$ and $\beta = 1.32\pm0.17$. in agreement with some previous works in other gas mixtures, we measured less ionization energy than predicted from srim simulations, the difference reaching $33\%$ at $2~\mathrm{kev}$ | measurements of the ionization efficiency of protons in methane |
we experimentally investigate the effect of a magnetic field on photon detection in superconducting single-photon detectors (sspds). at low fields, the effect of a magnetic field is through the direct modification of the quasiparticle density of states of the superconductor, and magnetic field and bias current are interchangeable, as is expected for homogeneous dirty-limit superconductors. at the field where a first vortex enters the detector, the effect of the magnetic field is reduced, up until the point where the critical current of the detector starts to be determined by flux flow. from this field on, increasing the magnetic field does not alter the detection of photons anymore, whereas it does still change the rate of dark counts. this result points at an intrinsic difference in dark and photon counts, and also shows that no enhancement of the intrinsic detection efficiency of a straight sspd wire is achievable in a magnetic field. | the effect of magnetic field on the intrinsic detection efficiency of superconducting single-photon detectors |
in leptophilic scenarios, dark matter interactions with nuclei, relevant for direct detection experiments and for the capture by celestial objects, could only occur via loop-induced processes. if the mediator is a scalar or pseudo-scalar particle, which only couples to leptons, the dominant contribution to dark matter-nucleus scattering would take place via two-photon exchange with a lepton triangle loop. the corresponding diagrams have been estimated in the literature under different approximations. here, we present new analytical calculations for one-body two-loop and two-body one-loop interactions. the two-loop form factors are presented in closed analytical form in terms of generalized polylogarithms up to weight four. in both cases, we consider the exact dependence on all the involved scales, and study the dependence on the momentum transfer. we show that some previous approximations fail to correctly predict the scattering cross section by several orders of magnitude. moreover, we quantitatively show that form factors in the range of momentum transfer relevant for local galactic dark matter, can be significantly smaller than their value at zero momentum transfer, which is the approach usually considered. | two-photon exchange in leptophilic dark matter scenarios |
atom gradiometers have emerged as compelling broadband probes of scalar ultralight dark matter (uldm) candidates that oscillate with frequencies between approximately 10-2 hz and 103 hz . uldm signals with frequencies greater than ∼1 hz exceed the expected nyquist frequency of atom gradiometers, and so are affected by aliasing and related phenomena, including signal folding and spectral distortion. to facilitate the discovery of super-nyquist uldm signals, in this work we investigate the impact of these effects on parameter reconstruction using a robust likelihood-based framework. we demonstrate that accurate reconstruction of uldm parameters can be achieved as long as the experimental frequency resolution is larger than the uldm signal linewidth. notably, as uldm candidates whose frequencies differ by integer multiples of the sampling frequency are identified at the same aliased frequency, our discovery analysis recovers discrete islands in parameter space. our study represents the first comprehensive exploration of aliasing in the context of dark matter direct detection and paves the way for enhanced uldm detection strategies with atom gradiometers. | super-nyquist ultralight dark matter searches with broadband atom gradiometers |
even if the concerns related to the naturalness of the electroweak scale are repressed, the higgs mass and stability of the electroweak vacuum do not allow arbitrarily large supersymmetry breaking scale, ms, in the minimal models with split or high-scale supersymmetry. we show that ms can be raised to the grand unified theory (gut) scale if the theory below ms contains a higgs doublet, a pair of tev scale higgsino and widely separated gauginos in addition to the standard model particles. the presence of wino and gluino below o (100 ) tev leads to precision unification of the gauge couplings consistent with the current limits on the proton lifetime. wino, at this scale, renders the higgsino as pseudo-dirac dark matter which in turn evades the existing constraints from the direct detection experiments. bino mass scale is required to be ≳1010 gev to get the observed higgs mass respecting the current limit on the charged higgs mass. the framework predicts, 1 ≲tan β ≲2.2 and τ [p →e+π0]<7 ×1035 years , almost independent of values of the other parameters. the electroweak vacuum is found to be stable or metastable. the underlying framework provides an example of a viable sub-gut scale theory of supersymmetric grand unified theory in which supersymmetry and unified gauge symmetry are broken at a common scale. | precision unification and higgsino dark matter in gut scale supersymmetry |
we revisit the parameter space of singlet fermionic cold dark matter model in order to determine the role of the mixing angle between the standard model higgs and a new singlet one. furthermore, we restudy the direct detection constraints with the updated and new experimental data. as an important conclusion, this model is completely excluded by recent xenon100, pandax ii and lux data. | analyzing of singlet fermionic dark matter via the updated direct detection data |
it is well-known that dark matter (dm) direct detection experiments and the lhc are complementary, since they probe physical processes occurring at different energy scales. and yet, there are aspects of this complementarity which are still not fully understood, or exploited. for example, what is the impact that the discovery of dm at xenonnt would have on present and future searches for dm in lhc final states involving a pair of hadronic jets? in this work we investigate the impact of a xenonnt signal on the interpretation of current dijet searches at the lhc, and on the prospects for dijet signal discovery at the high-luminosity (hl) lhc in the framework of simplified models. specifically, we focus on a general class of simplified models where dm can have spin 0, 1/2 or 1, and interacts with quarks through the exchange of a scalar, pseudo-scalar, vector, or pseudo-vector mediator. we find that exclusion limits on the mediator's mass and its coupling to quarks from dijet searches at the lhc are significantly affected by a signal at xenonnt, and that o (100) signal events at xenonnt would drastically narrow the region in the parameter space of simplified models where a dijet signal can be discovered at 5 σ c.l. at the hl-lhc. | impact of a xenonnt signal on lhc dijet searches |
the theoretical interpretation of dark matter direct detection experiments is hindered by uncertainties of the microphysics governing the dark matter-nucleon interaction, and of the dark matter density and velocity distribution inside the solar system. these uncertainties are especially relevant when confronting a detection claim to the null results from other experiments, since seemingly conflicting experimental results may be reconciled when relaxing the assumptions about the form of the interaction and/or the velocity distribution. we present in this paper a halo-independent method to calculate the maximum number of events in a direct detection experiment given a set of null search results, allowing for the first time the scattering to be mediated by an arbitrary combination of various interactions (concretely we consider up to 64). we illustrate this method to examine the compatibility of the dark matter interpretation of the three events detected by the silicon detectors in the cdms-ii experiment with the null results from xenon1t and pico-60. | halo-independent comparison of direct detection experiments in the effective theory of dark matter-nucleon interactions |
cresst-ii is a direct dark matter experiment that uses scintillating calorimeters to detect wimp-induced nuclear scatter processes. heat and light signals are read out with tungsten transition edge sensors (tess) that are optimized toward their sensitivity to non-thermal phonons. the usage of superconducting thin film structures (e.g., aluminum) serving as phonon collectors to increase the collection area for this signal component is an approach to improve the sensitivity of the tes. the performance of the phonon collectors depends on the material properties and the quality achieved in the production process. we optimized the size of the phonon collectors for the given quality of cresst-ii light detectors. the diffusion lengths measured in this work are mathcal {o}(1 mm) and show a strong correlation to the residual resistivity ratio of the respective films. first tests of cresst-ii light detectors with larger as well as thicker phonon collectors individually show improvements in the measured pulse height of 30 %. | quasiparticle diffusion in cresst light detectors |
the inert doublet model is one of the simplest extensions of the standard model, providing a dark matter candidate. it is a two higgs doublet model with a discrete $z_2$ symmetry, that prevents the scalars of the second doublet (inert scalars) from coupling to the standard model fermions and makes the lightest of them stable. we study a large number of inert doublet model scenarios, which are consistent with current constraints on direct detection, including the most recent bounds from the xenon1t experiment and relic density of dark matter, as well as collider and low-energy limits. we use a set of benchmark points with different kinematic features, that promise detectable signals at future $e^+e^-$ colliders. two inert scalar pair-production processes are considered, $e^+e^- \to a~h $ and $e^+e^- \to h^+h^-$, followed by decays of $h^\pm$ and $a$ into the final states which include the lightest and stable neutral scalar dark matter candidate $h$. significance of the expected observations is studied for different benchmark models and different running scenarios, for centre-of-mass energies up to 3 tev. numerical results are presented for the signal signatures with two muons or an electron and a muon in the final state, while the qualitative conclusions can also be drawn for the semi-leptonic signatures. | inert doublet model signatures at future e+e- colliders |
the possibility of the existence of right-handed neutrinos remains one of the most important open questions in particle physics, as they can help elucidate the problems of neutrino masses, matter-antimatter asymmetry, and dark matter. interest in this topic has been increasing in recent years with the proposal of new experimental avenues by which right-handed neutrinos with masses below the electroweak scale could be detected directly using displaced-vertex signatures. at the forefront of such endeavours, the proposed ship proton beam-dump experiment is designed for a large acceptance to new weakly-coupled particles and low backgrounds. it is capable of probing right-handed neutrinos with masses below 5~gev and mixings several orders of magnitude smaller than current constraints, in regions favoured by cosmology. to probe higher masses (up to 30~gev), a promising novel approach is to identify displaced vertices from right-handed neutrinos produced in $w$ decays at lhc experiments. | right-handed neutrinos: the hunt is on! |
the directional detection of dark matter is sensitive to both recoil energy and the direction of nuclear recoil. it provides a technique whereby the local velocity distribution of dark matter may be measured. in this study, the possibility of discriminating between isotropic and anisotropic distributions is investigated through numerical simulations with a directional detector. the numerical simulation is performed for two cases. these cases are classified according to detectors as follows: one corresponds to an angular histogram distribution of the signals whereas the other corresponds to an energy-angular distribution of the signals. in order to discriminate the energy-angular distributions, a chi-squared test between ideal data set and experimental data and likelihood estimation are proposed. the anisotropy of the velocity distribution was shown to be discriminated at 90% confidence level if o(104) signals are obtained for both gaseous detector and solid detector. especially, the analysis for the solid detector case and comparison with the gaseous detector case are discussed for the first time. | discrimination of anisotropy in dark matter velocity distribution with directional detectors |
we study natural supersymmetry in the generalized minimal supergravity (gmsugra). for the parameter space with low energy, electroweak fine-tuning measures less than 50, we are left with only the z -pole, higgs-pole, and higgsino lsp scenarios for dark matter (dm). we perform the focused scans for such parameter space and find that it satisfies various phenomenological constraints and is compatible with the current direct detection bound on neutralino dm reported by the lux experiment. such parameter space also has solutions with correct dm relic density besides the solutions with dm relic density smaller or larger than 5 σ wmap9 bounds. we present five benchmark points as examples. in these benchmark points, the gluino and the first two generations of squarks are heavier than 2 tev, stop t∼1 ,2 are in the mass range [1, 2] tev, while sleptons are lighter than 1 tev. some part of the parameter space can explain the muon anomalous magnetic moment within 3 σ as well. we also perform the collider study of such solutions by implementing and comparing with relevant studies done by the atlas and cms collaborations. we find that the points with higgsino dominant χ∼20/χ∼1± mass up to 300 gev are excluded in z -pole scenario while for higgs-pole scenario, the points with χ∼20 mass up to 460 gev are excluded. we also notice that the higgsino lsp points in our present scans are beyond the reach of present lhc searches. next, we show that for both the z -pole and higgs-pole scenarios, the points with electroweak fine-tuning measures around 20 do still survive. | status of natural supersymmetry from the generalized minimal supergravity in light of the current lhc run-2 and lux data |
guided by gauge principles we discuss a predictive and falsifiable uv complete model where the dirac fermion that accounts for the cold dark matter abundance in our universe induces the lepton flavor violation (lfv) decays μ →e γ and μ →e e e as well as μ -e conversion. we explore the interplay between direct dark matter detection, relic density, collider probes and lepton flavor violation to conclusively show that one may have a viable dark matter candidate yielding flavor violation signatures that can be probed in the upcoming experiments. in fact, keeping the dark matter mass at the tev scale, a sizable lfv signal is possible, while reproducing the correct dark matter relic density and meeting limits from direct-detection experiments. | lepton flavor violation induced by dark matter |
the dark matter velocity distribution in the solar neighbourhood is an important astrophysical input which enters in the predicted event rate of dark matter direct detection experiments. it has been recently suggested that the local dark matter velocity distribution can be inferred from that of old or metal-poor stars in the milky way. we investigate this potential relation using six high resolution magneto-hydrodynamical simulations of milky way-like galaxies of the auriga project. we do not find any correlation between the velocity distributions of dark matter and old stars in the solar neighbourhood. likewise, there are no strong correlations between the local velocity distributions of dark matter and metal-poor stars selected by applying reasonable cuts on metallicity. in some simulated galaxies, extremely metal-poor stars have a velocity distribution that is statistically consistent with that of the dark matter, but the sample of such stars is so small that we cannot draw any strong conclusions. | on the correlation between the local dark matter and stellar velocities |
we use cosmological hydrodynamic zoom-in simulations to study early structure formation in two dark matter (dm) cosmologies, the standard cold dark matter (cdm) model, and a thermal warm dm (wdm) model with a particle mass of mχc2 = 3 kev. we focus on dm haloes with virial masses m ∼ 1010 m⊙. we find that the first star formation activity is delayed by ∼200 myr in the wdm model, with similar delays for metal enrichment and the formation of the second generation of stars. however, the differences between the two models in globally averaged properties, such as star formation rate density and mean metallicity, decrease towards lower redshifts (z ≲ 10). metal enrichment in the wdm cosmology is restricted to dense environments, while low-density gas can also be significantly enriched in the cdm case. the free-free contribution from early structure formation at redshifts z > 6 to the cosmic radio background (crb) is 3_{-1.5}^{+13} ( 8_{-3.5}^{+33}) per cent of the total signal inferred from radio experiments such as arcade 2, in the wdm (cdm) model. the direct detection of the h2 emission from early structure formation (z ≳ 7.2), originating from the low-mass haloes explored here, will be challenging even with the next generation of far-infrared space telescopes, unless the signal is magnified by at least a factor of 10 via gravitational lensing or shocks. however, more massive haloes with m ≳ 1012 m⊙ may be observable for z ≳ 10, even without magnification, provided that our extrapolation from the scale of our simulated haloes is valid. | global radiation signature from early structure formation |
we develop the phenomenology of scenarios in which a dark matter candidate interacts with a top quark through flavour-changing couplings, employing a simplified dark matter model with an s-channel vector-like mediator. we study in detail the top-charm flavour-changing interaction, by investigating the single top plus large missing energy signature at the lhc as well as constraints from the relic density and direct and indirect dark matter detection experiments. we present strategies to distinguish between the top-charm and top-up flavour-changing models by taking advantage of the lepton charge asymmetry as well as by using charm-tagging techniques on an extra jet. we also show the complementarity between the lhc and canonical dark matter experiments in exploring the viable parameter space of the models. | signatures of top flavour-changing dark matter |
we reexamine a renormalizable model of a fermionic dark matter with a gauge singlet dirac fermion and a real singlet scalar which can ameliorate the scalar mass hierarchy problem of the standard model (sm). our model setup is the minimal extension of the sm for which a realistic dark matter (dm) candidate is provided and the cancellation of one-loop quadratic divergence to the scalar masses can be achieved by the veltman condition (vc) simultaneously. this model extension, although renormalizable, can be considered as an effective low-energy theory valid up to cut-off energies about 10 tev. we calculate the one-loop quadratic divergence contributions of the new scalar and fermionic dm singlets, and constrain the model parameters using the vc and the perturbative unitarity conditions. taking into account the invisible higgs decay measurement, we show the allowed region of new physics parameters satisfying the recent measurement of relic abundance. with the obtained parameter set, we predict the elastic scattering cross section of the new singlet fermion into target nuclei for a direct detection of the dark matter. we also perform the full analysis with arbitrary set of parameters without the vc as a comparison, and discuss the implication of the constraints by the vc in detail. | singlet fermionic dark matter with veltman conditions |
we report the measurement of muons and muon-induced phosphorescence in dm-ice17, a nai(tl) direct detection dark matter experiment at the south pole. muon interactions in the crystal are identified by their observed pulse shape and large energy depositions. the measured muon rate in dm-ice17 is 2.93 ±0.04 μ /crystal/day with a modulation amplitude of 12.3 ±1.7 % , consistent with expectation. following muon interactions, we observe long-lived phosphorescence in the nai(tl) crystals with a decay time of 5.5 ±0.5 s . the prompt energy deposited by a muon is correlated to the amount of delayed phosphorescence, the brightest of which consist of tens of millions of photons. these photons are distributed over tens of seconds with a rate and arrival timing that do not mimic a scintillation signal above 2 kevee . while the properties of phosphorescence vary among individual crystals, the annually modulating signal observed by dama cannot be accounted for by phosphorescence with the characteristics observed in dm-ice17. | measurement of muon annual modulation and muon-induced phosphorescence in nai(tl) crystals with dm-ice17 |
direction sensitivity could provide robust evidence for the direct detection of weakly interacting massive particles constituting dark matter. however, the sensitivity of this method remains low due to the radioactive backgrounds. the purpose of this study is to develop a low-background detector as a two-dimensional imaging device for a gaseous time projection chamber. in direction-sensitive dark matter experiments (e.g. newage), α-rays emitted from the detector components often create substantial radioactive backgrounds. based on the study of the background of newage, a new detector "low- α μ-pic" is developed. the produced μ-pic performs well as a gas detector and the α-ray emission rate from the μ-pic reduced by a factor of 100. | development of a low- α-emitting μ-pic as a readout device for direction-sensitive dark matter detectors |
we consider a neutrino two higgs doublet model ( νthdm) in which neutrinos obtain naturally small dirac masses from the soft symmetry breaking of a global u(1) xsymmetry. we extended the model so the soft term is generated by the spontaneous breaking of u(1) xby a new scalar field. the symmetry breaking pattern can also stabilize a scalar dark matter candidate. after constructing the model, we study the phenomenology of the dark matter: relic density, direct and indirect detection. | scalar dark matter search from the extended νthdm |
studies of dark matter models lie at the interface of astrophysics, cosmology, nuclear physics and collider physics. constraining such models entails the capability to compare their predictions to a wide range of observations. in this review, we present the impact of global constraints to a specific class of models, called dark matter simplified models. these models have been adopted in the context of collider studies to classify the possible signatures due to dark matter production, with a reduced number of free parameters. we classify the models that have been analysed so far and for each of them we review in detail the complementarity of relic density, direct and indirect searches with respect to the lhc searches. we also discuss the capabilities of each type of search to identify regions where individual approaches to dark matter detection are the most relevant to constrain the model parameter space. finally we provide a critical overview on the validity of the dark matter simplified models and discuss the caveats for the interpretation of the experimental results extracted for these models. | impact of cosmological and astrophysical constraints on dark matter simplified models |
we study the prospect of dark matter (dm) searches in the monojet channel at future p p colliders with center-of-mass energies of 33, 50, and 100 tev. we consider a class of simplified models in which a vector boson connecting dm particles to quarks is introduced. comparing with studies in the effective field theory, the present framework gives more reasonable production rates and kinematics of the dm signatures. we estimate the sensitivities of future colliders with an integrated luminosity of 3 ab-1 to the dm-induced monojet signature and show the parameter space that can be explored. the constraints from direct and indirect dm detection experiments are compared with the future collider sensitivities. we find that the future collider detection will be much more sensitive than the indirect detection for the vector interaction and have better sensitivities than those of the direct detection by several orders of magnitude for the axial vector interaction. | searches for dark matter signals in simplified models at future hadron colliders |
we propose a u (1 )' model inspired by e6, which has an isospin-violation dark matter. with extra an two pairs of vectorlike quarks, we can assign the proper u (1 )' charges for the first two-generation quark doublets and explain why the first two-generation quarks are lighter than the third generation. by choosing a proper linear combination of two extra u (1 ) gauge symmetries in e6, it is natural to realize the ratio fn/fp=-0.7 so as to maximally relax the constraints from the xenon based direct detection experiments. we study the sensitivities of the dark matter direct and indirect detection experiments and identify the parameter spaces that can give the observed relic density. we also study the sensitivities of the future colliders with a center mass energy √{s }=33 /50 /100 tev and compare the different detection methods. we show that in some parameter spaces, the future colliders can give much stronger limits. | isospin-violating dark matter in a u (1 )' model inspired by e6 |
we report on a first measurement with a sensitive opto-mechanical force sensor designed for the direct detection of coupling of real chameleons to matter. these dark energy candidates could be produced in the sun and stream unimpeded to earth. the kwisp detector installed on the cast axion search experiment at cern looks for tiny displacements of a thin membrane caused by the mechanical effect of solar chameleons. the displacements are detected by a michelson interferometer with a homodyne readout scheme. the sensor benefits from the focusing action of the abrixas x-ray telescope installed at cast, which increases the chameleon flux on the membrane. a mechanical chopper placed between the telescope output and the detector modulates the incoming chameleon stream. we present the results of the solar chameleon measurements taken at cast in july 2017, setting an upper bound on the force acting on the membrane of 80 pn at 95% confidence level. the detector is sensitive for direct coupling to matter 104 ≤βm ≤ 108 , where the coupling to photons is locally bound to βγ ≤ 1011 . | first results on the search for chameleons with the kwisp detector at cast |
we propose to use the defect creation energy loss in commonly used high energy physics solid state detectors as a tool to statistically identify dark matter signal from background. we simulate the energy loss in the process of defect creation using density functional theory and molecular dynamics methods and calculate the corresponding expected dark matter spectra. we show that in phonon-mediated solid state detectors, the energy loss due to defect creation convolved with the expected dark matter interaction signal results in a significant change in the expected spectra for common detector materials. with recent progress towards $\sim$10 ev threshold low-mass dark matter searches, this variation in expected dark matter spectrum can be used as a direct signature of dark matter interactions with atomic nuclei. | crystal defects: a portal to dark matter detection |
the asteroseismic modelling of solar-like stars has proved to be valuable in constraining dark matter. in this work, we study for the first time the influence of asymmetric dark matter (adm) in the evolution of a subgiant star (kic 8228742) by direct comparison with observational data. both spectroscopic and seismic data are analysed with a new approach to the stellar calibration method, in which dm properties can also be considered as free inputs. in another phase of this study, a calibrated standard stellar model (without dm) is used as the benchmark for dm models. we find that the latter models consistently outperform the former for 10-40 ≤ σsd < 10-38 cm2, hinting that the presence of adm in stars of this type does not go against observations. moreover, we show that stellar seismology allows us to suggest exclusion limits that complement the constraints set by direct detection experiments. different seismic observables are proposed to study dm properties and δπℓ is found to be the most reliable, having the potential to build future dm exclusion diagrams. this new methodology can be a powerful tool in the analysis of the data coming from the next generation of asteroseismic missions. | on asymmetric dark matter constraints from the asteroseismology of a subgiant star |
the global network of optical magnetometers for exotic physics searches (gnome) conducts an experimental search for certain forms of dark matter based on their spatiotemporal signatures imprinted on a global array of synchronized atomic magnetometers. the experiment described here looks for a gradient coupling of axion-like particles (alps) with proton spins as a signature of locally dense dark matter objects such as domain walls. in this work, stochastic optimization with machine learning is proposed for use in a search for alp domain walls based on gnome data. the validity and reliability of this method were verified using binary classification. the projected sensitivity of this new analysis method for alp domain-wall crossing events is presented. | a machine learning algorithm for direct detection of axion-like particle domain walls |
liquid argon is used as a target material in several current and planned experiments related to dark matter direct searching and neutrino detection. sipm is becoming the standard for scintillator detectors because of its advantages over traditional pmt. in this paper, we developed a single-phase liquid argon detector with sipm readout and evaluated its light yield with an 241am γ source. after eliminating the effect of sipm cross-talks and after-pulses, we achieve the light yield of 12.5 ± 3.4 photoelectrons per kevee primarily generated by the argon scintillation, which is one of the best results for a liquid argon detector. in addition, we provide an experimental method to estimate the effect of cross-talks and after-pulses on light yield using dark noise data. finally, we quantitatively give the relationship between the light yield and the decay time of the slow component of a liquid argon detector. | developing a single-phase liquid argon detector with sipm readout |
we propose a vector dark matter model with an exotic dark su(2) gauge group. two higgs triplets are introduced to spontaneously break the symmetry. all of the dark gauge bosons become massive, and the lightest one is a viable vector dm candidate. its stability is guaranteed by a remaining z2 symmetry. we study the parameter space constrained by the higgs measurement data, the dark matter relic density, and direct and indirect detection experiments. we find numerous parameter points satisfying all the constraints, and they could be further tested in future experiments. similar methodology can be used to construct vector dark matter models from an arbitrary so(n) gauge group. | vector dark matter from split su(2) gauge bosons |
we consider the prospects for multiple dark matter direct detection experiments to determine if the interactions of a dark matter candidate are isospin-violating. we focus on theoretically well-motivated examples of isospin-violating dark matter (ivdm), including models in which dark matter interactions with nuclei are mediated by a dark photon, a z , or a squark. we determine that the best prospects for distinguishing ivdm from the isospin-invariant scenario arise in the cases of dark photon-or z -mediated interactions, and that the ideal experimental scenario would consist of large exposure xenon- and neon-based detectors. if such models just evade current direct detection limits, then one could distinguish such models from the standard isospin-invariant case with two detectors with of order 100 ton-year exposure. | directly detecting isospin-violating dark matter |
protection from and rejection of backgrounds is a key issue for the edelweiss-iii direct dark matter detection experiment which aims at exploring the 10-9 pb cross-section region for spin-independent wimp-nucleon interaction. the detector is located in the low radioactivity environment of the modane underground laboratory and consists of 36 advanced fid germanium detectors operating at 18 mk in a dilution refrigerator in order to identify eventual rare nuclear recoils induced by elastic scattering of wimps from our galactic halo. i will discuss the background and the methods of rejecting it with the fid detectors. detector performances and the first analysis of data acquired in a long-term campaign will be presented as well. the fid detector technology is not limited to edelweiss-iii but can further be employed in the next generation of cryogenic detector experiments. | background investigation in edelweiss-iii |
a degenerate sfermionic particle spectrum can escape constraints from flavor physics, and at the same time evade the limits from the direct searches if the degeneracy extends to the gaugino-higgsino sector. inspired by this, we consider a scenario where all the soft terms have an approximately common mass scale at msusy , with splittings ≲o (10 %). as a result, the third generation sfermions have large to maximal (left-right) mixing, the same being the case with charginos and some sectors of the neutralino mass matrix. we study this scenario in the light of discovery of the higgs boson with mass ∼125 gev . we consider constraints from b physics, the anomalous magnetic moment of the muon and the dark matter relic density. we find that a supersymmetric spectrum as light as 600 gev could be consistent with all current data and also account for the observed anomalous magnetic moment of the muon within 2 σ . the neutralino relic density is generally too small to saturate the measured cold dark matter relic density. direct detection limits from xenon100 and lux put severe constraints on this scenario which will be conclusively probed by the xenonnt experiment. | indirect searches of the degenerate mssm |
standard model (sm) spin-zero singlets are constrained through their di-bosonic decay channels via an effective coupling induced by a vector-like quark (vlq) loop at the lhc for √{s}=13 tev. these spin-zero resonances are then considered as portals for scalar, vector or fermionic dark matter particle interactions with sm gauge bosons. we find that the model is validated with respect to the observations from lhc data and from cosmology, indirect and direct detection experiments for an appreciable range of scalar, vector and fermionic dm masses greater than 300 gev and vlq masses ≥ 400 gev, corresponding to the three choice of portal masses 270 gev, 500 gev and 750 gev respectively. | spin-0± portal induced dark matter |
we discuss an in-situ evaluation of the 85kr, 222rn, and 220rn background in pandax-i, a 120-kg liquid xenon dark matter direct detection experiment. combining with a simulation, their contributions to the low energy electron-recoil background in the dark matter search region are obtained. | krypton and radon background in the pandax-i dark matter experiment |
we investigate a simple setup in which an excess in the di-photon invariant mass distribution around 750 gev, as seen by the atlas and cms collaborations, is originated through a pair of collimated photon pairs. in this framework a scalar state s decays into two light pseudo-goldstone bosons a, each of which subsequently decays into a pair of collimated photons which are misidentified as a single photon. in a minimal context of spontaneous symmetry breaking, we show that coupling a complex scalar field φ=(s+ia)/√2 to a fermionic dark matter candidate χ, also responsible for generating its mass, allows for the correct relic density in a large region of the parameter space, while not being excluded by the direct or indirect detection experiments. moreover, the correct relic abundance can naturally co-exist with a relatively large width for the resonant field s. | re-opening dark matter windows compatible with a diphoton excess |
we describe two natural scenarios in which both dark matter wimps (weakly interacting massive particles) and a variety of supersymmetric partners should be discovered in the foreseeable future. in the first scenario, the wimps are neutralinos, but they are only one component of the dark matter, which is dominantly composed of other relic particles such as axions. (this is the multicomponent model of baer, barger, sengupta, and tata.) in the second scenario, the wimps result from an extended higgs sector and may be the only dark matter component. in either scenario, both the dark matter wimp and a plethora of other neutral and charged particles await discovery at many experimental facilities. the new particles in the second scenario have far weaker cross-sections for direct and indirect detection via their gauge interactions, which are either momentum-dependent or second-order. however, as we point out here, they should have much stronger interactions via the higgs. we estimate that their interactions with fermions will then be comparable to (although not equal to) those of neutralinos with a corresponding higgs interaction. it follows that these newly proposed dark matter particles should be within reach of emerging and proposed facilities for direct, indirect, and collider-based detection. | two natural scenarios for dark matter particles coexisting with supersymmetry |
in the two-component majorana dark matter model, one dark matter particle can scatter off the target nuclei, and turn into a slightly heavier component. in the framework of a simplified model with a vector boson mediator, both the tree-level and loop-level processes contribute to the signal in direct detection experiment. in this paper, we report the search results for such dark matter from pandax-ii experiment, using total data of the full 100.7 tonne⋅day exposure. no significant excess is observed, so strong constraints on the combined parameter space of mediator mass and dark matter mass are derived. with the complementary search results from collider experiments, a large range of parameter space can be excluded. | a search for two-component majorana dark matter in a simplified model using the full exposure data of pandax-ii experiment |
dark matter with mev scale mass is difficult to detect with standard direct search detectors. however, they can be searched for by considering the up-scattering of kinetic energies by cosmic rays. because the dark matter density is higher in the central region of the galaxy, the up-scattered dark matter will arrive at earth from the direction of the galactic center. once the dark matter is detected, we can expect to recognize this feature by directional direct detection experiments. in this study, we simulate the nuclear recoils of the up-scattered dark matter and quantitatively reveal that a large amount of this type of dark matter is arriving from the direction of the galactic center. also, we have shown that the characteristic signatures of the up-scattered dark matter can be verified with more than 5σ confidence levels for the assumed target atoms and future upgrades to directional detectors. | directional direct detection of light dark matter up-scattered by cosmic rays from direction of the galactic center |
in this work, we consider an extension of the standard model (sm) with an inert higgs doublet and a real scalar singlet, in order to address problems around the origin of dark matter (dm). in this model, the lightest among the cp-odd and cp-even neutral inert components plays the role of a dm candidate, where the model parameters are subject to many theoretical and experimental constraints. these constraints include vacuum stability, perturbativity, lep negative searches, electroweak precision tests, higgs di-photon, higgs invisible and higgs undetermined decays, dm relic density and dm direct detection bounds. using these constraints, we find that the allowed parameter space for these models is quite sizeable and could be explored in upcoming collider and astrophysical searches. | dark matter in a singlet extended inert higgs doublet model |
assuming for weakly interacting massive particles (wimps) a maxwellian velocity distribution in the galaxy we provide an assessment of the sensitivity of existing dark matter (dm) direct detection (dd) experiments to operators up to dimension 7 of the relativistic effective field theory describing dark matter interactions with quarks and gluons. in particular we focus on a systematic approach, including an extensive set of experiments and large number of couplings, both exceeding for completeness similar analyses in the literature. the relativistic effective theory requires to fix one coupling for each quark flavor, so in principle for each different combination the bounds should be recalculated starting from direct detection experimental data. to address this problem we propose an approximate model-independent procedure that allows to directly calculate the bounds for any combination of couplings in terms of model-independent limits on the wilson coefficients of the non-relativistic theory expressed in terms of the wimp mass and of the neutron-to-proton coupling ratio cn/cp. we test the result of the approximate procedure against that of a full calculation, and discuss its possible pitfalls and limitations. we also provide a simple interpolating interface in python that allows to apply our method quantitatively. | on the sensitivity of present direct detection experiments to wimp-quark and wimp-gluon effective interactions: a systematic assessment and new model-independent approaches |
the paper presents a novel approach to the description of the nonrelativistic weak interaction of a massive neutral particle (lepton) and a nucleus, in which the latter retains its integrity. the cross section of such a process is a sum of the elastic (or coherent) contribution, when the nucleus remains in its original state, and the inelastic (incoherent) contribution, when the nucleus is in an excited state. smooth transition from elastic scattering to inelastic scattering is governed by the dependence of the nuclear form factors on the momentum transferred to the nucleus. the intensity of the weak interaction is set by the parameters that determine the contributions to the probability amplitude from the scalar products of the leptonic and nucleon currents. the resulting expressions are of interest, at least in the problem of direct detection of neutral massive weakly interacting particles of dark matter, since in this case, in contrast to the generally accepted approach, both elastic and inelastic processes are simultaneously considered. it is shown that the presence of the inelastic contribution accompanied by emission of characteristic radiation (photons) from the deexcitation of the nucleus turns out to be decisive when the coherent cross section is strongly suppressed or cannot be detected. the former takes place if the corresponding interaction constant is close to zero or if the momentum transferred to the nucleus is too great and the coherence condition is not met. when the measurable recoil energy of the nucleus is below the detection threshold, the coherent cross section cannot be seen at all. in this situation, "inelastic" photons are the only detectable signal of the interaction between dark matter particles and matter. therefore in order to extract maximum information about dark matter particles, one should plan experiments aimed at the direct detection of dark matter particles in a setting that allows one to detect both the recoil energy of the nucleus and the gamma quanta from the deexcitation of the nucleus | coherence in scattering of massive weakly interacting neutral particles of nuclei |
we investigate the possibility of detecting the 3d cross correlation power spectrum of the ly-α forest and hi 21 cm signal from the post reionization epoch. {the cross-correlation signal is directly dependent on the dark matter power spectrum and is sensitive to the 21-cm brightness temperature and ly-α forest biases. these bias parameters dictate the strength of anisotropy in redshift space.} we find that the cross-correlation power spectrum can be detected using 400 hrs observation with ska-mid (phase 1) and a futuristic boss like experiment with a quasar (qso) density of 30 deg-2 at a peak snr of 15 for a single field experiment at redshift z = 2.5. on large scales using the linear bias model. we also study the possibility of constraining various bias parameters using the cross power spectrum. we find that with the same experiment 1 σ {conditional errors} on the 21-cm linear redshift space distortion parameter βt and βf corresponding to the ly-α forest are ~ 2.7 % and ~ 1.4 % respectively for 01 independent pointings of the ska-mid (phase 1). this prediction indicates a significant improvement over existing measurements. we claim that the detection of the 3d cross correlation power spectrum will not only ascertain the cosmological origin of the signal in presence of astrophysical foregrounds but will also provide stringent constraints on large scale hi biases. this provides an independent probe towards understanding cosmological structure formation. | on using large scale correlation of the ly-α forest and redshifted 21-cm signal to probe hi distribution during the post reionization era |
the complex scalar dark matter (dm) candidate in the gauged two-higgs-doublet model, stabilized by a peculiar hidden parity (h parity), is studied in detail. we explore the parameter space for the dm candidate by taking into account the most recent dm constraints from various experiments, in particular, the planck relic density measurement and the current dm direct detection limit from xenon1t. we separate our analysis in three possible compositions for the mixing of the complex scalar. we first constrain our parameter space with the vacuum stability and perturbative unitarity conditions for the scalar potential, lhc higgs measurements, plus drell-yan and electroweak precision test constraints on the gauge sector. we find that dm dominated by composition of the inert doublet scalar is completely excluded by further combining the previous constraints with both the latest results from planck and xenon1t. we also demonstrate that the remaining parameter space with two other dm compositions can be further tested by indirect detection like the future cherenkov telescope array gamma-ray telescope. | complex scalar dark matter in the gauged two-higgs-doublet model |
cosine-100, a direct detection wimp dark matter search, is using 106 kg of nai(tl) crystals to definitively test the dama collaboration’s claim of wimp discovery. in the context of most standard models of wimp dark matter, the dama result is in conflict with other direct detection experiments. to resolve this tension, cosine-100 seeks to independently test the dama observation using a detector of the same target material as dama, thus definitively confirming or refuting their claim of wimp discovery. here, we present the current status and projected sensitivity of cosine-100, along with the projected sensitivity of cosine-200, a possible next phase of the experiment. | current status and projected sensitivity of cosine-100 |
we investigate the presence and importance of dark matter discs in a sample of 24 simulated milky way galaxies in the apostle project, part of the eagle programme of hydrodynamic simulations in λcdm cosmology. it has been suggested that a dark disc in the milky way may boost the dark matter density and modify the velocity modulus relative to a smooth halo at the position of the sun, with ramifications for direct detection experiments. from a kinematic decomposition of the dark matter and a real space analysis of all 24 haloes, we find that only one of the simulated milky way analogues has a detectable dark disc component. this unique event was caused by a merger at late time with an lmc-mass satellite at very low grazing angle. considering that even this rare scenario only enhances the dark matter density at the solar radius by 35 per cent and affects the high-energy tail of the dark matter velocity distribution by less than 1 per cent, we conclude that the presence of a dark disc in the milky way is unlikely, and is very unlikely to have a significant effect on direct detection experiments. | the low abundance and insignificance of dark discs in simulated milky way galaxies |
for a wide range of models, dark matter can interact with qcd gluons via chromo-rayleigh interactions. we point out that the large hadron collider (lhc), as a gluon machine, provides a superb probe of such interactions. in this paper, we introduce simplified models to uv-complete two effective dark matter chromo-rayleigh interactions and identify the corresponding collider signatures, including four jets or a pair of di-jet resonances plus missing transverse energy. after performing collider studies for both the 8 tev and 14 tev lhc, we find that the lhc can be more sensitive to dark matter chromo-rayleigh interactions than direct detection experiments and thus provides the best opportunity for future discovery of this class of models. | chromo-rayleigh interactions of dark matter |
we investigate a model with two real scalar fields that minimally generates exponentially different scales in an analog of the coleman-weinberg mechanism. the classical scale invariance -- the absence of dimensionful parameters in the tree-level action, required in such a scale generation -- can naturally be understood as a special case of the multipoint criticality principle. this two-scalar model can couple to the standard model higgs field to realize a maximum multiplicity of criticality for field values around the electroweak scale, providing a generalization of the classical scale invariance to a wider class of criticality. as a bonus, one of the two scalars can be identified as higgs-portal dark matter. we find that this model can be consistent with the constraints from dark matter relic abundance, its direct detection experiments, and the latest lhc data, while keeping the perturbativity up to the planck scale. we then present successful benchmark points satisfying all these constraints: the mass of dark matter is a few tev, and its scattering cross section with nuclei is of the order of $10^{-9}$ pb, reachable in near future experiments. the mass of extra higgs boson $h$ is smaller than or of the order of 100 gev, and the cross section of $e^+e^- \to zh$ can be of fb level for collision energy 250 gev, targetted at future lepton colliders. | dark matter in minimal dimensional transmutation with multicritical-point principle |
the large hadron electron collider (lhec) has been designed to push the field of deep inelastic scattering to the high energy and intensity frontier using an intense electron beam with a proton beam from the high luminosity-large hadron collider. however, lhec is also a great laboratory for new physics. in this work, we propose a search for dark matter that couples with leptons. this may yield ${ej}+{/}\!\!\!\!{e}$ and $\mu j+{/}\!\!\!\!{e}$ signals that can be potentially observed through simple missing-energy cuts that suppress the standard model background. considering direct dark matter detection and lhc constraints, we show that lhec offers a complementary probe for a weak scale dark matter fermion for masses up to 350 gev, which reproduces the correct relic density, and has interesting implications for lepton flavor violation. | search for leptophilic dark matter at the lhec |
paleo-detectors are a proposed experimental technique to search for dark matter (dm). in lieu of the conventional approach of operating a tonne-scale real-time detector to search for dm-induced nuclear recoils, paleo-detectors take advantage of small samples of naturally occurring rocks on earth that have been deep underground ($\gtrsim 5$ km), accumulating nuclear damage tracks from recoiling nuclei for $\mathcal{o}(1)$ gyr. modern microscopy techniques promise the capability to read out nuclear damage tracks with nanometer resolution in macroscopic samples. thanks to their $\mathcal{o}(1)$ gyr integration times, paleo-detectors could constitute nuclear recoil detectors with kev recoil energy thresholds and 100 kilotonne-yr exposures. this combination would allow paleo-detectors to probe dm-nucleon cross sections orders of magnitude below existing upper limits from conventional direct detection experiments. in this article, we use improved background modeling and a new spectral analysis technique to update the sensitivity forecast for paleo-detectors. we demonstrate the robustness of the sensitivity forecast to the (lack of) ancillary measurements of the age of the samples and the parameters controlling the backgrounds, systematic mismodeling of the spectral shape of the backgrounds, and the radiopurity of the mineral samples. specifically, we demonstrate that even if the uranium concentration in paleo-detector samples is $10^{-8}$ (per weight), many orders of magnitude larger than what we expect in the most radiopure samples obtained from ultra basic rock or marine evaporite deposits, paleo-detectors could still probe dm-nucleon cross sections below current limits. for dm masses $\lesssim 10$ gev/$c^2$, the sensitivity of paleo-detectors could still reach down all the way to the conventional neutrino floor in a xe-based direct detection experiment. | new projections for dark matter searches with paleo-detectors |
the high scintillation luminosity of n-type gaas at 10 °k is surprising because (1) with a refractive index of 3.5, escape is inhibited by total internal reflection and (2) narrow-beam experiments at 90 °k report infrared absorption coefficients of several per cm. this paper presents monte carlo calculations showing that the high luminosity at 10 °k can be explained if (1) the narrow-beam absorption is almost all optical scattering and (2) the absolute absorption coefficient is below 0.1 per cm. sixteen surface reflector configurations are simulated for a range of internal scattering and absolute absorption coefficients, and these can guide the design of cryogenic scintillating gaas targets for the direct detection of dark matter. the discussion section presents a possible infrared scattering mechanism based on the metallic nature of n-type gaas. a supplement file describes (1) the monte carlo program steps in detail and (2) how narrow-beam and integrating sphere experiments can measure the cryogenic optical scattering and absolute absorption coefficients. | monte carlo calculations of the extraction of scintillation light from cryogenic n-type gaas |
we consider an extension of the lepto-specific 2hdm with an extra singlet s as a dark matter candidate. taking into account theoretical and experimental constraints, we investigate the possibility to address both the γ-ray excess detected at the galactic centre and the discrepancy between the standard model prediction and experimental results of the anomalous magnetic moment of the muon. our analyses reveal that the ss → τ+ τ- and ss → b b̄ channels reproduce the galactic centre excess, with an emerging dark matter candidate which complies with the bounds from direct detection experiments, measurements of the higgs boson invisible decay width and observations of the dark matter relic abundance. addressing the anomalous magnetic moment of the muon imposes further strong constraints on the model. remarkably, under these conditions, the ss → b b̄ channel still allows for the fitting of the galactic centre. we also comment on a scenario allowed by the model where the ss → τ+ τ- and ss → b b̄ channels have comparable branching ratios, which possibly yield an improved fitting of the galactic centre excess. | muon g - 2 and galactic centre γ-ray excess in a scalar extension of the 2hdm type-x |
an electroweak (ew) sector of the minimal supersymmetric standard model (mssm) with masses of a few hundred gev can account for variety of experimental data, assuming the lightest neutralino to be the lightest supersymmetric (susy) particle: the non-observation at the lhc, searches owing to their small production cross sections, the results for the (upper limit of the) dark matter (dm) relic abundance and the dm direct detection (dd) limits. such a light ew sector can in particular explain the reinforced $4.2σ$ discrepancy between the experimental result for $(g-2)_{μ}$, and its standard model (sm) prediction. using the improved limits on $(g-2)_{μ}$, we review the predictions for the future prospects of the dd experiments. this analysis is performed for several different realizations of dm in the mssm: bino, bino/wino, wino, and higgsino dm. we find that higgsino, wino and one type of bino scenario can be covered by future dd experiments. mixed bino/wino and another type of bino dm can reach dd cross sections below the neutrino floor. in these cases future collider experiments must cover the remaining parameter space. | susy dark matter direct detection prospects based on \\boldsymbol{(g-2)}_{\\boldsymbol{μ}} |
the electrons in graphene for energies close to the dirac point have been found to form strongly interacting fluid. taking this fact into account we have extended previous work on the transport properties of graphene by taking into account possible interactions between the currents and adding the external magnetic field directed perpendicularly to the graphene sheet. the perpendicular magnetic field b severely modifies the transport parameters. in the present approach the quantization of the spectrum and formation of landau levels is ignored. gauge/gravity duality has been used in the probe limit. the dependence on the charge density of the seebeck coefficient and thermoelectric parameters αi j nicely agree with recent experimental data for graphene. the holographic model allows for the interpretation of one of the fields representing the currents as resulting from the dark matter sector. for the studied geometry with electric field perpendicular to the thermal gradient the effect of the dark sector has been found to modify the transport parameters but mostly in a quantitative way only. this makes difficult the detection of this elusive component of the universe by studying transport properties of graphene. | two interacting current model of holographic dirac fluid in graphene |
if dark matter interacts, even weakly, via non-gravitational forces, simulations predict that it will be preferentially scattered towards the trailing edge of the halo during collisions between galaxy clusters. this will temporarily create a non-symmetric mass profile, with a trailing overdensity along the direction of motion. to test this hypothesis, we fit (and subtract) symmetric haloes to the weak gravitational data of 72 merging galaxy clusters observed with the hubble space telescope. we convert the shear directly into excess κ and project in to a one-dimensional profile. we generate numerical simulations and find that the one-dimensional profile is well described with simple gaussian approximations. we detect the weak lensing signal of trailing gas at a 4σ confidence, finding a mean gas fraction of mgas/mdm = 0.13 ± 0.035. we find no evidence for scattered dark matter particles with an estimated scattering fraction of f = 0.03 ± 0.05. finally, we find that if we can reduce the statistical error on the positional estimate of a single dark matter halo to <2.5 arcsec, then we will be able to detect a scattering fraction of 10 per cent at the 3σ level with current surveys. this potentially interesting new method can provide an important independent test for other complimentary studies of the self-interaction cross-section of dark matter. | looking for dark matter trails in colliding galaxy clusters |
we present the design and noise performance of a fully cryogenic (t=4 k) high-electron mobility transistor (hemt)-based charge amplifier for readout of sub-kelvin semiconductor radiation detectors. the amplifier is being developed for use in direct detection dark matter searches such as the cryogenic dark matter search and will allow these experiments to probe weakly interacting massive particle masses below 10 gev/c^2 while retaining background discrimination. the amplifier dissipates ≈ 1 mw of power and provides an open loop voltage gain of several hundreds. the measured noise performance is better than that of jfet-based charge amplifiers and is dominated by the noise of the input hemt. an optimal filter calculation using the measured closed loop noise and typical detector characteristics predicts a charge resolution of σ _q=106 ev (35 electrons) for leakage currents below 4 × 10^{-15} a. | an hemt-based cryogenic charge amplifier for sub-kelvin semiconductor radiation detectors |
dark matter could be made up of dark photons, massive but very light particles whose interactions with matter resemble those of usual photons but suppressed by a small mixing parameter. we analyze the main approaches to dark photon interactions and how they can be applied to direct detection experiments which test different ranges of masses and mixings. a new experiment based on counting dark photons from induced atomic transitions in a target material is proposed. this approach appears to be particularly appropriate for dark photon detection in the mev mass range, extending the constraints in the mixing parameter by up to eight orders of magnitude with respect to previous experiments. | dark photon searches with atomic transitions |
a bevy of light dark matter direct detection experiments have been proposed, targeting spin-independent dark matter scattering. in order to be exhaustive, non-standard signatures that have been investigated in the wimp window including spin-dependent dark matter scattering also need to be looked into in the light dark matter parameter space. in this work, we promote this endeavor by deriving indirect limits on sub-gev spin-dependent dark matter through terrestrial and astrophysical limits on the forces that mediate this scattering. | spin-dependent light dark matter constraints from mediators |
we study interaction of low mass dark matter within beam dump experiments. in particular we study the dipolar dark matter model which assumes that the dark matter couples to standard model particles via its electric or magnetic dipole moment. we analyse the constraints on this model in the context of a particular beam dump experiment e613 conducted in the fermilab. we find that dark matter mass in the range of $1-10$ gev with a magnetic dipole moment between $(0.33-1.5)\times 10^{-7}\mu_b$ and a electric dipole moment between $(0.5-3)\times 10^{-17}$ e-cm. we compare the bounds from other experimental data, such as helioseismological data and direct detection experiments. | detecting dipolar dark matter in beam dump experiments |
the simplest higgs-portal dark matter model is studied in the light of dark matter self-interacting effects on the formation of large scale structures. we show the direct detection limits on the resonant and large mass regions. finally, we also compare these limits with those at the lhc and xenon 1t experiments. | higgs-portal scalar dark matter: scattering cross section and observable limits |
we consider a scenario, within the framework of the minimal supersymmetric standard model, in which dark matter is binolike and dark matter-nucleon spin-independent scattering occurs via the exchange of light squarks which exhibit left-right mixing. we show that direct detection experiments such as lux and supercdms will be sensitive to a wide class of such models through spin-independent scattering. moreover, these models exhibit properties, such as isospin violation, that are not typically observed for the minimal supersymmetric standard model lightest supersymmetric particle if scattering occurs primarily through higgs exchange. the dominant nuclear physics uncertainty is the quark content of the nucleon, particularly the strangeness content. | charged mediators in dark matter scattering with nuclei and the strangeness content of nucleons |
we study the effects of dark matter self-interactions on the local dark matter distribution in selected milky way-like galaxies in the eagle hydrodynamical simulations. the simulations were run with two different self-interacting dark matter models, a constant and velocity-dependent self-interaction cross-section. we find that the local dark matter velocity distribution of the milky way-like halos in the simulations with dark matter self-interactions and baryons are generally similar to those extracted from cold collisionless dark matter simulations with baryons. in both cases, the local dark matter speed distributions agree well with their best fit maxwellian distributions. including baryons in the simulations with or without dark matter self-interactions increases the local dark matter density and shifts the dark matter speed distributions to higher speeds. to study the implications for direct detection, we compute the dark matter halo integrals obtained directly from the simulations and compare them to those obtained from the best fit maxwellian velocity distribution. we find that a maxwellian distribution provides a good fit to the halo integrals of most halos, without any significant difference between the results of different dark matter self-interaction models. | the local dark matter distribution in self-interacting dark matter halos |
the purpose of this paper is to examine the model dependence of the stringent constraints on the gluino mass obtained from the large hadron collider (lhc) experiments by analyzing the run ii data using specific simplified models based on several ad hoc sparticle spectra which cannot be realized even in the fairly generic pmssm models. we first revisit the bounds on the gluino mass placed by the atlas collaboration using the 1l+jets+∕et data. we show that the exclusion region in the mg̃−mχ̃10 plane in the pmssm scenario sensitively depends on the mass hierarchy between the left and right squarks and composition of the lighter electroweakinos and to a lesser extent, other parameters. most importantly, for higgsino-type lighter electroweakinos (except for the lsp), the bound on the gluino mass from this channel practically disappears. however, if such models are confronted by the atlas jets+∕et data, fairly strong limits are regained. thus, in the pmssm, an analysis involving a small number of channels may provide more reliable mass limits. we have also performed detailed analyses on neutralino dark matter (dm) constraints in the models we have studied and have found that for a significant range of lsp masses, the relic density constraints from the wmap/planck data are satisfied and lsp-gluino coannihilation plays an important role in relic density production. we have also checked the simultaneous compatibility of the models studied here with the direct dm detection, and the lhc constraints. | revisiting the gluino mass limits in the pmssm in the light of the latest lhc data and dark matter constraints |
darkside run since mid 2015 a 50-kg-active-mass dual phase liquid argon time projection chamber (tpc), filled with low radioactivity argon from an underground source and produced world class results for both the low mass (< 20 gev/c2) and high mass ( > 100 gev/c2) direct detection search for dark matter. the next stage of the darkside program will be a new generation experiment involving a global collaboration from all the current argon based experiments. darkside-20k, is designed as a 20-tonne fiducial mass dual phase liquid argon tpc with sipm based cryogenic photosensors, and is expected to be free of any instrumental background for an exposure of >100 tonne year. like its predecessor, darkside-20k will be housed at the infn gran sasso (lngs) underground laboratory, and it is expected to attain a wimp-nucleon cross section exclusion sensitivity of 7.4 × 10−48 cm2 for a wimp mass of 1 tev/c2 in a 200 t yr run. darkside-20k will be installed inside a membrane cryostat containing more than 700 t of liquid argon and be surrounded by an active neutron veto based on a gd-loaded acrylic shell. the talk will give the latest updates of the ongoing r&d and prototype tests validating the initial design. a subsequent objective, towards the end of the next decade, will be the construction of the ultimate detector, argo, with a 300 t fiducial mass to push the sensitivity to the neutrino floor region for high mass wimps. | direct detection of dark matter with darkside-20k |
we extend and correct a recently proposed maximum-likelihood halo-independent method to analyze unbinned direct dark matter detection data. instead of the recoil energy as independent variable we use the minimum speed a dark matter particle must have to impart a given recoil energy to a nucleus. this has the advantage of allowing us to apply the method to any type of target composition and interaction, e.g. with general momentum and velocity dependence, and with elastic or inelastic scattering. we prove the method and provide a rigorous statistical interpretation of the results. as first applications, we find that for dark matter particles with elastic spin-independent interactions and neutron to proton coupling ratio fn/fp=-0.7, the wimp interpretation of the signal observed by cdms-ii-si is compatible with the constraints imposed by all other experiments with null results. we also find a similar compatibility for exothermic inelastic spin-independent interactions with fn/fp=-0.8. | extended maximum likelihood halo-independent analysis of dark matter direct detection data |
we study a minimal model of pseudo-dirac dark matter, interacting through transition electric and magnetic dipole moments. motivated by the fact that xenon experiments can detect electrons down to ∼kev recoil energies, we consider o (kev ) splittings between the mass eigenstates. we study the production of this dark matter candidate via the freeze-in mechanism. we discuss the direct detection signatures of the model arising from the down scattering of the heavier state, that are produced in solar upscattering, finding observable signatures at the current and near-future xenon based direct detection experiments. we also study complementary constraints on the model from fixed target experiments, lepton colliders, supernovae cooling and cosmology. we show that the latest xenonnt results rule out parts of the parameter space for this well motivated and minimal dark matter candidate. next generation xenon experiments can either discover or further constrain how strongly inelastic dark matter can interact via the dipole moment operators. | explorations of pseudo-dirac dark matter having kev splittings and interacting via transition electric and magnetic dipole moments |
phenomenological studies of flavored dark matter (fdm) models often have to assume a near-diagonal flavor structure in the coupling matrix in order to remain consistent with bounds from flavor violating processes. in this paper we show that for lepton fdm, such a structure can naturally arise from an extra dimensional setup. the extra dimension is taken to be flat, with the dark matter and mediator fields confined to a brane on one end of the extra dimension, and the higgs field to a brane on the other end. the standard model fermion and gauge fields are the zero modes of corresponding bulk fields with appropriate boundary conditions. global flavor symmetries exist in the bulk and on the fdm brane, while they are broken on the higgs brane. flavor violating processes arise due to the misalignment of bases for which the interactions on the two branes are diagonalized, and their size can be controlled by a choice of the lepton profiles along the extra dimension. by studying the parameter space for the model, we show that when relic abundance and indirect detection constraints are satisfied, the rates for flavor violating processes such as μ →e γ remain far below the experimental limits. | suppressed flavor violation in lepton flavored dark matter from an extra dimension |
in their recent preprint [arxiv:2002.06937], kurinsky, baxter, kahn, and krnjaic assume an unphysical ionization yield for plasmon excitations in order to claim a possible dark matter signal. their proposed signal is not possible based on known physics, but their proposed detection method warrants further investigation. | comment on a dark matter interpretation of excesses in multiple direct detection experiments [arxiv:2002.06937] |
isospin-violating dark matter (ivdm), which couples differently with protons and neutrons, provides a promising mechanism to ameliorate the tension among recent direct detection experiments. assuming dark matter (dm) is non-interacting bosonic asymmetric ivdm, we investigate how the existence of old neutron stars limits the dm-proton scattering cross-section {{σ }p}, especially the effects of the isospin-violating dm-nucleon interactions and the symmetry energy in the equation of state (eos) of isospin asymmetric nuclear matter. our calculations are completely based on general relativity and the structure of neutron stars is obtained by solving the tolman-oppenheimer-volkoff equations with nuclear matter eos constrained by terrestrial experiments. we find that, by considering the more realistic neutron star model rather than a simple uniform neutron sphere as usual, the {{σ }p} bounds from old neutron stars can be varied by more than an order of magnitude depending on the specific values of the dm neutron-to-proton coupling ratio {{f}n}/{{f}p}, and they can be further varied by more than a factor of two depending on the density dependence of the symmetry energy. in particular, we demonstrate that the observed nearby isolated old neutron star psr b1257+12 can set a very strong limit on {{σ }p} for low-mass dm particles (≤slant 20 gev) that reaches a sensitivity beyond the current best limits from direct detection experiments and disfavors the dm interpretation of previously reported positive experimental results, including the ivdm. | old neutron stars as probes of isospin-violating dark matter |
we present two scenarios in the minimal supersymmetric extension of the standard model (mssm) that can lead to an explanation of the excess in the invariant mass distribution of two opposite charged, same flavor leptons, and the corresponding edge at an energy of about 78 gev, recently reported by the cms collaboration. in both scenarios, sbottoms are pair produced, and decay to neutralinos and a b-jet. the heavier neutralinos further decay to a pair of leptons and the lightest neutralino through on-shell sleptons or off-shell neutral gauge bosons. these scenarios are consistent with the current limits on the sbottoms, neutralinos, and sleptons. assuming that the lightest neutralino is stable we discuss the predicted relic density as well as the implications for dark matter direct detection. we show that consistency between the predicted and the measured value of the muon anomalous magnetic moment may be obtained in both scenarios. finally, we define the signatures of these models that may be tested at the 13 tev run of the lhc. | cms kinematic edge from sbottoms |
we consider monojet searches at the large hadron collider (lhc) for spin-1 dark matter that interacts with quarks through a contact operator. if the dark matter particles are produced with longitudinal polarizations, then the production matrix element is enhanced by factors of the energy. we show that this particularly effective search strategy can test models for which the energy suppression scale of the operator is as large as 105 tev . as such, these searches can probe a large class of models for which the contact-operator approximation is valid. we find that for contact operators that permit velocity-independent dark matter-nucleon scattering, lhc monojet searches for spin-1 dark matter are competitive with or far surpass direct-detection searches depending on whether the scattering is spin independent or spin dependent, respectively. | vector dark matter at the lhc |
the direct detection of dark matter is a key problem in astroparticle physics that generally requires the use of deep-underground laboratories for a low-background environment where the rare signals from dark matter interactions can be observed. this work reports on the stawell underground physics laboratory - currently under construction and the first such laboratory in the southern hemisphere - and the associated research program. a particular focus will be given to anu's contribution to sabre, a nai:tl dark matter, direct detection experiment that aims to confirm or refute the long-standing dama result. preliminary measurements of the nai:tl quenching factor and characterisation of the sabre liquid scintillator veto are reported. | sabre and the stawell underground physics laboratory dark matter research at the australian national university |
in this paper, as the third 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 introduce a 3-dimensional effective velocity distribution of halo weakly interacting massive particles (wimps), which, instead of the theoretically prediction of the entire galactic dark matter particles, describes the actual velocity distribution of wimps scattering off (specified) target nuclei in an underground detector. its target and wimp-mass dependences as well as ("annual" modulations of) its "anisotropy" in the equatorial/laboratory and even the galactic coordinate systems will be demonstrated and discussed in detail. 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/). | 3-dimensional effective velocity distribution of halo weakly interacting massive particles scattering off nuclei in direct dark matter detectors |
we explore a model of dark matter (dm) that can explain the reported discrepancy in the muon anomalous magnetic moment and predict a large electric dipole moment (edm) of the muon. the model contains a dm fermion and new scalars whose exclusive interactions with the muon radiatively generate the observed muon mass. constraints from dm direct and indirect detection experiments as well as collider searches are safely evaded. the model parameter space that gives the observed dm abundance and explains the muon g - 2 anomaly leads to the muon edm of dμ ≃ (4-5) × 10−22e cm that can be probed by the projected psi muedm experiment. another viable parameter space even achieves dμ=o (10−21)e cm reachable by the ongoing fermilab muon g − 2 experiment and the future j-parc muon g − 2/edm experiment. | a large muon edm from dark matter |
we study the type-ii first-order electroweak phase transition and dark matter (dm) phenomenology in both real and complex singlet extensions of sm . in the real singlet extension with a bbb z2 symmetry, we show that the parameter regions favored by the phase transition suffer from strong constraints from dm direct detection so that only a negligible fraction (fx~ 10-4-10-5) of dm composed of the real singlet scalar can survive the lux and xenon1t constraints. in the complex singlet s case, we impose a cp symmetry s→ s* to the scalar potential. the real component of s can mix with sm higgs boson while the imaginary component becomes a dm candidate due to the protection of the cp symmetry. by taking into account the current experimental constraints of invisible higgs decays, higgs signal strength measurements, and dark matter detections, we find that there exists a large parameter space for the type-ii electroweak phase transition to occur while explaining all of the dark matter relic density. we identify a subset of parameter space that is promising for future experiments, including the di-higgs and higgs signal strength measurements at the hl-lhc and the dark matter direct detection in the xenonnt project. | electroweak phase transition confronted with dark matter detection constraints |
over almost three decades the taup conference has seen a remarkable momentum gain in direct dark matter search. an important accelerator were first indications for a modulating signal rate in the dama/nai experiment (today dama/libra) reported in 1997. today the presence of an annual modulation observed by dama, which matches in period and phase the expectation for dark matter, is doubtless and supported at > 9σ confidence. despite the positive evidence from the dama experiment the underlying nature of dark matter is still considered an open and fundamental question of nowadays particle physics. no other direct dark matter search experiment could confirm the dama claim up to now; moreover, numerous null-results are in clear contradiction with dama under so-called standard assumptions for the dark matter halo and the interaction mechanism of dark with ordinary matter. as both bear a dependence on the target material, resolving this controversial situation will convincingly only be possible with an experiment using sodium iodide (nai) as target, just like dama. cosinus aims to even go a step further by combining nai with a novel detection approach. dama and all other nai experiments solely measure the scintillation light created by a particle interaction in the nai crystal. cosinus aims to operate nai as a cryogenic calorimeter reading scintillation light and phonon/heat signal. two distinct advantages arise from this approach, a substantially lower energy threshold for nuclear recoils and particle identification on an event-by-event basis. these key benefits will allow cosinus to clarify a possible nuclear recoil origin of the dama signal with comparatively little exposure of o(100kg days) and, thereby, answer a long-standing question of particle physics. today cosinus is in r&d phase; in this contribution we show results from the 2nd prototype, albeit the first one of the final foreseen detector design. the key finding of this measurement is that pure, undoped nai is a truly excellent scintillator at low temperatures: we measure 13.1% of the total deposited energy in the nai crystal in the form of scintillation light (in the light detector). | results of the first nai scintillating calorimeter prototypes by cosinus |
we investigate a scenario in which supersymmetry is broken at a scale ms≥ 1014 gev leaving only a pair of higgs doublets, their superpartners (higgsinos) and a gauge singlet fermion (singlino) besides the standard model fermions and gauge bosons at low energy. the higgsino-singlino mixing induces a small splitting between the masses of the electrically neutral components of higgsinos which otherwise remain almost degenerate in gut scale supersymmetry. the lightest combination of them provides a viable thermal dark matter if the higgsino mass scale is close to 1 tev. the small mass splitting induced by the singlino turns the neutral components of higgsinos into pseudo-dirac fermions which successfully evade the constraints from the direct detection experiments if the singlino mass is ≲ 108 gev. we analyse the constraints on the effective framework, arising from the stability of electroweak vacuum, observed mass and couplings of the higgs, and the limits on the masses of the other scalars, by matching it with the next-to-minimal supersymmetric standard model at ms . it is found that the presence of singlino at an intermediate scale significantly improves the stability of electroweak vacuum and allows a stable or metastable vacuum for almost all the values of tan β while the observed higgs mass together with the limit on the charged higgs mass favours tan β ≲ 3. | pseudo-dirac higgsino dark matter in gut scale supersymmetry |
in this article we investigate the benefits of increasing the maximum nuclear recoil energy analysed in dark matter (dm) direct detection experiments. we focus on elastic dm-nucleus interactions, and work within the framework of effective field theory (eft) to describe the scattering cross section. in agreement with previous literature, we show that an increased maximum energy leads to more stringent upper bounds on the dm-nucleus cross section for the eft operators, especially those with an explicit momentum dependence. in this article we extend the energy region of interest (roi) to show that the optimal values of the maximum energy for xenon and argon are of the order of 500 kev and 300 kev, respectively. we then show how, if a signal compatible with dm is observed, an enlarged energy roi leads to a better measurement of the dm mass and couplings. in particular, for a xenon detector, dm masses of the order of 200 gev (2 tev) or lower can be reconstructed for momentum-independent (-dependent) operators. we also investigate three-dimensional parameter reconstruction and apply it to the specific case of scalar dm and anapole dm. we find that opening the energy roi is an excellent way to identify the linear combination of momentum-dependent and momentum-independent operators, and it is crucial to correctly distinguish these models. finally, we show how an enlarged energy roi also allows us to test astrophysical parameters of the dm halo, such as the dm escape speed. | opening the energy window on direct dark matter detection |
experimental collaborations for the large hadron collider conducted many and various searches for supersymmetry. in the absence of signals, lower limits were put on sparticle masses but usually within frameworks with (over-) simplifications relative to the entire indications by supersymmetry models. for complementing current interpretations of experimental bounds, we introduce a 30-parameters version of the r-parity conserving minimal supersymmetric standard model (mssm-30). using a sample of the mssm-30 which are in harmony with cold dark matter, flavour and precision electroweak constraints, we explicitly show the prospects for assessing neutralino candidate dark matter in contrast to future searches for supersymmetry. the mssm-30 parameters regions that are beyond reach to dark matter direct detection experiments could be probed by future hadron-hadron colliders. | future prospects for the minimal supersymmetric standard model |
we revisit the simplest model of higgs portal fermionic dark matter. the dark matter in this scenario is thermally produced in the early universe due to the interactions with the higgs boson which is described by a non-renormalisable dimension-5 operator. the dark matter-higgs scattering amplitude grows as $\propto \sqrt{s}$, signalling a breakdown of the effective description of the higgs-dark matter interactions at large enough (compared to the mass scale $\lambda$ of the dimention-5 operator) energies. therefore, in order to reliably compute higgs-dark matter scattering cross sections, we employ the k-matrix unitarisation procedure. to account for the desired dark matter abundance, the unitarised theory requires appreaciably smaller $\lambda$ than the non-unitarised version, especially for dark matter masses around and below the higgs resonance, $m_{\chi}\lesssim 65$ gev, and $m_{\chi}\gtrsim $ few tev. consequently, we find that the pure scalar cp-conserving model is fully excluded by current direct dark matter detection experiments. | more stringent constraints on the unitarised fermionic dark matter higgs portal |
we show that the existence of a sub-dominant form of dark matter, made of dark "antiatoms" of mass m~ 1 tev and size ȧ0~ 3 fm, can explain the results of direct detection experiments, with a positive signal in dama/nai and dama/libra and no signal in other experiments. the signal comes from the binding of the dark antiatoms to thallium, a dopant in dama, and is not present for the constituent atoms of other experiments. the dark antiatoms are made of two particles oppositely charged under a dark u(1) symmetry and can bind to terrestrial atoms because of a kinetic mixing between the photon and the massless dark photon, such that the dark particles acquire an electric millicharge ~ ± 5.10-4e. this millicharge enables them to bind to high-z atoms via radiative capture, after they thermalize in terrestrial matter through elastic collisions. | dark antiatoms can explain dama |
earth's rotation about the sun produces an annual modulation in the expected scattering rate at direct dark matter detection experiments. the annual modulation as a function of the recoil energy er imparted by the dark matter particle to a target nucleus is expected to vary depending on the detector material. however, for most interactions a change of variables from er to vmin, the minimum speed a dark matter particle must have to impart a fixed er to a target nucleus, produces an annual modulation independent of the target element. we recently showed that if the dark matter-nucleus cross section contains a non-factorizable target and dark matter velocity dependence, the annual modulation as a function of vmin can be target dependent. here we examine more extensively the necessary conditions for target-dependent modulation, its observability in present-day experiments, and the extent to which putative signals could identify a dark matter-nucleus differential cross section with a non-factorizable dependence on the dark matter velocity. | prospects for detection of target-dependent annual modulation in direct dark matter searches |
we demonstrate that the observation of old strange quark stars (sqss) can set important limits on the scattering cross-sections {σ }q between light quarks and non-interacting scalar dark matter (dm). by analyzing a set of 1403 solitary pulsar-like compact stars in the milky way, we find that the old solitary pulsar psr j1801-0857d can set the most stringent upper limits on {σ }q or the cross-sections {σ }p between dm and protons. by converting {σ }q into {σ }p based on effective operator analyses, we show that the resulting {σ }p limit, by assuming psr j1801-0857d is an sqs, is comparable with that of the current direct detection experiments in terrestrial labs but weaker by several orders of magnitude than that obtained by assuming psr j1801-0857d is a neutron star (ns), which requires an extremely small {σ }p far beyond the limits of direct detection experiments. our findings imply that old pulsars are more likely to be identified as sqss than as nss in future terrestrial experiments observing scalar dm. | strange quark stars as a probe of dark matter |
the direct detection of dark matter constituents, in particular the weakly interacting massive particles (wimps), is considered central to particle physics and cosmology. in this paper we study transitions to the excited states, possible in nuclei which have sufficiently low-lying excited states. examples considered previously were the first excited states of 127i, 129xe and 83kr. here, we examine 125te, which offers some advantages and is currently being considered as a target. in all these cases the extra signature of the gamma rays following the de-excitation of these states has definite advantages over the purely nuclear recoil and in principle such a signature can be exploited experimentally. a brief discussion of the experimental feasibility is given in the context of the cuore experiment. | inelastic wimp-nucleus scattering to the first excited state in 125te |
this white paper summarizes the activities of the brazilian community concerning dark matter physics and highlights the importance of financial support to brazilian groups that are deeply involved in experimental endeavours. the flagships of the brazilian dark matter program are the cherenkov telescope array, darkside, sbn and lhc experiments, but we emphasize that smaller experiments such as damic and connie constitute important probes to dark sectors as well and should receive special attention. small experimental projects showing the potential to probe new regions of parameter space of dark matter models are encouraged. on the theoretical and phenomenological side, some groups are devoted to astrophysical aspects such as the dark matter density profile while others explore the signature of dark matter models at colliders, direct and indirect detection experiments. in summary, the brazilian dark matter community that was born not long ago has grown tremendously in the past years and now plays an important role in the hunt for a dark matter particle. | brazilian community report on dark matter |
we study a new physics scenario with two inert and one active scalar doublets, hence a 3-higgs doublet model (3hdm). we impose a z2×z2' symmetry onto such a 3hdm with one inert doublet odd under the z2 transformation and the other odd under the z2' one. such a construction leads to a two-component dark matter (dm) model. it has been shown that, when there is a sufficient mass difference between the two dm candidates, it is possible to probe the light dm candidate in the nuclear recoil energy in direct detection experiments and the heavy dm component in the photon flux in indirect detection experiments. with the dm masses at the electroweak scale, we show that, independently of astrophysical probes, this model feature can be tested at the large hadron collider via scalar cascade decays in final states. we study several observable distributions whose shapes hint at the presence of the two different dm candidates. | complementary collider and astrophysical probes of multi-component dark matter |
we report on the observation of impact ionization processes involving shallow impurity states in a sub-kelvin, high-purity n-type germanium detector similar to those used by direct detection dark matter experiments such as the cryogenic dark matter search. an optical fiber is used to generate packets of charge carriers near one surface of the detector. the charge carriers drift to the opposite surface by application of an electric field. the resulting drift current is measured by a high-speed charge amplifier. the onset of impact ionization for both electron and hole transport is clearly observed in the drift current as the applied electric field is increased above ≈ 5 v/cm. we present the effective charge collection efficiency and trapping length as a function of applied electric field for electrons and holes. we estimate the impact ionization cross section to be on the order of 5× 10^{-13} mathrm {cm}^2. | observation of impact ionization of shallow states in sub-kelvin, high-purity germanium |
well-motivated electroweak dark matter is often hosted by an extended electroweak sector that also contains new lepton pairs with masses near the weak scale. in this study, we explore such electroweak dark matter by combining dark matter direct detection experiments and high-luminosity lhc probes of new lepton pairs. using z- and w-associated electroweak processes with two or three lepton final states, we show that depending on the overall coupling constant, dark matter masses of up to 170-210 gev can be excluded at the $2\sigma$ level and those up to $175-205$ gev can be discovered at the $5\sigma$ level at the 14 tev lhc with integrated luminosities of 300 fb $^{-1}$ and 3000 fb $^{-1}$ , respectively. * supported by national natural science foundation of china (11775039), the chinese scholarship council and the fundamental research funds for the central universities at cqu with (cqu2017hbrc1b05) | probing electroweak dark matter at 14 tev lhc |
we present a summary of the current status of searches for dark matter at the lhc from the atlas and cms experiments. for various assumptions in the simplified parameter space, the lhc exclusions is complementary to direct detection results. mono-object analyses in search of dark matter and various analyses searching for dark matter mediators are presented. | dark matter searches at the lhc |
we investigate the vacuum stability and perturbativity of a pseudoscalar portal dark matter (dm) model with a dirac dm candidate, through the renormalization group equation analysis at one-loop order. the model has a particular feature which can evade the direct detection upper bounds measured by xenon100 and even that from planned experiment xenon1t. we first find the viable regions in the parameter space which will give rise to correct dm relic density and comply with the constraints from higgs physics. we show that for a given mass of the pseudoscalar, the mixing angle plays no significant role in the running of the couplings. then we study the running of the couplings for various pseudoscalar masses at mixing angle θ =6^\circ , and find the scale of validity in terms of the dark coupling, {λ }d. depending on our choice of the cutoff scale, the resulting viable parameter space will be determined. | renormalization group equation analysis of a pseudoscalar portal dark matter model |
the first-year results from deap-3600, a single-phase liquid argon direct-detection dark matter experiment, were recently reported. at first sight, they seem to provide no new constraints, as the limit lies well within the region already excluded by three different xenon experiments: lux, pandax-ii, and xenon1t. we point out, however, that this conclusion is not necessarily true, for it is based on the untested assumption that the dark matter particle couples equally to protons and neutrons. for the more general case of isosping-violating dark matter, we find that there are regions in the parameter space where deap-3600 actually provides the most stringent limits on the dark matter-proton spin-independent cross section. such regions correspond to the so-called xenonphobic dark matter scenario, for which the neutron-to-proton coupling ratio is close to -0.7. our results seem to signal the beginning of a new era in which the complementarity among different direct detection targets will play a crucial role in the determination of the fundamental properties of the dark matter particle. | new constraints on xenonphobic dark matter from deap-3600 |
in this note we revisit the susy effects in rb under current experimental constraints including the lhc higgs data, the b-physics measurements, the dark matter relic density and direct detection limits, as well as the precision electroweak data. we first perform a scan to figure out the currently allowed parameter space and then display the susy effects in rb. we find that although the susy parameter space has been severely restrained by current experimental data, both the general mssm and the natural-susy scenario can still alter rb with a magnitude sizable enough to be observed at future z-factories (ilc, cepc, fcc-ee, super z-factory) which produce 109-1012z-bosons. to be specific, assuming a precise measurement δrb = 2.0 ×10-5 at fcc-ee, we can probe a right-handed stop up to 530 gev through chargino-stop loops, probe a sbottom to 850 gev through neutralino-sbottom loops and a charged higgs to 770 gev through the higgs-top quark loops for a large tan β. the full one-loop susy correction to rb can reach 1 ×10-4 in natural susy and 2 ×10-4 in the general mssm. | susy effects in rb: revisited under current experimental constraints |
we explore a scenario where dark matter (dm) couples to the standard model mainly via a scalar mediator s that is odd under a z_2 symmetry, leading to interesting collider signatures. in fact, if linear interactions with the mediator are absent the most important dm production mechanisms at colliders could lead to final states with missing transverse energy (met) in association with at least two fermions, such as di-jet or di-electron signatures. the framework we consider is model-independent, in a sense that it is only based on symmetry and formulated in the (extended) dm effective field theory (e dmeft) approach. moreover, it allows to address the smallness of first-generation fermion masses via suppressed z_2 breaking effects. from a di-jet + met analysis at the lhc, we find rather loose bounds on the effective s-s-dm-dm interactions, unless the mediator couples very strongly to sm fermions, while a future e^+ e^- collider, such as clic, could deliver tighter constraints on the corresponding model parameters, given the mediator is leptophilic. we finally highlight the parameter space that allows to produce the observed dm density, including constraints from direct-detection experiments. | di-jet/e+e-+met to probe z_2-odd mediators to the dark sector |
this article is an addendum to [s. baek et al., phys. rev. d 90, 055014 (2014)., 10.1103/physrevd.90.055014]. here, we discuss the invisible higgs decay width γhinv in the higgs portal vector dark matter (vdm) model in the limit mv→0+. in the effective field theory (eft) approach where the vdm mass is attributed to the stückelberg mechanism, (γhinv)eft is divergent, which is unphysical and puzzling. on the other hand (γhinv)uv becomes finite in a uv completion, where the vdm mass is generated by the dark higgs mechanism. then we can take the limit mv→0+ by taking either (i) the dark gauge coupling gx→0+ with a fixed dark higgs vacuum expectation value vφ, or (ii) vφ→0+ with a fixed gx. such a difference in the behavior of γhinv in the massless vdm limit demonstrates another limitation of eft for the higgs portal vdm, and the importance of gauge-invariant and renormalizable models for the higgs portal vdm. | addendum to "invisible higgs decay width versus dark matter direct detection cross section in higgs portal dark matter models" |
in the dark matter (dm) direct detection community, the absence of convincing signals has become a "new normal" for decades. among other possibilities, the "new normal" might indicate that dm-matter interactions could generate not only the hypothetical nr (nuclear recoil) events but also the er (electron recoil) ones, which have often been tagged as backgrounds historically. further, we argue that er and nr-like dm signals could co-exist in a dm detector's same dataset. so in total, there would be three scenarios we can search for dm signals: (i) er excess only, (ii) nr excess only, and (iii) er and nr excesses combined. to effectively identify any possible dm signal under the three scenarios, a dm detector should (a) have the minimum er and nr backgrounds and (b) be capable of discriminating er events from nr ones. accordingly, we introduce the newly established project, aletheia, which implements liquid helium-filled tpcs (time projection chambers) in hunting for dm. thanks to the nearly single-digit number of er and nr backgrounds on 1 ton*yr exposure, presumably, the aletheia detectors could identify any form of dm-induced excess in its roi (research of interest). as far as we know, aletheia is the first dm direct detection experiment claiming such an inclusive search; conventional detectors search dm mainly on the "er excess only" and/or the "nr excess only" channel, not the "er and nr excesses combined" channel. | search for er and/or nr-like dark matter signals with the especially low background liquid helium tpcs |
quantum theory, general relativity, the standard model of particle physics, and the $\lambda$cdm model of cosmology have all been spectacularly successful within their respective regimes of applicability, but each of these descriptions also has clear limitations. here we propose a fundamental theory which (like string theory) is based on higher dimensions (with an internal space), a form of supersymmetry, important topological structures, and the implication of a multiverse. our universe is the product of two vortex-like (or instanton-like) field configurations -- one in 4-dimensional external spacetime, with the big bang at its origin, and the other in a 10-dimensional internal space, which automatically yields an $so(10)$ grand-unified gauge theory. lorentz invariance requires a breaking of the initial primitive supersymmetry, as the initial (unphysical) bosonic fields are modified and combined to from physical fields. there is then a new interpretation of all scalar boson sectors -- including but extending the higgs and sfermion sectors. this last feature predicts a novel dark matter wimp with no (nongravitational) interactions except second-order gauge couplings to $w$ and $z$ bosons. calculations and estimates of the relevant cross-sections for this particle demonstrate that (1)~it may be detectable within the next few years in xe-based direct-detection experiments, (2)~it may be observable within about 15 years at the high-luminosity lhc, and (3)~it may already have been detected in the gamma rays observed by fermi-lat and antiprotons observed by ams-02. the reinterpretation of scalar boson fields also implies a new phenomenology for sfermions, with reduced cross-sections. there is then a unified picture which may explain why dark matter wimps and electroweak-scale sparticles have not yet been detected. | the cosmological constant, dark matter, supersymmetry, and other unsolved problems from a fresh perspective |
the complementarity of direct, indirect and collider searches for dark matter has improved our understanding concerning the properties of the dark matter particle. in this short review, we present a step toward the fundamental nature of dark matter with direct detection experiments only, go through some of the potential dark matter signals in gamma-rays, x-rays, and anti-matter, and lastly discuss the prospects of wimps in the next decade. | wimp theory review |
if dm-matter scatterings are assumed to occur in a detector's target material, collisions will naturally take place inside the bulk of planets and stars as well. for large cross sections, these scatterings might occur in the earth or sun even prior to the detection. in this thesis, we study the impact of these pre-detection scatterings on direct searches of light dm with the use of monte carlo (mc) simulations. by simulating the trajectories and scatterings of many individual dm particles in the earth or sun, we determine the local distortions of the statistical properties of dm at any detector caused by elastic dm-nucleus collisions. scatterings inside the earth distort the underground dm density and velocity distribution. any detector moves periodically through these inhomogeneities due to the earth's rotation, and the expected event rate will vary throughout a sidereal day. using mc simulations, we can determine the exact amplitude and phase of this diurnal modulation for any experiment. for even higher scattering probabilities, collisions in the overburden above the typically underground detectors start to attenuate the incoming dm flux. the critical cross section above which an experiment loses sensitivity to dm itself is determined for a variety of dm-nucleus and dm-electron scattering experiments and different interaction types. furthermore, we develop the idea that sub-gev dm particles can enter the sun, gain kinetic energy by colliding on hot nuclei and get reflected with great speeds. by deriving an analytic expressions for the particle flux from solar reflection via a single scattering, we demonstrate the prospects of future experiments to probe reflected dm and extend their sensitivity to lower masses than accessible by halo dm alone. finally, we present first results for mc simulations of solar reflections taking into account the effect of multiple scatterings. | dark matter in the earth and the sun -- simulating underground scatterings for the direct detection of low-mass dark matter |
we investigate the impact of uncertainty in the velocity distribution of dark matter on direct detection experiments. we construct an multinomial prior with a hyperparameter β that describes the strength of our belief in an isotropic maxwell-boltzmann velocity distribution. by varying β, we interpolate between a halo-independent and halo-dependent analysis. we present a novel approximation for the marginalisation of this prior that is applicable to any counting experiment. with this formula, we investigate the impact of the uncertainty in limits from xenon1t. for dark matter masses greater than about 60 gev, we find extremely mild sensitivity to the distribution. below about 60 gev, the limit weakens by less than an order of magnitude if we assume an isotropic distribution in the galactic frame. if we permit anisotropic distributions, the limit further weakens, but at most by about two orders of magnitude. lastly, we check the impact of parametric uncertainties and discuss the possible inclusion and impact of our technique in global fits. | non-parametric uncertainties in the dark matter velocity distribution |
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