Light Dark Matter Research Articles

Is Light Neutralino Thermal Dark Matter in the Phenomenological Minimal Supersymmetric Standard Model Ruled Out?

We explore the parameter space of the phenomenological minimal supersymmetric standard model with a light neutralino thermal dark matter (m_{χ[over ˜]_{1}^{0}}≤m_{h}/2) that is consistent with current collider and astrophysical constraints. We consider both positive and negative values of the higgsino mass parameter (μ). Our investigation shows that the recent experimental results from the LHC as well as from direct detection searches for dark matter by the LUX-ZEPLIN Collaboration rule out the Z-funnel region for the μ>0 scenario. The same results severely restrict the h-funnel region for positive μ; however, the allowed points can be probed easily with few more days of data from the LUX-ZEPLIN experiment. In the μ<0 scenario, we find that very light higgsinos in both the Z and h funnels might survive the present constraints from the electroweakino searches at the LHC, and dedicated efforts from experimental collaborations are necessary to make conclusive statements about their present status.

Exploring coherent elastic neutrino-nucleus scattering of reactor neutrinos with the NUCLEUS experiment

The NUCLEUS experiment aims to perform a high-precision measurement of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) at the EdF Chooz B nuclear power plant in France. CEvNS is a unique process to study neutrino properties and to search for physics beyond the Standard Model. The study of CEvNS is also important for light Dark-Matter searches. It could be a possible irreducible background for high-sensitivity Dark-Matter experiments. NUCLEUS is an experiment under construction based on ultra-low threshold (∼20 eV20eV_{nr}) cryogenic calorimeters, operated at tens-of-mK temperatures.

Status and future prospects of the NEWS-G experiment

The NEWS-G collaboration is searching for light dark matter using spherical proportional counters. Access to the mass range from 50 MeV to 10 GeV is enabled by the combination of low energy threshold, light gaseous targets (H, He, Ne), and highly radio-pure detector construction. Several of the recent developments that have paved the way for the operation of a new 140 cm in diameter, spherical proportional counter are presented. Constructed and commissioned at LSM using 4N copper with a 500\muμxm electroplated inner layer, the detector is now installed in SNOLAB, where it has begun data taking. Building on the electroplating of the current detector, the collaboration construct its next detector directly in the underground laboratory, using ultra-pure copper electroforming. The design and construction of ECUME, a 140 cm in diameter spherical proportional counter fully electroformed underground is discussed, along with the potential to achieve sensitivity reaching the neutrino floor in light Dark Matter searches with a next-generation detector.

DELight: A Direct search Experiment for Light dark matter with superfluid helium

To reach ultra-low detection thresholds necessary to probe unprecedentedly low Dark Matter masses, target material alternatives and novel detector designs are essential. One such target material is superfluid ^44He which has the potential to probe so far uncharted light Dark Matter parameter space at sub-GeV masses. The new “Direct search Experiment for Light dark matter”, DELight, will be using superfluid helium as active target, instrumented with magnetic micro-calorimeters. It is being designed to reach sensitivity to masses well below 100 MeV in Dark Matter-nucleus scattering interactions.

Sub-GeV dark matter searches with EDELWEISS: New results and prospects

The Edelweiss collaboration performs light Dark Matter (DM) particles searches with germanium bolometer collecting charge and phonon signals. Thanks to the Neganov-Trofimov-Luke (NTL) effect, a RMS resolution of 4.46 electron-hole pairs was obtained on a massive (200g) germanium detector instrumented with a NbSi Transition Edge Sensor (TES) operated underground at the Laboratoire Souterrain de Modane (LSM). This sensitivity made possible a search for WIMP using the Migdal effect down to 32 MeV/C^{2}2 and exclude cross-sections down to 10^{-29}−29 cm^22. It is the first measurement in cryogenic germanium with such thermal sensor, proving the high relevance of this technology. Furthermore, such TES have shown sensitivity to out-of-equilibrium phonons, paving the way for EDELWEISS new experience CRYOSEL. This is an important step in the development of Ge detectors with improved performance in the context of the EDELWEISS-SubGeV program.

Directional direct detection of light dark matter up-scattered by cosmic rays from direction of the Galactic center

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.

THE ADJECTIVES LIGHT AND DARK IN ASTROPHYSICAL TEXTS: A CORPUS STUDY

The aim of this paper is to analyze the uses of the lexemes light and dark in astrophysical texts. The research questions concern not only their frequencies and use in specialized terms, but also the contexts in which they tend to occur. We are mainly interested in the basic meanings of the adjectives light and dark, relating to visual perception. &#x0D; For the purposes of our research, we compiled a corpus of abstracts extracted from nine scientific journals specializing in astrophysics. The software employed to create the corpus was AntConc Version 4.2.0.&#x0D; The lexeme light occurs in the corpus 1,478 times, including 867 occurrences as an adjective, whereas the lexeme dark is found 1,610 times, including 1,473 occurrences as an adjective. The most frequent word combinations include the following ones: light curve, light source, light travel, light yield, light time, light intensity; dark matter, dark energy, dark sector, dark universe, dark fluid, dark spot, dark halo.&#x0D; The most popular word combinations including light and dark are scientific terms, e. g. light curve, dark matter and dark energy. The most frequent adjectival uses of light relate to the phenomenon of light, not to the qualities of being bright or pale. The identified expressions could be paraphrased as N of light, e. g. light source &gt; source of light. On the contrary, dark – as used in the most frequent expressions – refers to the quality of being ‘devoid of light’ and ‘of low lightness’.

Jet substructure probe to unfold singlet-doublet dark matter in the presence of non-standard cosmology

We examine the singlet-doublet fermionic dark matter model, where the non-thermal production of the dark matter in light of a non-standard cosmology demands a significantly large interaction rate than the typical radiation-dominated Universe. Despite being a model of freeze-in light dark matter and heavy mediator, the characteristic long-lived particle searches at the collider experiment and the displaced vertex signature do not help in probing such a dark sector since this non-standard interaction mandates nearly prompt decay. We make a counterproposal to probe such signal with di-fat-jets generated from the boosted decays of massive vector bosons and Standard Model Higgs, along with the substantial missing transverse momentum to probe the dark matter at LHC. Interestingly, substructure variables associated with these fat jets have an additional handle to tackle the extensive QCD background as it encodes implicit footmarks of their origin. We adopt the multivariate analysis with the booted decision tree to constrain the measured relic density allowed parameter space of dark matter in the presence of the modified cosmological scenario. Our study shows how the non-trivial expansion affects dark matter production in the early Universe and alters the required search strategies at colliders. This probe provides the best discovery prospect at the HL-LHC for extended parameter space now opened up in the dark sector.

Search for Light Dark Matter with Ionization Signals in the PandaX-4T Experiment.

We report the search results of light dark matter through its interactions with shell electrons and nuclei, using the commissioning data from the PandaX-4T liquid xenon detector. Low energy events are selected to have an ionization-only signal between 60 to 200 photoelectrons, corresponding to a mean nuclear recoil energy from 0.77 to 2.54keV and electronic recoil energy from 0.07 to 0.23keV. With an effective exposure of 0.55 tonne·year, we set the most stringent limits within a mass range from 40 MeV/c^{2} to 10 GeV/c^{2} for pointlike dark matter-electron interaction, 100 MeV/c^{2} to 10 GeV/c^{2} for dark matter-electron interaction via a light mediator, and 3.2 to 4 GeV/c^{2} for dark matter-nucleon spin-independent interaction. For DM interaction with electrons, our limits are closing in on the parameter space predicted by the freeze-in and freeze-out mechanisms in the early Universe.

Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

Probing supersymmetry breaking scale with atomic clocks

The supersymmetry (SUSY) breaking mechanism inevitably predicts the existence of the sgoldstinos, which can play the role of wave-like dark matter. Due to the ubiquitous coupling to the electromagnetic fields, the light scalar sgoldstino dark matter can lead to the variance of the fine-structure constant. With the precise atomic clock data, we find the SUSY breaking scale F can be probed up to the GUT scale in the sgoldstino mass range of 10−22 eV <mϕ<4×10−7 eV.

Millimeter‐Wave WISP Search with Coherent Light‐Shining‐Through‐a‐Wall Toward the STAX Project

AbstractA dark photon is one of the simplest extensions of the Standard Model of particle physics and can be a dark matter candidate. Dark photons kinetically mix with ordinary photons. The mass range from 10−4to 10−3 eV of such dark photons is underconstrained by laboratory‐based experiments and a new search is therefore motivated. In this mass range, dark photons behave like waves rather than particles and the corresponding electromagnetic waves are in the millimeter‐wave range. The technical difficulties of the millimeter waves have prevented so far dark photon experiments in this mass range. The use of coherent millimeter waves to search for dark photons in a Light‐Shining‐through‐a‐Wall (LSW) experiment is proposed. The merits and limitations of coherent wave detection are clarified and the potential of single photon sensors at microwaves is investigated. Development of millimeter‐wave technology is not only limited to dark photons. Technically, an experiment for dark photons by using electromagnetic waves resembles that for axions, another light dark matter candidate, with static magnetic fields. This paper represents an essential step toward axion LSW in the millimeter‐wave range (Sub‐THz‐AXion experiment; STAX) as a potential successor of an on‐going experiment in infrared.

CMB and Lyman-α constraints on dark matter decays to photons

Dark matter energy injection in the early universe modifies both the ionization history and the temperature of the intergalactic medium.In this work, we improve the CMB bounds on sub-keV dark matter and extend previous bounds from Lyman-α observations to the same mass range, resulting in new and competitive constraints on axion-like particles (ALPs) decaying into two photons.The limits depend on the underlying reionization history, here accounted self-consistently by our modified version of the publicly available DarkHistory and CLASS codes. Future measurements such as the ones from the CMB-S4 experimentmay play a crucial, leading role in the search for this type of light dark matter candidates.

Analytic Approach to Light Dark Matter Propagation.

If dark matter interacts too strongly with nuclei, it could be slowed to undetectable speeds in Earth's crust or atmosphere before reaching a detector. For sub-GeV dark matter, approximations appropriate for heavier dark matter fail, necessitating the use of computationally expensive simulations. We present a new, analytic approximation for modeling attenuation of light dark matter in Earth. We show that our approach agrees well with MonteCarlo results, and can be much faster at large cross sections. We use this method to reanalyze constraints on subdominant dark matter.

New strong bounds on sub-GeV dark matter from boosted and Migdal effects

Due to the low nuclear recoils, sub-GeV dark matter (DM) is usually beyond the sensitivity of the conventional DM direct detection experiments. The boosted and Migdal scattering mechanisms have been proposed as two new complementary avenues to search for light DM. In this study, we consider the momentum-transfer effect in the DM-nucleus scattering to derive the new bounds on sub-GeV DM for these two scenarios. We show that such an effect is sizable so that the existing bounds on the DM-nucleus scattering cross section can be improved significantly.

Impact of high-scale Seesaw and Leptogenesis on inflationary tensor perturbations as detectable gravitational waves

We discuss the damping of inflationary gravitational waves (GW) that re-enter the horizon before or during an epoch, where the energy budget of the universe is dominated by an unstable right handed neutrino (RHN), whose out of equilibrium decay releases entropy. Starting from the minimal Standard Model extension, motivated by the observed neutrino mass scale, with nothing more than 3 RHN for the Seesaw mechanism, we discuss the conditions for high scale leptogenesis assuming a thermal initial population of RHN. We further address the associated production of potentially light non-thermal dark matter and a potential component of dark radiation from the same RHN decay. One of our main findings is that the frequency, above which the damping of the tensor modes is potentially observable, is completely determined by successful leptogenesis and a Davidson-Ibarra type bound to be at around 0.1 Hz. To quantify the detection prospects of this GW background for various proposed interferometers such as AEDGE, BBO, DECIGO, Einstein Telescope or LISA we compute the signal-to-noise ratio (SNR). This allows us to investigate the viable parameter space of our model, spanned by the mass of the decaying RHN {M}_1gtrsim 2.4times {10}^8textrm{GeV}cdot sqrt{2times {10}^{-7}textrm{eV}/{tilde{m}}_1} (for leptogenesis) and the effective neutrino mass parameterizing its decay width {tilde{m}}_1 < 2.9 × 10−7 eV (for RHN matter domination). Thus gravitational wave astronomy is a novel way to probe both the Seesaw and the leptogenesis scale, which are completely inaccessible to laboratory experiments in high scale scenarios.

Combination of searches for invisible decays of the Higgs boson using 139 fb−1 of proton-proton collision data at [formula omitted] TeV collected with the ATLAS experiment

Many extensions of the Standard Model predict the production of dark matter particles at the LHC. Sufficiently light dark matter particles may be produced in decays of the Higgs boson that would appear invisible to the detector. This Letter presents a statistical combination of searches for H→invisible decays where multiple production modes of the Standard Model Higgs boson are considered. These searches are performed with the ATLAS detector using 139 fb−1 of proton–proton collisions at a centre–of–mass energy of ▪ at the LHC. In combination with the results at ▪ and ▪, an upper limit on the H→invisible branching ratio of 0.107 (0.077) at the 95% confidence level is observed (expected). These results are also interpreted in the context of models where the 125 GeV Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross-section of weakly interacting massive particles and nucleons.

Constraining light thermal inelastic dark matter with NA64

A vector portal between the Standard Model and the dark sector is a predictive and compelling framework for thermal dark matter. Through co-annihilations, models of inelastic dark matter (iDM) and inelastic Dirac dark matter (i2DM) can reproduce the observed relic density in the MeV to GeV mass range without violating cosmological limits. In these scenarios, the vector mediator behaves like a semi-visible particle, evading traditional bounds on visible or invisible resonances, and uncovering new parameter space to explain the muon (g-2) anomaly. By means of a more inclusive signal definition at the NA64 experiment, we place new constraints on iDM and i2DM using a missing energy technique. With a recast-based analysis, we contextualize the NA64 exclusion limits in parameter space and estimate the reach of the newly collected and expected future NA64 data. Our results motivate the development of an optimized search program for semi-visible particles, in which fixed-target experiments like NA64 provide a powerful probe in the sub-GeV mass range.

Snowmass white paper: Light dark matter direct detection at the interface with condensed matter physics

Snowmass white paper: Light dark matter direct detection at the interface with condensed matter physics

Directional detection of light dark matter in superconductors

Superconducting detectors have been proposed as outstanding targets for the direct detection of light dark matter scattering at masses as low as a keV. We study the prospects for directional detection of dark matter in isotropic superconducting targets from the angular distribution of excitations produced in the material. We find that dark matter scattering produces initial excitations with an anisotropic distribution, and further show that this directional information can be preserved as the initial excitations relax. Our results demonstrate that directional detection is possible for a wide range of dark matter masses, and they pave the way for light dark matter discovery with bulk superconducting targets.