Weakly Interacting Massive Particle Dark Matter Research Articles

LUX, ZEPLIN and LUX-ZEPLIN: Developments in liquid xenon detectors and the search for WIMP dark matter

The search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs) remains one of the enduring scientific and technical challenges in physics despite four decades of research. A discovery would have broad implications for particle physics, astrophysics, and cosmology. Over the last 15 years, liquid xenon time projection chambers have been on the forefront of this search, starting with detector masses on the 10-kg scale and now reaching the 10-tonne scale. Advances in a number of technical areas across xenon-detector collaborations worldwide, along with progress in related techniques in low-background and liquid noble detectors, have led to significant and steady improvements in sensitivity. In this contribution to Nobel Symposium 182, I highlight several of the contributions made by the LUX, ZEPLIN, and LUX-ZEPLIN (LZ) collaborations, and members thereof. I also discuss briefly the status of the currently-operating and world-leading LZ experiment.

Probing the impact of WIMP dark matter on universal relations, GW170817 posterior, and radial oscillations

ABSTRACT In this study, we investigate the impact of weakly interacting massive particles (WIMPs) dark matter (DM) on C–Λ universal relations, GW170817 posterior, and radial oscillations of neutron stars (NSs) by considering the interactions of uniformly trapped neutralinos as a DM candidate with the hadronic matter through the exchange of the Higgs boson within the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The hadronic equation of state (EOS) is modelled using the relativistic mean-field (RMF) formalism with IOPB-I, G3, and quark–meson coupling (QMC)-RMF series parameter sets. The presence of DM softens the EOS at both the background and the perturbation levels that implies a small shift to the left in the posterior accompanied by a much larger jump in the left of the mass–radius curves with increasing DM mass. It is observed that EOSs with DM also satisfy the C–Λ universality relations among themselves but get slightly shifted to the right in comparison to that without considering DM. Additionally, we find that the inclusion of DM allows the mass–radius (M–R) curves to remain consistent with observational constraints for HESS J1731−347, indicating the possibility of classifying it as a dark matter-admixed neutron star (DMANS). Moreover, we explore the impact of DM on the radial oscillations of pulsating stars and investigate the stability of NSs. The results demonstrate a positive correlation between the mass of DM and the frequencies of radial oscillation modes.

Search for low-mass dark matter WIMPs with 12 ton-day exposure of DarkSide-50

We report on the search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 10 GeV/c2, from the analysis of the entire dataset acquired with a low-radioactivity argon target by the DarkSide-50 experiment at Laboratori Nazionali del Gran Sasso. The new analysis benefits from more accurate calibration of the detector response, improved background model, and better determination of systematic uncertainties, allowing us to accurately model the background rate and spectra down to 0.06 keVer. A 90% C.L. exclusion limit for the spin-independent cross section of 3 GeV/c2 mass WIMP on nucleons is set at 6×10−43 cm2, about a factor 10 better than the previous DarkSide-50 limit. This analysis extends the exclusion region for spin-independent dark matter interactions below the current experimental constraints in the [1.2, 3.6] GeV/c2 WIMP mass range.5 MoreReceived 28 July 2022Accepted 6 January 2023DOI:https://doi.org/10.1103/PhysRevD.107.063001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDark matterParticle dark matterPhysical SystemsWeakly interacting massive particlesTechniquesDark matter detectorsParticle detectorsParticles & FieldsNuclear PhysicsGravitation, Cosmology & Astrophysics

WIMPy leptogenesis in non-standard cosmologies

We study the possibility of generating baryon asymmetry of the universe from dark matter (DM) annihilations during non-standard cosmological epochs. Considering the DM to be of weakly interacting massive particle (WIMP) type, the generation of baryon asymmetry via leptogenesis route is studied where WIMP DM annihilation produces a non-zero lepton asymmetry. Adopting a minimal particle physics model to realise this along with non-zero light neutrino masses, we consider three different types of non-standard cosmic history namely, (i) fast expanding universe, (ii) early matter domination and (iii) scalar-tensor theory of gravity. By solving the appropriate Boltzmann equations incorporating such non-standard history, we find that the allowed parameter space consistent with DM relic and observed baryon asymmetry gets enlarged with the possibility of lower DM mass in some scenarios. While such lighter DM can face further scrutiny at direct search experiments, the non-standard epochs offer complementary probes on their own.

Directional detection of dark matter using solid-state quantum sensing

Next-generation dark matter (DM) detectors searching for weakly interacting massive particles (WIMPs) will be sensitive to coherent scattering from solar neutrinos, demanding an efficient background-signal discrimination tool. Directional detectors improve sensitivity to WIMP DM despite the irreducible neutrino background. Wide-bandgap semiconductors offer a path to directional detection in a high-density target material. A detector of this type operates in a hybrid mode. The WIMP or neutrino-induced nuclear recoil is detected using real-time charge, phonon, or photon collection. The directional signal, however, is imprinted as a durable sub-micron damage track in the lattice structure. This directional signal can be read out by a variety of atomic physics techniques, from point defect quantum sensing to x-ray microscopy. In this Review, we present the detector principle as well as the status of the experimental techniques required for directional readout of nuclear recoil tracks. Specifically, we focus on diamond as a target material; it is both a leading platform for emerging quantum technologies and a promising component of next-generation semiconductor electronics. Based on the development and demonstration of directional readout in diamond over the next decade, a future WIMP detector will leverage or motivate advances in multiple disciplines toward precision dark matter and neutrino physics.

Primordial black hole dark matter in the presence of p-wave WIMP annihilation

We study the allowed primordial black hole (PBH) dark matter abundance in the mixed dark matter scenarios consisting of PBHs and self-annihilating weakly interacting massive particles (WIMPs) with a velocity dependent annihilation cross section. We first briefly illustrate how the WIMP dark matter halo profile changes for the velocity suppressed p-wave annihilation scenarios, compared with the familiar s-wave annihilation scenarios, and then discuss the PBH mass dependent upper bound on the allowed PBH dark matter abundance. The WIMPs can accrete onto a PBH to form an ultracompact minihalo with a spiky density profile. Such a spike is moderated in the central region of a halo because the WIMPs are annihilated away and this moderation is less effective for a smaller annihilation cross section. The WIMP core density becomes larger while the core radius becomes smaller for a velocity suppressed p-wave annihilation cross section than those for the s-wave annihilation scenarios. The annihilation cross section is dependent on the velocity which varies across the halo, and, in addition to the change of the WIMP density profile, another interesting feature is the PBH mass dependent bound on PBH dark matter abundance. This is in stark contrast to the s-wave annihilation scenarios where the PBH abundance bound is independent of the PBH mass. The allowed PBH dark matter fraction (with respect to the total dark matter abundance) is of order f PBH ≲ \U0001d4aa(10−7)(M⊙/MPBH)(−6+2γsp)/(3γsp+3) for the thermal relic p-wave dark matter with the mass 100 GeV where γsp is the slope index of the spike profile, to be compared with f PBH ≲ \U0001d4aa(10−9) for the corresponding thermal relic s-wave dark matter scenarios.

A new way to test the WIMP dark matter models

In this paper, we investigate the possibility of testing the weakly interacting massive particle (WIMP) dark matter (DM) models by applying the simplest phenomenological model which introduces an interaction term between dark energy (DE) and WIMP DM, i.e., Q = 3γDMHρDM. In general, the coupling strength γDE is close to 0 as the interaction between DE and WIMP DM is very weak, thus the effect of γDE on the evolution of Y associated with DM energy density can be safely neglected. Meanwhile, our numerical calculation also indicates that xf ≈ 20 is associated with DM freeze-out temperature, which is the same as the vanishing interaction scenario. As for DM relic density, it will be magnified by frac{2-3{upgamma}_{mathrm{DM}}}{2}{left[2pi {g}_{ast }{m}_{mathrm{DM}}^3/left(45{s}_0{x}_f^3right)right]}^{gamma_{mathrm{DM}}} times, which provides a new way to test WIMP DM models. As an example, we analyze the case in which WIMP DM is a scalar DM. (SGL+SNe+Hz) and (CMB+BAO+SNe) cosmological observations will give γDM = {0.134}_{-0.069}^{+0.17} and γDM = −0.0008 ± 0.0016, respectively. After further considering the constraints from DM direct detection experiment, DM indirect detection experiment, and DM relic density, we find that the allowed parameter space of the scalar DM model will be completely excluded for the former cosmological observations, while it will increase for the latter ones. Those two cosmological observations lead to an almost paradoxical conclusion. Therefore, one could expect more stringent constraints on the WMIP DM models, with the accumulation of more accurate cosmological observations in the near future.

A Dark Matter WIMP That Can Be Detected and Definitively Identified with Currently Planned Experiments

A recently proposed dark matter WIMP (weakly interacting massive particle) has only second-order couplings to gauge bosons and itself. As a result, it has small annihilation, scattering, and creation cross-sections, and is consequently consistent with all current experiments and the observed abundance of dark matter. These cross-sections are, however, still sufficiently large to enable detection in experiments that are planned for the near future, and definitive identification in experiments proposed on a longer time scale. The (multi-channel) cross-section for annihilation is consistent with thermal production and freeze-out in the early universe, and with current evidence for dark matter annihilation in analyses of the observations of gamma rays by Fermi-LAT and antiprotons by AMS-02, as well as the constraints from Planck and Fermi-LAT. The cross-section for direct detection via collision with xenon nuclei is estimated to be slightly below 10−47 cm2, which should be attainable by LZ and Xenon nT and well within the reach of Darwin. The cross-section for collider detection via vector boson fusion is estimated to be ∼1 fb, and may be ultimately attainable by the high-luminosity LHC; definitive collider identification will probably require the more powerful facilities now being proposed.

Superheavy WIMP dark matter from incomplete thermalization

Although it is usually thought that a class of weakly interacting massive particle (WIMP) dark matters (DMs), which have the vector coupling with the Z boson, is denied by null results of the direct DM searches, such WIMP DMs are still viable if they are superheavy with the mass of mDM≳109 GeV. In the future, the superheavy WIMP DMs can be searched up to mDM≃1012 GeV, which corresponds to the so-called neutrino floor limit. We show that the observed abundance of ΩDMh2≃0.1 for a superheavy WIMP DM can be reproduced by a suitable reheating temperature of TR≃mDM/29 after inflation, if the direct inflaton decay into DM is negligible or kinematically forbidden.

Black holes and WIMPs: all or nothing or something else

ABSTRACT We consider constraints on primordial black holes (PBHs) in the mass range $(10^{-18}\!-\!10^{15})\, \mathrm{M}_{\odot }$ if the dark matter (DM) comprises weakly interacting massive particles (WIMPs) that form haloes around them and generate γ-rays by annihilations. We first study the formation of the haloes and find that their density profile prior to WIMP annihilations evolves to a characteristic power-law form. Because of the wide range of PBH masses considered, our analysis forges an interesting link between previous approaches to this problem. We then consider the effect of the WIMP annihilations on the halo profile and the associated generation of γ-rays. The observed extragalactic γ-ray background implies that the PBH DM fraction is $f^{}_{\rm PBH} \lesssim 2 \times 10^{-9}\, (m_{\chi } / {\rm TeV})^{1.1}$ in the mass range $2 \times 10^{-12}\, \mathrm{M}_{\odot }\, (m_{\chi } / {\rm TeV})^{-3.2} \lesssim M \lesssim 5 \times 10^{12}\, \mathrm{M}_{\odot }\, (m_{\chi } / {\rm TeV})^{1.1}$, where mχ and M are the WIMP and PBH masses, respectively. This limit is independent of M and therefore applies for any PBH mass function. For $M \lesssim 2\times 10^{-12}\, \mathrm{M}_{\odot }\, (m_{\chi }/ {\rm TeV})^{-3.2}$, the constraint on $f^{}_{\rm PBH}$ is a decreasing function of M and PBHs could still make a significant DM contribution at very low masses. We also consider constraints on WIMPs if the DM is mostly PBHs. If the merging black holes recently discovered by LIGO/Virgo are of primordial origin, this would rule out the standard WIMP DM scenario. More generally, the WIMP DM fraction cannot exceed 10−4 for $M \gt 10^{-9}\, \mathrm{M}_{\odot }$ and $m_{\chi } \gt 10\,$ GeV. There is a region of parameter space, with $M \lesssim 10^{-11}\, \mathrm{M}_{\odot }$ and $m_{\chi } \lesssim 100\,$ GeV, in which WIMPs and PBHs can both provide some but not all of the DM, so that one requires a third DM candidate.

WIMPs at high energy muon colliders

The Weakly Interacting Massive Particle (WIMP) paradigm is one of the most compelling scenarios for particle dark matter (DM). We show in this paper that a high energy muon collider can make decisive statements about the WIMP DM, and this should serve as one of its main physics driver cases. We demonstrate this by employing the DM as the lightest member of an electroweak (EW) multiplet, which is a simple, yet one of the most challenging WIMP scenarios given its minimal collider signature and high thermal target mass scale of 1 TeV$-$23 TeV. We perform a first study of the reach of high energy muon colliders, focusing on the simple, inclusive and conservative signals with large missing mass, through the mono-photon, VBF di-muon and a novel mono-muon channel. Using these inclusive signals, it is possible to cover the thermal targets of doublet and triplet with a 10 TeV muon collider. Higher energies, 14 TeV$-$75 TeV, would ensure a $5 \sigma$ reach above the thermal targets for the higher EW multiplets. We also estimate the reach of a search for disappearing tracks, demonstrating the potential significant enhancement of the sensitivity.

Search for inelastic scattering of WIMP dark matter in XENON1T

We report the results of a search for the inelastic scattering of weakly interacting massive particles (WIMPs) in the XENON1T dark matter experiment. Scattering off $^{129}$Xe is the most sensitive probe of inelastic WIMP interactions, with a signature of a 39.6 keV de-excitation photon detected simultaneously with the nuclear recoil. Using an exposure of 0.89 tonne-years, we find no evidence of inelastic WIMP scattering with a significance of more than 2$\sigma$. A profile-likelihood ratio analysis is used to set upper limits on the cross-section of WIMP-nucleus interactions. We exclude new parameter space for WIMPs heavier than 100 GeV/c${}^2$, with the strongest upper limit of $3.3 \times 10^{-39}$ cm${}^2$ for 130 GeV/c${}^2$ WIMPs at 90\% confidence level.

The mass of a dark matter WIMP derived from the Hubble constant conflict

There continues to be good reason to believe that dark matter particles, which only “feel” the gravitational force, influence the local and distant Universe, despite drawing a complete blank in the search for such a particle. The expansion rate of the Universe is defined by the Hubble constant h. Measurements of the Hubble constant at different wavelengths produce different results, differing well beyond their errors. Here it is shown that the two precise but different values for the Hubble constant can be used to derive the mass of a weakly interacting massive particle (WIMP). An approximate mass of 1022 eV is determined with indications of why, so far, it has not been found and what is required to get positive confirmation of its presence. This result also indicates that the Hubble constant is the sum of more than one contribution with suggestions for experimental tests to determine, more precisely, the level of these contributions.

GW170817 constraints on the properties of a neutron star in the presence of WIMP dark matter

The properties of a neutron star are studied in the presence of dark matter. We have considered a relatively light weakly interacting massive particle (WIMP) as a dark matter candidate with properties suggested by the results of the DAMA/LIBRA collaboration, realized for instance within the framework of the Next-to-Minimal Supersymmetric Standard Model. The dark matter particle interacts with the baryonic matter of a neutron star through Higgs bosons. The dark matter variables are essentially fixed using the results of the DAMA/LIBRA experiment, which are then used to build the Lagrangian density for the WIMP–nucleon interaction inside a neutron star. We have used the effective field theory motivated relativistic mean field model to study the equations-of-state in the presence of dark matter. The predicted equations-of-state are used in the Tolman–Oppenheimer–Volkoff equations to obtain the mass–radius relations, the moment of inertia, and effects of the tidal field on a neutron star. The calculated properties are compared with the corresponding data of the GW170817 event.

Precise WIMP dark matter abundance and Standard Model thermodynamics

A weakly interacting massive particle (WIMP) is a leading candidate of the dark matter. The WIMP dark matter abundance is determined by the freeze-out mechanism. Once we know the property of the WIMP particle such as the mass and interaction, we can predict the dark matter abundance. There are, however, several uncertainties in the estimation of the WIMP dark matter abundance. In this work, we focus on the effect from Standard Model thermodynamics. We revisit the estimation of the WIMP dark matter abundance and its uncertainty due to the equation of state (EOS) in the Standard Model. We adopt the up-to-date estimate of the EOS of the Standard Model in the early Universe and find nearly 10% difference in the 1–1000 GeV dark matter abundance, compared to the conventional estimate of the EOS.

Bounds on WIMP dark matter from galaxy clusters at low redshift

Abstract In this work we study the cross-correlation between Fermi-LAT diffuse γ-ray maps and galaxy cluster catalogues in order to search for a diffuse dark matter signal. We employ an accurate estimation of the error covariance matrix and we select 4 galaxy cluster catalogues at low-redshift 0 < z < 0.2 with large-halo mass M500 > 1013M⊙ including infrared, optical and X-rays wavebands. We consider weakly interacting massive particle (WIMP) dark matter with 100% branching ratios into τ+τ−, $b\bar{b}$, W+W− and μ+μ−. No evidence for a WIMP dark matter signal is identified, and we derive competitive bounds. The WIMP thermally averaged cross section is excluded at 95% C.L. for dark matter masses below 20 GeV and annihilation in the τ+τ− channel.

SuperCDMS SNOLAB - Status and Plans

The Super Cryogenic Dark Matter Search (SuperCDMS) and its predecessor CDMS have been at the forefront of the search for Weakly Interacting Massive dark matter Particles (WIMPs) for close to two decades. Significant improvements in detector technology have opened up the low-mass parameter space (≲ 10 GeV/c2) where the experiment broke new ground with the CDMS low ionization threshold experiment (CDMSlite). Building on this success, SuperCDMS is preparing for the next phase of the experiment to be located at SNOLAB near Sudbury, Ontario. The new experimental setup will provide space for up to ∼200 kg of target mass in a considerably lower background environment. The initial payload of about 30 kg will be a mix of germanium and silicon targets in the form of both background discriminating iZIP and low-threshold HV detectors, pushing the sensitivity towards WIMPs with even lower masses and improving the cross-section reach of SuperCDMS by more than an order of magnitude. The long-term goal is to reach the neutrino-floor below 10 GeV/c2. We present the status of and plans for SuperCDMS at SNOLAB.

Energy response and position reconstruction in the DEAP-3600 dark matter experiment

DEAP-3600 is a dark matter WIMP (Weakly Interacting Massive Particles) search experiment, which aims to detect nuclear recoils from WIMP scattering in a liquid argon target. At WIMP masses of 100 GeV, DEAP-3600 has a projected sensitivity of 10−46 cm2 for the spin-independent elastic scattering cross section of WIMPs. The beta emissions from the intrinsic 39 Ar present in the natural Ar target, as well as external calibration sources, can be used to tune the energy calibration and position reconstruction in the energy region of interest (ROI) for WIMP signals. These proceedings will present the techniques used to determine the energy response and position reconstruction in DEAP-3600. Using these techniques, the light yield was found to be LY = (math) (fit syst.) ± 0.22(SPE syst.) PE/keVee with a fiducial mass for WIMP detection of 2 223 ± 74 kg for the first data set.

Low-Energy Physics Reach of Xenon Detectors for Nuclear-Recoil-Based Dark Matter and Neutrino Experiments.

Dual-phase xenon detectors lead the search for keV-scale nuclear recoil signals expected from the scattering of weakly interacting massive particle (WIMP) dark matter, and can potentially be used to study the coherent nuclear scattering of MeV-scale neutrinos. New capabilities of such experiments can be enabled by extending their nuclear recoil searches down to the lowest measurable energy. The response of the liquid xenon target medium to nuclear recoils, however, is not well characterized below a few keV, leading to large uncertainties in projected sensitivities. In this work, we report a new measurement of ionization signals from nuclear recoils in liquid xenon down to the lowest energy reported to date. At 0.3keV, we find that the average recoil produces approximately one ionization electron; this is the first measurement of nuclear recoil signals at the single-ionization-electron level, approaching the physical limit of liquid xenon ionization detectors. We discuss the implications of these measurements on the physics reach of xenon detectors for nuclear-recoil-based WIMP dark matter searches and the detection of coherent elastic neutrino-nucleus scattering.

Two-component dark matter with cogenesis of the baryon asymmetry of the Universe

We discuss the possibility of realising a two-component dark matter (DM) scenario where the two DM candidates differ from each other by virtue of their production mechanism in the early universe. One of the DM candidates is thermally generated in a way similar to the weakly interacting massive particle (WIMP) paradigm where the DM abundance is governed by its freeze-out while the other candidate is produced only from non-thermal contributions similar to freeze-in mechanism. We discuss this in a minimal extension of the standard model where light neutrino masses arise radiatively in a way similar to the scotogenic models with DM particles going inside the loop. The lepton asymmetry is generated at the same time from WIMP DM annihilations as well as partially from the mother particle for non-thermal DM. This can be achieved while satisfying the relevant experimental bounds, and keeping the scale of leptogenesis or the thermal DM mass as low as 3 TeV, well within present experimental reach. In contrast to the TeV scale thermal DM mass, the non-thermal DM can be as low as a few keV, giving rise to the possibility of a sub-dominant warm dark matter (WDM) component that can have interesting consequences on structure formation. The model also has tantalizing prospects of being detected at ongoing direct detection experiments as well as the ones looking for charged lepton flavour violating process like $\mu \rightarrow e \gamma$.