Direct Detection Searches Research Articles

Earth scattering of superheavy dark matter: Updated constraints from detectors old and new

Direct searches for Dark Matter (DM) are continuously improving, probing down to lower and lower DM-nucleon interaction cross sections. For strongly-interacting massive particle (SIMP) Dark Matter, however, the accessible cross section is bounded from above due to the stopping effect of the atmosphere, Earth and detector shielding. We present a careful calculation of the SIMP signal rate, focusing on super-heavy DM ($m_\chi \gtrsim 10^5 \,\,\mathrm{GeV}$) for which the standard nuclear-stopping formalism is applicable, and provide code for implementing this calculation numerically. With recent results from the low-threshold CRESST 2017 surface run, we improve the maximum cross section reach of direct detection searches by a factor of around 5000, for DM masses up to $10^8 \,\,\mathrm{GeV}$. A reanalysis of the longer-exposure, sub-surface CDMS-I results (published in 2002) improves the previous cross section reach by two orders of magnitude, for masses up to $10^{15} \,\,\mathrm{GeV}$. Along with complementary constraints from SIMP capture and annihilation in the Earth and Sun, these improved limits from direct nuclear scattering searches close a number of windows in the SIMP parameter space in the mass range $10^6$ GeV to $10^{13}$ GeV, of particular interest for heavy DM produced gravitationally at the end of inflation.

Probing sub-GeV dark matter-baryon scattering with cosmological observables

We derive new limits on the elastic scattering cross-section between baryons and dark matter using Cosmic Microwave Background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form $\sigma\propto v^n$, where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-$\ell$ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of $\sim$MeV. We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches.

Hidden U(1) gauge symmetry realizing a neutrinophilic two-Higgs-doublet model with dark matter

We propose a neutrinophilic two-Higgs-doublet model with hidden local $U(1)$ symmetry, where active neutrinos are Dirac type, and a fermionic dark matter (DM) candidate is naturally induced as a result of remnant symmetry even after the spontaneous symmetry breaking. In addition, a physical Goldstone boson arises as a consequence of two types of gauge singlet bosons and contributes to the DM phenomenologies as well as an additional neutral gauge boson. Then, we analyze the relic density of DM within the safe range of direct detection searches and show the allowed region of dark matter mass.

Neutrino non-standard interactions and dark matter searches with multi-ton scale detectors

Future dark matter (DM) direct detection searches will be subject to irreducible neutrino backgrounds that will challenge the identification of an actual WIMP signal in experiments without directionality sensitivity. We study the impact of neutrino-quark non-standard interactions (NSI) on this background, assuming the constraints from neutrino oscillations and the recent COHERENT experiment data, which are relevant for NSI mediated by light mediators, {m}_{mathrm{med}}lesssim mathcal{O}left(mathrm{GeV}right) . We calculate the expected number of neutrino-nucleus elastic scattering events in a Xe-based ton-size dark matter detector, including solar neutrino fluxes from the pp chain and CNO cycle as well as sub-GeV atmospheric fluxes and taking into account NSI effects in both propagation and detection. We find that sizable deviations from the standard model expectation are possible, but are more pronounced for flavor-diagonal couplings, in particular for electron neutrinos. We show that neutrino NSI can enhance or deplete the neutrino-nucleus event rate, which may impact DM searches in multi-ton detectors.

MeV dark matter complementarity and the dark photon portal

We discuss the phenomenology of an MeV-scale Dirac fermion coupled to the Standard Model through a dark photon with kinetic mixing with the electromagnetic field. We compute the dark matter relic density and explore the interplay of direct detection and accelerator searches for dark photons. We show that precise measurements of the temperature and polarization power spectra of the Cosmic Microwave Background Radiation lead to stringent constraints, leaving a small window for the thermal production of this MeV dark matter candidate. The forthcoming MeV gamma-ray telescope e-ASTROGAM will offer important and complementary opportunities to discover dark matter particles with masses below ∼ 10 MeV . Lastly, we discuss how a late-time inflation episode and freeze-in production could conspire to yield the correct relic density while being consistent with existing and future constraints.

Model-independent analysis of the DAMPE excess

The Dark Matter Particle Explorer (DAMPE) recently released measurements of the electron spectrum with a hint of a narrow peak at about 1.4 TeV. We investigate dark matter (DM) models that could produce such a signal by annihilation in a nearby subhalo whilst simultaneously satisfying constraints from DM searches. In our model-independent approach, we consider all renormalizable interactions via a spin 0 or 1 mediator between spin 0 or 1/2 DM particles and the Standard Model leptons. We find that of the 20 combinations, 10 are ruled out by velocity or helicity suppression of the annihilation cross section to fermions. The remaining 10 models, though, evade constraints from the relic density, collider and direct detection searches, and include models of spin 0 and 1/2 DM coupling to a spin 0 or 1 mediator. We delineate the regions of mediator mass and couplings that could explain the DAMPE excess. In all cases the mediator is required to be heaver than about 2 TeV by LEP limits.

Looking for the WIMP next door

We comprehensively study experimental constraints and prospects for a class of minimal hidden sector dark matter (DM) models, highlighting how the cosmological history of these models informs the experimental signals. We study simple ‘secluded’ models, where the DM freezes out into unstable dark mediator states, and consider the minimal cosmic history of this dark sector, where coupling of the dark mediator to the SM was sufficient to keep the two sectors in thermal equilibrium at early times. In the well-motivated case where the dark mediators couple to the Standard Model (SM) via renormalizable interactions, the requirement of thermal equilibrium provides a minimal, UV-insensitive, and predictive cosmology for hidden sector dark matter. We call DM that freezes out of a dark radiation bath in thermal equilibrium with the SM a WIMP next door, and demonstrate that the parameter space for such WIMPs next door is sharply defined, bounded, and in large part potentially accessible. This parameter space, and the corresponding signals, depend on the leading interaction between the SM and the dark mediator; we establish it for both Higgs and vector portal interactions. In particular, there is a cosmological lower bound on the portal coupling strength necessary to thermalize the two sectors in the early universe. We determine this thermalization floor as a function of equilibration temperature for the first time. We demonstrate that direct detection experiments are currently probing this cosmological lower bound in some regions of parameter space, while indirect detection signals and terrestrial searches for the mediator cut further into the viable parameter space. We present regions of interest for both direct detection and dark mediator searches, including motivated parameter space for the direct detection of sub-GeV DM.

Z′ portal to Chern-Simons Dark Matter

We study the phenomenological credibility of a vectorial dark matter, coupled to a Z′ portal through Chern-Simons interaction. We scrutinize two possibilities of connecting a Z′ with the Standard Model: (1) through kinetic mixing and (2) from a second Chern-Simons interaction. Both scenarios are characterized by suppressed nuclear recoil scatterings, rendering direct detection searches not promising. Indirect detection experiments, on the other hand, furnish complementary limits for TeV scale masses, specially with the CTA. Searches for mono-jet and dileptons signals at the LHC are important to partially probe the kinetic mixing setup. Finally we propose an UV completion of the Chern-Simons Dark Matter framework.

The semi-Hooperon: Gamma-ray and anti-proton excesses in the Galactic Center

A puzzling excess in gamma-rays at GeV energies has been observed in the center of our galaxy using Fermi-LAT data. Its origin is still unknown, but it is well fitted by Weakly Interacting Massive Particles (WIMPs) annihilations into quarks with a cross section around 10−26 cm3s−1 with masses of 20–50 GeV, scenario which is promptly revisited. An excess favoring similar WIMP properties has also been seen in anti-protons with AMS-02 data potentially coming from the Galactic Center as well. In this work, we explore the possibility of fitting these excesses in terms of semi-annihilating dark matter, dubbed as semi-Hooperon, with the process WIMPWIMP→WIMPX being responsible for the gamma-ray excess, where X=h,Z. An interesting feature of semi-annihilations is the change in the relic density prediction compared to the standard case, and the possibility to alleviate stringent limits stemming from direct detection searches. Moreover, we discuss which models might give rise to a successful semi-Hooperon setup in the context of Z3,Z4 and extra “dark” gauge symmetries.

Advances in Bolometer Technology for Fundamental Physics

In the last decade, cryogenic bolometers have provided increasingly improved resolution and sensitivity in particle and radiation detectors. Thermal particle detectors have proven their outstanding capabilities in different fields of fundamental physics, especially in rare event detection. Cryogenic incoherent detector arrays designed to detect millimeter-wave photons have helped enable precision measurements of anisotropies in the cosmic microwave background (CMB), providing a unique probe of early universe physics and helping to constrain parameters of particle physics such as the sum of the neutrino masses. We review the latest achievements of cryogenic particle detectors for direct detection searches for dark matter and double-[Formula: see text] decay, as well as for CMB measurements, and we discuss expected improvements aiming to increase the sensitivities of these experiments. An important challenge is the large-scale implementation of arrays of detectors such as transition edge sensors, especially in CMB polarization experiments. We describe the challenges of scaling up to these larger arrays, including fabrication throughput and development of new multiplexing electronics.

Thermal dark matter via the flavon portal

Dark matter (DM) is added to the Froggatt-Nielsen (FN) mechanism, and conditions for its successful freezeout identified. Requesting the FN scale $\Lambda_{\text{FN}}$ to be the cutoff of the theory renders freezeout scenarios surprisingly few. Fermionic DM is typically charged under $U(1)_{\text{FN}}$, with the dominant annihilation channel a CP-even flavon + CP-odd flavon. A minimal case is when the DM-flavon coupling strength is $\mathcal{O}(1)$, with several implications: (1) the DM mass is $\mathcal{O}$(100 GeV - 1 TeV), thanks to the WIMP coincidence, (2) requiring perturbativity of couplings puts a lower $and$ upper limit on the flavor scale, 2 TeV $\lesssim \Lambda_{\text{FN}} \lesssim 14~$TeV, on account of its relation to DM mass and couplings, (3) DM is a "secluded WIMP" effectively hidden from collider and direct detection searches. Limits on the masses of dark matter and mediators from kaon mixing measurements constitute the best constraints, surpassing Xenon1T, Fermi-LAT, and the LHC. Future direct detection searches, and collider searches for missing energy plus a single jet/bottom/top, are promising avenues for discovery.

Dark Matter and the elusive Z\u2032 in a dynamical Inverse Seesaw scenario

The Inverse Seesaw naturally explains the smallness of neutrino masses via an approximate B − L symmetry broken only by a correspondingly small parameter. In this work the possible dynamical generation of the Inverse Seesaw neutrino mass mechanism from the spontaneous breaking of a gauged U(1) B − L symmetry is investigated. Interestingly, the Inverse Seesaw pattern requires a chiral content such that anomaly cancellation predicts the existence of extra fermions belonging to a dark sector with large, non-trivial, charges under the U(1) B − L. We investigate the phenomenology associated to these new states and find that one of them is a viable dark matter candidate with mass around the TeV scale, whose interaction with the Standard Model is mediated by the Z′ boson associated to the gauged U(1) B − L symmetry. Given the large charges required for anomaly cancellation in the dark sector, the B − LZ′ interacts preferentially with this dark sector rather than with the Standard Model. This suppresses the rate at direct detection searches and thus alleviates the constraints on Z′-mediated dark matter relic abundance. The collider phenomenology of this elusive Z′ is also discussed.

Constraining the parameter space of branon dark matter using white dwarf stars

In the present work we study the branon dark matter particles impact on compact objects, and we provide the first constraints of the parameter space using white dwarf stars. The branon dark matter model is characterized by two free parameters, namely the branon mass particle M and the brane tension factor $f$. The latter determines the strength of the interaction of branon dark matter particles with baryons. By considering a typical white dwarf star we were able to obtain constraints on branon dark matter and compare with current limits obtained by direct detection searches and dark matter abundance. In particular our results show that i) for heavy branons with a mass $M > 10 GeV$ white dwarfs fail to provide us with bounds better than current limits from DM direct detection searches, and ii) for light branons in the mass range $2 keV < M < 1 GeV$, which cannot be probed neither with current dark matter experiments nor with the next generation of detectors, the dark matter abundance constrain determines $f$ as a function of $M$ in the range $0.1 GeV < M < 1 GeV$ for the branon mass and $1 GeV < f < 5 GeV$ for the brane tension factor. Furthermore, our findings indicate that the limits from white dwarfs are not stronger than the dark matter abundance constrain.

Constraining the scalar singlet and inert dark matter models using neutron stars

We study the scalar singlet as well as the two-Higgs doublet model inert dark matter particles' impact on compact objects, and we provide the first constraints of the parameter space using neutron stars. The models discussed here are characterized by two free parameters, namely the mass ${M}_{\ensuremath{\chi}}$ of the scalar particle that plays the role of the dark matter in the Universe, and a dimensionless coupling constant ${\ensuremath{\lambda}}_{\ensuremath{\chi}}$ that determines the strength of the interaction of the dark matter particles with the Standard Model Higgs boson. By considering a typical neutron star we are able to obtain constraints on scalar dark matter depending on the dark matter (DM) annihilation cross section and self-interaction coupling constant. Our findings show that (i) for heavy DM particles neutron stars can provide us with bounds better that the current limits from direct detection searches only when the self-annihilations of DM particles are negligible and the DM self-interaction coupling constant is very small, while (ii) for light DM particles the bounds obtained here are comparable to limits from Higgs invisible decays unless the DM particles are extremely light.

Superparticle phenomenology from the natural mini-landscape

The methodology of the heterotic mini-landscape attempts to zero in on phenomenologically viable corners of the string landscape where the effective low energy theory is the Minimal Supersymmetric Standard Model with localized grand unification. The gaugino mass pattern is that of mirage-mediation. The magnitudes of various SM Yukawa couplings point to a picture where scalar soft SUSY breaking terms are related to the geography of fields in the compactified dimensions. Higgs fields and third generation scalars extend to the bulk and occur in split multiplets with TeV scale soft masses. First and second generation scalars, localized at orbifold fixed points or tori with enhanced symmetry, occur in complete GUT multiplets and have much larger masses. This picture can be matched onto the parameter space of generalized mirage mediation. Naturalness considerations, the requirement of the observed electroweak symmetry breaking pattern, and LHC bounds on mg together limit the gravitino mass to the m3/2 ∼ 5-60 TeV range. The mirage unification scale is bounded from below with the limit depending on the ratio of squark to gravitino masses. We show that while natural SUSY in this realization may escape detection even at the high luminosity LHC, the high energy LHC with sqrt{s}=33 TeV could unequivocally confirm or exclude this scenario. It should be possible to detect the expected light higgsinos at the ILC if these are kinematically accessible, and possibly also discriminate the expected compression of gaugino masses in the natural mini-landscape picture from the mass pattern expected in models with gaugino mass unification. The thermal WIMP signal should be accessible via direct detection searches at the multi-ton noble liquid detectors such as XENONnT or LZ.

Dark matter and exotic neutrino interactions in direct detection searches

We investigate the effect of new physics interacting with both Dark Matter (DM) and neutrinos at DM direct detection experiments. Working within a simplified model formalism, we consider vector and scalar mediators to determine the scattering of DM as well as the modified scattering of solar neutrinos off nuclei. Using existing data from LUX as well as the expected sensitivity of LUX-ZEPLIN and DARWIN, we set limit on the couplings of the mediators to quarks, neutrinos and DM. Given the current limits, we also assess the true DM discovery potential of direct detection experiments under the presence of exotic neutrino interactions. In the case of a vector mediator, we show that the DM discovery reach of future experiments is affected for DM masses mχ ≲ 10 GeV or DM scattering cross sections σχ ≲ 10−47 cm2. On the other hand, a scalar mediator will not affect the discovery reach appreciably.

Isospin-violating dark matter in the light of recent data

In scenarios where the dark matter interacts differently with protons and neutrons (isospin-violating dark matter), the interpretation of the experimental limits on the dark matter spin-independent cross section may be significantly modified. On the one hand, the direct detection constraints are shifted depending on the target nucleus, possibly changing the hierarchy among different experiments. On the other hand, the relative strength between the bounds from neutrino detectors and those from direct detection experiments is altered, allowing the former to be more competitive. In this paper, the status of isospin-violating dark matter is assessed in the light of recent data, and the prospects for its detection in the near future are analyzed. We find, for example, that there are regions in the parameter space where IceCube currently provides the most stringent limits on the spin-independent cross section, or others where the expected sensitivity of DEAP-3600 is well above the LUX exclusion limit. Our results highlight the complementarity among different targets in direct detection experiments, and between direct detection and neutrino searches in the quest for a dark matter signal.

Likelihood analysis of supersymmetric SU(5) GUTs

We perform a likelihood analysis of the constraints from accelerator experiments and astrophysical observations on supersymmetric (SUSY) models with SU(5) boundary conditions on soft SUSY-breaking parameters at the GUT scale. The parameter space of the models studied has seven parameters: a universal gaugino mass m_{1/2}, distinct masses for the scalar partners of matter fermions in five- and ten-dimensional representations of SU(5), m_5 and m_{10}, and for the mathbf {5} and {bar{mathbf{5}}} Higgs representations m_{H_u} and m_{H_d}, a universal trilinear soft SUSY-breaking parameter A_0, and the ratio of Higgs vevs tan beta . In addition to previous constraints from direct sparticle searches, low-energy and flavour observables, we incorporate constraints based on preliminary results from 13 TeV LHC searches for jets + events and long-lived particles, as well as the latest PandaX-II and LUX searches for direct Dark Matter detection. In addition to previously identified mechanisms for bringing the supersymmetric relic density into the range allowed by cosmology, we identify a novel {tilde{u}_R}/{tilde{c}_R} - tilde{chi }^{0}_{1} coannihilation mechanism that appears in the supersymmetric SU(5) GUT model and discuss the role of {{tilde{nu }}_tau } coannihilation. We find complementarity between the prospects for direct Dark Matter detection and SUSY searches at the LHC.

Asteroseismic constraints on asymmetric dark matter: Light particles with an effective spin-dependent coupling

So far, direct detection searches have come empty handed in their quest for Dark Matter (DM). Meanwhile, asteroseismology arises as a complementary tool to study DM, as its accumulation in a star can enhance energy transport, by providing a conduction mechanism, producing significant changes in the stellar structure during the course of the star's evolution. The stellar core, particularly affected by the presence of DM, can be investigated through precise asteroseismic diagnostics. We modelled three stars including DM energy transport: the Sun, a slightly less massive and much older star, KIC 7871531 ($0.85 \, M_{\odot}$, $9.41 \, \text{Gyr}$), and a more massive and younger one, KIC 8379927 ($1.12 \, M_{\odot}$, $1.82 \, \text{Gyr}$). We considered both the case of Weakly Interactive Massive Particles, albeit with a low annihilation, and the case of Asymmetric DM for which the number of trapped particles in the star can be much greater. By analysing these models with asteroseismic separation ratios weighted towards the core, we found indications limiting the effective spin-dependent DM-proton coupling for masses of a few GeV. This independent result is very close to the most recent and most stringent direct detection DM constraints.

Radiative neutrino model with SU(2)L triplet fields

We propose a loop-induced neutrino mass model, in which we introduce several exotic fermions and bosons with an $SU(2{)}_{L}$ multiplet, and discuss various phenomenologies such as lepton flavor violations, the muon anomalous magnetic moment, nonstandard interacting neutrinoless double beta decay, the relic density of dark matter, and the possibility of the spin-independent direct detection searches, imposing the constraints of oblique parameters. And we show a benchmark point to satisfy all the constraints and discuss our predictions.