Range Of Dark Matter Masses Research Articles

Indirect Detection for Higgs Portal Majorana Fermionic Dark Matter

Abstract We study the $\gamma$-ray signal emitted from dark matter (DM) pair annihilation in the Higgs portal Majorana fermion DM model. In the model, a Majorana fermion DM $\chi$ couples with the Standard Model (SM) Higgs field $H$ through a higher-dimensional term $-{\cal L}\supset H^\dagger H \bar{\chi }\chi /\Lambda$, where $\Lambda$ is a cutoff scale [1]. The pair annihilation of $\chi$ through the above term produces the Higgs boson and the longitudinal modes of $W,Z$ gauge bosons. The Milky Way dwarf spheroidal satellite galaxies (dSphs) are used as the most promising targets to search for the $\gamma$-ray signal of the model, due to high DM density and lack of astrophysical backgrounds. The Fermi Large Area Telescope (Fermi-LAT) is used for the search, for its high sensitivity [2]. In this work, we use 14-year Fermi-LAT data from 16 dSphs, to constrain the DM pair annihilation cross section for the DM mass range from 125 GeV to 100 TeV.

Constraining bosonic dark matter-baryon interactions from neutron star collapse

Dark matter (DM) may be captured around a neutron star (NS) through DM-nucleon interactions. We observe that the enhancement of such capturing is particularly significant when DM-nucleon scattering cross-section depends on the relative velocity and/or momentum transfer. This increment could potentially lead to the formation of a black hole within the typical lifetime of the NS. As the black hole grows through the accretion of matter from the NS, it ultimately results in the collapse of the host. Utilizing the existing pulsar data J0437-4715 and J2124-3858, we derive the stringent constraints on the DM-nucleon scattering cross-section across a broad range of DM masses.

Sensitivity to sub-GeV dark matter from cosmic-ray scattering with very-high-energy gamma-ray observatories

Huge efforts have been deployed to detect dark matter (DM) in the GeV-TeV mass range involving various detection techniques, and led to strong constraints in the available parameter space. We compute here the sensitivity to sub-GeV DM that can be probed from the inevitable cosmic-ray scattering onto DM particles populating the Milky Way halo. Inelastic scattering of energetic cosmic rays off DM would produce high-energy gamma rays in the final state, providing a new avenue to probe the poorly-constrained so far sub-GeV dark matter mass range. In this work we derivesensitivity forecasts for the inelastic cosmic-ray proton-DM cross section for current and future very-high-energy gamma-ray observatories such as H.E.S.S., LHAASO, CTA and SWGO in the 100 eV to 100 MeV mass range. These inelastic cross section constraints are converted to the elastic proton-DM cross sectionto highlight further complementarity with cosmological, collider and direct detection searches.The sensitivity computed at 95% confidence level on the elastic cross section reaches ∼2 × 10-32 cm2 for a 100 keV DM mass for H.E.S.S.-like and ∼7 × 10-34 cm2 for a ∼1 keV DM mass for LHAASO. The sensitivity prospects for CTA and a strawman SWGO model reach ∼6 × 10-34 cm2 and ∼4 × 10-35 cm2, for DM masses of 10 keV and 1 keV, respectively. The sensitivity reach of the gamma-ray observatories considered here enables to probe an uncharted region of the DM mass-cross section parameter space.

Importance of Cosmic-Ray Propagation on Sub-GeV Dark Matter Constraints

We study sub-GeV dark matter (DM) particles that may annihilate or decay into Standard Model particles producing an exotic injection component in the Milky Way that leaves an imprint in both photon and cosmic-ray (CR) fluxes. Specifically, the DM particles may annihilate or decay into e + e −, μ + μ −, or π + π − and may radiate photons through their e ± products. The resulting e ± products can be directly observed in probes such as Voyager 1. Alternatively, the e ± products may produce bremsstrahlung radiation and upscatter the low-energy Galactic photon fields via the inverse Compton process, generating a broad emission from X-ray to γ-ray energies observable in experiments such as XMM-Newton. We find that we get a significant improvement in the DM annihilation and decay constraints from XMM-Newton (excluding thermally averaged cross sections of 10−31 cm3 s−1 ≲ 〈σ v〉 ≲ 10−26 cm3 s−1 and decay lifetimes of 1026 s ≲ τ ≲ 1028 s, respectively) by including best-fit CR propagation and diffusion parameters. This yields the strongest astrophysical constraints for this mass range of DM of 1 MeV to a few GeV and even surpasses cosmological bounds across a wide range of masses as well.

Hunting for hypercharge anapole dark matter in all spin scenarios

We conduct a combined analysis to investigate dark matter (DM) with hypercharge anapole moments, focusing on scenarios where Majorana DM particles with spin 1/2, 1, 3/2, and 2 interact exclusively with Standard Model particles through U(1)Y hypercharge anapole terms for the first time. For completeness, we construct general effective U(1) gauge-invariant three-point vertices. These enable the generation of hypercharge gauge-invariant interaction vertices for both a virtual photon γ and a virtual Z boson with two identical massive Majorana particles of any nonzero spin s, after the spontaneous breaking of electroweak gauge symmetry. For complementarity, we adopt effective operators tailored to each dark matter spin allowing crossing symmetry. We calculate the relic abundance, analyze current constraints and future sensitivities from dark matter direct detection and collider experiments, and apply the conceptual naive perturbativity bound. Our estimations based on a generalized vertex calculation demonstrate that the scenario with a higher-spin DM is more stringently constrained than a lower-spin DM, primarily due to the reduced annihilation cross section and/or the enhanced rate of LHC monojet events. As a remarkable outcome, the spin-2 anapole DM scenario is almost entirely excluded, while the high-luminosity LHC exhibits high sensitivities in probing spin-1 and -3/2 scenarios, except for a tiny parameter range of DM mass around 1 TeV. A significant portion of the remaining parameter space in the spin-1/2 DM scenario can be explored through upcoming Xenon experiments, with more than 20 ton-yr exposure equivalent to approximately 5 years of running the XENONnT experiment. Published by the American Physical Society 2024

Milky Way white dwarfs as sub-GeV to multi-TeV dark matter detectors

We show that Milky Way white dwarfs are excellent targets for dark matter (DM) detection. Using Fermi and H.E.S.S. Galactic center gamma-ray data, we investigate sensitivity to DM annihilating within white dwarfs into long-lived or boosted mediators and producing detectable gamma rays. Depending on the Galactic DM distribution, we set new constraints on the spin-independent scattering cross section down to 10-45-10-41 cm2 in the sub-GeV DM mass range, which is multiple orders of magnitude stronger than existing limits. For a generalized NFW DM profile, we find that our white dwarf constraints exceed spin-independent direct detection limits across most of the sub-GeV to multi-TeV DM mass range, achieving sensitivities as low as about 10-46 cm2. In addition, we improve earlier versions of the DM capture calculation in white dwarfs, by including the low-temperature distribution of nuclei when the white dwarf approaches crystallization. This yields smaller capture rates than previously calculated by a factor of a few up to two orders of magnitude, depending on white dwarf size and the astrophysical system.

Gravitational dark matter from minimal preheating

Following our previous work, we continue to explore gravitational dark matter production during the minimal preheating caused by inflaton self-resonance. In this situation there is only one dimensionless index parameter n characterizing the inflation potential after the end of inflation, which leads to a robust prediction on the gravitational dark matter relic abundance. Using lattice method to handle the non-perturbative evolutions of relevant quantities during the inflaton self-resonance, we derive the gravitational dark matter relic abundance arising from both the inflaton condensate and fluctuation annihilation. While being absent in the large gravitational dark matter mass range for n = 2, the former one can instead dominate over the later one for n = 4, 6. Our results show that gravitational dark matter mass of 1.04 (2.66) × 1014 GeV accommodates the observed value of dark matter relic abundance for n = 4 (6).

Primordial black hole versus inflaton

We compare the dark matter (DM) production processes and its parameters space in the background of reheating obtained from two chief systems in the early Universe: the inflaton ϕ and the primordial black holes (PBHs). We concentrated on the mechanism where DMs are universally produced only from the PBH decay and the generation of the standard model plasma from both inflaton and PBHs. Whereas the distribution of primordial black holes behaves like dust, the inflaton phenomenology depends strongly on its equation of state after the inflationary phase, which in turn is conditioned by the nature of the potential V(ϕ). Depending upon the initial mass and population of PBHs, a large range of DM mass is shown to be viable if reheating is controlled by PBHs itself. Inflaton-dominated reheating is observed to further widen such possibilities depending on the initial population of black holes and its mass as well as the coupling of the inflaton to the standard model sector. Published by the American Physical Society 2024

Minimal model of fermion FIMP dark matter

We investigate a simple extension of the standard model in which the dark matter consists of a feebly interacting fermion, charged under a new Z4 symmetry, that is produced in the early Universe by the freeze-in mechanism. The only other new particle included in the model is a singlet scalar, also charged under the Z4, which couples to the fermion via Yukawa interactions and to the standard model Higgs. The model is truly minimal, as it admits just five free parameters: two masses and three dimensionless couplings. Depending on their values, the freeze-in mechanism can be realized in different ways, each characterized by its own production processes. For all of them, we numerically study the relic density as a function of the free parameters of the model and determine the regions consistent with the dark matter constraint. Our results show that this scenario is viable over a wide range of couplings and dark matter masses. This model, therefore, not only offers a novel solution to the dark matter problem, but it also provides a minimal realization of freeze-in for fermion dark matter. Published by the American Physical Society 2024

Sterile neutrinos from dark matter: a ν nightmare?

We provide a comprehensive study of observable spectra from dark matter pair-annihilation or decay into sterile (right-handed) neutrinos. This occurs, for instance, in neutrino portal dark matter models, where a sterile neutrino acts as the portal between dark matter and the Standard Model sector. The subsequent decays of right-handed neutrinos produce detectable Standard Model particles, notably photons, positrons, and neutrinos. We study the phenomenology of models where the right-handed neutrino masses are below the GeV scale, as well as models where they are at, or significantly heavier than, the TeV scale. In both instances, and for different reasons, the standard tools, including Monte Carlo simulations, are both inadequate and inaccurate. We present the complete framework to compute the relevant branching ratios for right-handed neutrino decays and the spectra of secondary photons, positrons, and neutrinos for a broad range of dark matter and right-handed neutrino masses. We discuss the general features of such signals, and compare the spectra to standard signals from dark matter annihilation/decay into bottom quarks. Additionally, we provide open source code (The code is available at https://github.com/LoganAMorrison/blackthorn) that can be used to compute such spectra.

Freeze-in dark matter in EDGES 21-cm signal* *Supported in part by the National Natural Science Foundation of China (11775039), the High-level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University (ZKNUC2021006), and the Natural Science Foundation of Henan Province, China(232300421358)

The first measurement of the temperature of the hydrogen 21-cm signal reported by EDGES strongly favors the Coulomb-like interaction between freeze-in dark matter and baryon fluid. We investigate such dark matter in both the one- and two-component context with the light force carrier(s) essential for the Coulomb-like interaction being other than photons. Using a conversion of cross sections used by relevant experiments and Boltzmann equations to encode the effects of the dark matter-baryon interaction, we show that both cases are robustly excluded by the stringent stellar cooling bounds in the sub-GeV dark matter mass range. The exclusion of the one-component case applies to simplified freeze-in dark matter with the light force carrier as dark photons, gauged , ,, or axion-like particles, whereas the exclusion of the two-component case applies to simplified freeze-in dark matter with the two light force carriers as two axion-like particles coupled to standard model quarks and leptons.

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.

Warm dark matter from a gravitational freeze-in in extra dimensions

We study the freeze-in of gravitationally interacting dark matter in extra dimensions. Focusing on a minimal dark matter candidate that only interacts with the SM via gravity in a five-dimensional model we find that a large range of dark matter and Kaluza-Klein graviton masses can lead to the observed relic density. The preferred values of the masses and the strength of the interaction make this scenario very hard to test in terrestrial experiments. However, significant parts of the parameter space lead to warm dark matter and can be tested by cosmological and astrophysical observations.

Impact of ATLAS constraints on effective dark matter-standard model interactions with spin-one mediators

We complement a previous work [Fabiola Fortuna et al., Effective field theory analysis of dark matter-standard model interactions with spin one mediators, J. High Energy Phys. 02 (2021) 223.] using an effective field theory framework of dark matter and standard model interactions, with spin-one mediators, exploring a wider dark matter mass range, up to 6.4 TeV. We again use bounds from different experiments: relic density, direct detection experiments, and indirect detection limits from the search of gamma-ray emissions and positron fluxes. Additionally, in this paper we add collider constraints by the ATLAS Collaboration in the monojet analysis. Moreover, here we tested our previous results in the light of the aforementioned ATLAS data, which turns out to be the most restrictive for light dark matter masses (as expected), ${m}_{\mathrm{DM}}<{M}_{Z}/2$. We obtain a larger range of solutions for the operators of dimension 5, OP1 and OP4, where masses above 43 GeV and 30 GeV [except for the $Z$-resonance region, $\ensuremath{\sim}({M}_{Z}\ifmmode\pm\else\textpm\fi{}{\mathrm{\ensuremath{\Gamma}}}_{Z})/2$], respectively, are allowed. In contrast, the operator of dimension 6, OP3, has viable solutions for masses $\ensuremath{\gtrsim}190\text{ }\text{ }\mathrm{GeV}$. For the combination of OP1 and OP3 we obtain solutions (for masses larger than 140 GeV or 325 GeV) that depend on the relative sign between the operators.

The Z7 model of three-component scalar dark matter

We investigate, for the first time, a scenario where the dark matter consists of three complex scalar fields that are stabilized by a single Z7 symmetry. As an extension of the well-known scalar Higgs-portal, this Z7 model is also subject to important restrictions arising from the relic density constraint and from direct detection experiments. Our goal in this paper is to find and characterize the viable regions of this model, and to analyze its detection prospects in future experiments. First, the processes that affect the relic densities are identified (they include semiannihilations and conversions) and then incorporated into the Boltzmann equations for the dark matter abundances, which are numerically solved with micrOMEGAs. By means of random scans of the parameter space, the regions consistent with current data, including the recent direct detection limit from the LZ experiment, are selected. Our results reveal that the Z7 model is indeed viable over a wide range of dark matter masses and that both conversions and semiannihilations play an important role in determining the relic densities. Remarkably, we find that in many cases all three of the dark matter particles give rise to observable signals in future direct detection experiments, providing a suitable way to test this scenario.

Ultraviolet freeze-in dark matter through the dilaton portal

We study a class of models in which the Standard Model (SM) and dark matter (DM) belong to a conformal/scale-invariant theory at high energies. Scale invariance is spontaneously broken at scale $f$, giving rise to a dilaton as the corresponding Goldstone boson. In the low-energy theory, we assume that DM interacts with the SM solely through the dilaton portal, which is suppressed by the conformal breaking scale $f$. For $f\ensuremath{\gg}\mathrm{TeV}$, the portal interactions are extremely weak, resulting in DM not being in thermal equilibrium with the SM. Thus, ultraviolet freeze-in production of DM occurs through the dilaton portal, being most effective at the maximum temperature of the SM bath. The temperature evolution is greatly impacted by the reheating dynamics, which we parametrize using a general equation of state $w$ and temperature at the end of reheating ${T}_{\mathrm{rh}}$. We analyze the implications of the reheating dynamics for DM production in this framework and identify regions of parameter space that result in the observed DM relic abundance for a wide range of DM masses and reheating temperatures for scalar, vector, or fermion DM.

Fueling the search for light dark matter-electron scattering with spherical proportional counters

Dark matter (DM) detectors employing a spherical proportional counter (SPC) have demonstrated a single-electron detection threshold and are projected to have small background rates. We explore the sensitivity to DM-electron scattering with SPC detectors in the context of darksphere, a proposal for a 300 cm diameter fully electroformed SPC. SPCs can run with different gases, so we investigate the sensitivity for five targets: helium, neon, xenon, methane, and isobutane. We use tools from quantum chemistry to model the atomic and molecular systems and calculate the expected DM induced event rates. We find that darksphere has the potential to improve current exclusion limits on DM masses above 4 MeV by up to 5 orders of magnitude. Neon is the best all-round gas target and provides good sensitivity to scenarios with both light and heavy mediators. Gas mixtures, where methane or isobutane is added to a noble gas, can extend the sensitivity at lower masses. Our study highlights the currently untapped potential of SPCs to search for DM-electron scattering in the MeV-to-GeV DM mass range.

Blazar Constraints on Neutrino-Dark Matter Scattering.

Neutrino emission in coincidence with gamma rays has been observed from the blazar TXS 0506+056 by the IceCube telescope. Neutrinos from the blazar had to pass through a dense spike of dark matter (DM) surrounding the central black hole. The observation of such a neutrino implies new upper bounds on the neutrino-DM scattering cross section as a function of DM mass. The constraint is stronger than existing ones for a range of DM masses, if the cross section rises linearly with energy. For constant cross sections, competitive bounds are also possible, depending on details of the DM spike.

Astrophysical observations of a dark matter-Baryon fifth force

We consider the effects of an attractive, long-range Yukawa interaction between baryons and dark matter (DM), focusing in particular on temperature and pulsar timing observations of neutron stars (NSs). We show that such a fifth force, with strength modestly stronger than gravity at ranges greater than tens of kilometers (corresponding to mediator masses less than 10-11eV), can dramatically enhance dark matter kinetic heating, capture, and pulsar timing Doppler shifts relative to gravity plus short range interactions alone. Using the coldest observed NS and pulsar timing array (PTA) data, we derive limits on fifth force strength over a DM mass range spanning light dark matter up to order solar mass composite DM objects. We also consider an indirect limit by combining bullet cluster limits on the DM self-interaction with weak equivalence principle test limits on baryonic self-interactions. We find the combined indirect limits are moderately stronger than kinetic heating and PTA limits, except when considering a DM subcomponent.

Bounds on boosted dark matter from direct detection: The role of energy-dependent cross sections

The recoil threshold of Direct Detection experiments limits the mass range of Dark Matter (DM) particles that can be detected, with most DD experiments being blind to sub-MeV DM particles. However, these light DM particles can be boosted to very high energies via collisions with energetic Cosmic Ray electrons. This allows Dark Matter particles to induce detectable recoil in the target of Direct Detection experiments. We derive constraints on scattering cross section of DM and electron, using XENONnT and Super-Kamiokande data. Vector and scalar mediators are considered, in the heavy and light regimes. We discuss the importance of including energy dependent cross sections (due to specific Lorentz structure of the vertex) in our analysis, and show that the bounds can be significantly different than the results obtained assuming constant energy-independent cross-section, often assumed in the literature for simplicity. Our bounds are also compared with other astrophysical and cosmological constraints.