Dark Matter Candidate Research Articles

Observational prospects of self-interacting scalar superradiance with next-generation gravitational-wave detectors

Abstract Current- and next-generation gravitational-wave observatories may reveal new, ultralight bosons. Through the superradiance process, these theoretical particle candidates can form clouds around astrophysical black holes and result in detectable gravitational-wave radiation. In the absence of detections, constraints—contingent on astrophysical assumptions—have been derived using LIGO-Virgo-KAGRA data on boson masses. However, the searches for ultralight scalars to date have not adequately considered self-interactions between particles. Self-interactions that significantly alter superradiance dynamics are generically present for many scalar models, including axion-like dark matter candidates and string axions. We implement the most complete treatment of particle self-interactions available to determine the gravitational-wave signatures expected from superradiant scalar clouds and revisit the constraints obtained in a past gravitational-wave search targeting the black hole in Cygnus X-1. We also project the reach of next-generation gravitational-wave observatories to scalar particle parameter space in the mass-coupling plane. We find that while proposed observatories have insufficient reach to self-interactions that can halt black hole spin down, next-generation observatories are essential for expanding the search beyond gravitational parameter space and can reach a mass and interaction scale of ∽ 10-13–10-12 eV/c2 and ≥ 1017 GeV, respectively.

Sensitivity of two-mode SRF cavity to generic electromagnetism of sub-μeV dark matter

Abstract The low-mass dark matter (DM) such as axion or wavelike scalar plays as a plausible DM candidate. Recently, the possible non-standard couplings of low-mass DM draw much attention. In this work we investigate the detection of electromagnetic couplings in a few benchmark models of low-mass DM. For illustration, we consider the generic axion electrodynamics including CP violating coupling as well as the newly proposed axion electromagnetodynamics.
The superconducting radio frequency (SRF) cavity with two-mode has more advantages than the traditional cavity approach with static background field. We utilize the two-mode SRF cavity to probe the generic couplings of low-mass DM with frequency lower than GHz. The choices of the transverse electromagnetic modes are explicitly specified for the detection. We show the sensitivity of the SRF cavity to the axion couplings in the above frameworks.

Warm Surprises from Cold Duets: N-Body Simulations with Two-Component Dark Matter

Abstract We explore extensive N-body simulations with two-component cold dark matter candidates. We delve into the temperature evolution, power spectrum, density perturbation, and maximum circular velocity functions. We find that the substantial mass difference between the two candidates and the annihilation of the heavier components to the lighter ones effectively endow the latter with warm dark matter-like behavior, taking advantage of all distinct features that warm dark matter candidates offer, without observational bounds on the warm dark matter mass. Moreover, we demonstrate that the two-component dark matter model aligns well with observational data, providing valuable insights into where and how to search for the elusive dark matter candidates in terrestrial experiments.

Dark sector tunneling field potentials for a dark big bang

All of the significant evidence for dark matter observed thus far has been through its gravitational interactions. After 40 years of direct detection experiments, the parameter space for weakly interacting massive particles (WIMPs) as dark matter candidates is rapidly approaching the neutrino floor. Moreover, there have been no signs of WIMPs in any particle production experiments so far. In this light, we consider a dark sector that is strongly decoupled from the visible sector, interacting exclusively through gravity. In this model, proposed by Freese and Winkler [Dark matter and gravitational waves from a dark big bang, ], dark matter can be produced through a first-order phase transition in the dark sector dubbed “the dark big bang.” We fully determine the allowed region of parameter space for the tunneling potential that leads to the realization of a dark big bang and is consistent with all experimental bounds available. Published by the American Physical Society 2024

Probing stochastic ultralight dark matter with space-based gravitational-wave interferometers

Ultralight particles are theoretically well-motivated dark matter candidates. In the vicinity of the Solar System, these ultralight particles can be described as a superposition of plane waves, resulting in a stochastic field with sizable amplitude fluctuations on scales determined by the velocity dispersion of dark matter. In this work, we systematically investigate the sensitivity of space-based gravitational-wave interferometers to the stochastic ultralight dark matter field within the frequentist framework. We derive the projected sensitivity of a single detector using the time-delay interferometry. Our results show that space-based gravitational-wave interferometers have the potential to probe unconstrained regions in parameter space and improve the current limit on coupling strengths. Furthermore, we explore the sensitivity of a detector network and investigate the optimal configuration for ultralight dark matter detection. We introduce the overlap reduction function for ultralight dark matter, which quantifies the degree of correlation between the signals observed by different detectors. We find that the configuration, where the signals observed by two detectors are uncorrelated, is the optimal choice for ultralight dark matter detection due to a smaller chance of missing signals. This contrasts with the detection of stochastic gravitational-wave background, where the correlated configuration is preferred. Our results may provide useful insights for potential joint observations involving space-based gravitational-wave detectors like LISA and Taiji, as well as other ultralight dark matter detection networks operating in the coherence limit. Published by the American Physical Society 2024

Complex scalar dark matter in a new gauged U(1) symmetry with kinetic and direct mixings

We propose a scalar dark matter model featuring a hidden gauge symmetry, denoted as U(1)X, with two complex scalars, Φ and S. In this framework, Φ spontaneously breaks the U(1)X gauge symmetry while S serves as a viable dark matter candidate. Particularly, the kinetic and direct mixings between the U(1)X and U(1)Y gauge groups provide a portal between dark matter and the Standard Model particles. These mixings offer a plausible explanation for the W boson mass anomaly observed by the Collider Detector at Fermilab Collaboration. We study the comprehensive phenomenological constraints of this model from colliders and dark matter detection experiments, including Z′ searches at the LHC, the 125 GeV Higgs boson measurements, the relic density of dark matter, and the indirect detection of dark matter annihilation. By randomly scanning the parameter space, we find that the regions where mZ′≳4750 GeV and mZ′≲4750 GeV for gx close to 1 remain viable and can be tested by future experiments. Published by the American Physical Society 2024

U(1)-charged Dark Matter in three-Higgs-doublet models

We explore three-Higgs-doublet models that may accommodate scalar Dark Matter where the stability is based on an unbroken U(1)-based symmetry, rather than the familiar ℤ2 symmetry. Our aim is to classify all possible ways of embedding a U(1) symmetry in a three-Higgs-doublet model. The different possibilities are presented and compared. All these models contain mass-degenerate pairs of Dark Matter candidates due to a U(1) symmetry unbroken (conserved) by the vacuum. Most of these models preserve CP. In the CP-conserving case the pairs can be seen as one being even and the other being odd under CP or as having opposite charges under U(1). Not all symmetries presented here were identified before in the literature, which points to the fact that there are still many open questions in three-Higgs-doublet models. We also perform a numerical exploration of the U(1) × U(1)-symmetric 3HDM, this is the most general phase-invariant (real) three-Higgs-doublet model. The model contains a multi-component Dark Matter sector, with two independent mass scales. After imposing relevant experimental constraints we find that there are possible solutions throughout a broad Dark Matter mass range, 45–2000 GeV, the latter being a scan cutoff.

Majoron-driven leptogenesis in gauged U(1)Lμ−Lτ model

We propose a novel leptogenesis scenario in the gauged U(1)Lμ−Lτ model. Achieving successful leptogenesis in the U(1)Lμ−Lτ symmetric phase is challenging due to the absence of a CP phase, caused by restriction from the gauge symmetry. To overcome this issue, we introduce an additional global symmetry, U(1)B−L, and a scalar field Φ responsible for breaking this symmetry. Through the kinetic misalignment mechanism, the Majoron field associated with U(1)B−L symmetry breaking has a kinetic motion in the early Universe. Subsequently, time-dependent Majoron field background induces the background CP phase dynamically, leading to successful leptogenesis in the U(1)Lμ−Lτ symmetric phase. Furthermore, Majoron itself serves as a dark matter candidate in this scenario. As one of the phenomenological applications, we consider the model that can also explain the muon g−2 anomaly. Published by the American Physical Society 2024

Dark matter as the trigger of flavor changing neutral current decays of the top quark

We suggest a simplified model that simultaneously addresses the dark matter problem and gives rise to top-quark flavor changing neutral current (FCNC) interactions at the one-loop order. The model consists of two extra SU(2)L gauge singlets: a colored mediator of spin zero (S) and a right-handed fermion (χ); both are odd under an Z2 symmetry. The right-handed fermion plays the role of the dark matter candidate. In this model, the presence of the two dark sector particles generates one-loop induced FCNC decays of the top quark into light quarks and bosons such as the gluon, the photon, the Z boson, or the Higgs boson. As a case study, we analyze the top-quark FCNC decays into light quarks (u or c) and Z or Higgs bosons. We then study the reliable solutions to the dark matter problem by estimating the regions in the parameter space that are consistent with the measurement of the dark matter relic density. We also revisit the bounds from the searches of dark matter in events with at least one high-pT jet and large missing transverse energy at the Large Hadron Collider (LHC). We then define four benchmark points that are consistent with the existing constraints from collider experiments and cosmology. We finally estimate, for these benchmark scenarios, the rates of a broad range of channels that can be used to probe the connection between the top FCNC transitions and dark matter, both at the HL-LHC and at a future 100 TeV collider. Published by the American Physical Society 2024

Freezing-in cannibal dark sectors

Self-Interacting Dark Matter models can successfully explain dark matter (DM) production through interactions confined within the dark sector. However, they often lack measurable experimental signals due to their secluded nature. Including a feeble interaction with the visible sector through a Higgs portal leads not only to potential detection avenues and richer thermal production dynamics, but also to a possible explanation of the initial dark sector population through the freeze-in mechanism. In this work we study, by solving the full system of coupled Boltzmann equations for the number densities and temperatures of all the involved states, three scenarios of this type where the DM is: a real scalar with broken ℤ2, a complex scalar with unbroken ℤ3, and a ℤ3 scalar with an additional scalar mediator. All of these models have viable dark matter candidates in a cannibal phase while having different detection profiles. We show that cosmological bounds can be either exacerbated or evaded by changing the dark sector interactions, leading to potential signatures in long-lived particle and indirect detection experiments.

Stealth dark matter spectrum using Laplacian Heaviside smearing and irreducible representations

We present nonperturbative lattice calculations in the quenched approximation of the low-lying meson and baryon spectrum of the SU(4) gauge theory with fundamental fermion constituents. This theory is one instance of stealth dark matter, a class of strongly coupled theories, where the lowest mass stable baryon is the dark matter candidate. This work constitutes the first milestone in the program to study stealth dark matter self-interactions. Here, we focus on reducing excited state contamination in the single-baryon channel by applying the Laplacian Heaviside method, as well as projecting our baryon operators onto the irreducible representations of the octahedral group. We compare our resulting spectrum to previous work involving Gaussian smeared nonprojected operators and find good agreement with reduced statistical uncertainties. We also present the spectrum of the low-lying odd-parity baryons for the first time. Published by the American Physical Society 2024

New Constraints on Axion-Mediated Spin Interactions Using Magnetic Amplification.

Axions are highly motivated hypothetical particles beyond the standard model that can be dark matter candidates and address the strong CP problem. Here we search for axion-mediated interactions generated between two separated ^{129}Xe gas ensembles, monitoring and polarizing the ^{129}Xe nuclear spins through spin-exchange interactions with Rb vapor. Our method exploits the magnetic amplification through effective fields from Rb-Xe collisions, increasing the sensitivity for axion-mediated interactions by up to 145-fold relative to conventional methods. Moreover, we employ template filtering to extract exotic interactions with a maximum signal-to-noise ratio. By combining two techniques, axion-mediated interactions are constrained to be less than 10^{-5} of normal magnetic interactions on a length scale of 60mm. We establish new constraints on the neutron-neutron pseudoscalar couplings for a mass range that expands into the well-motivated "axion window" (10 μeV-1 meV), improving previous constraints by up to 50-fold within it and 118-fold outside it. We further discuss promising applications in searches for other axion-nucleon interactions, including axion dark matter and black hole axion bursts with sensitivity well beyond astrophysical limits by several orders of magnitude.

Phenomenology of an extended 1+2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1+2$$\\end{document} Higgs doublet model with S3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S_3$$\\end{document} family symmetry

In order to explain the mass hierarchy and mixing pattern in the leptonic sector, we explore an extension of the Standard Model whose scalar sector includes one active and two inert doublets as well as some scalar singlets. The model includes a S3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S_3$$\\end{document} family symmetry supplemented by extra cyclic symmetries. As a consequence of our construction, a Dark Matter (DM) candidate is predicted and its properties are consistent with the observed cosmic abundances and the constraints imposed by direct and indirect detection experiments. The model allows Charged Lepton Flavor Violation (CLFV) processes like μ→eγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu \\rightarrow e\\gamma $$\\end{document} and μ→3e\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu \\rightarrow 3e$$\\end{document}, but the predicted branching ratios align with experimental limits. Additionally, our analysis elucidates the generation of the active neutrino masses through a one-loop radiative seesaw mechanism matching the observed neutrino oscillation data. The model agrees with experimental data on Higgs Diphoton decay rates and on oblique parameters.

The DAMIC-M Low Background Chamber

The DArk Matter In CCDs at Modane (DAMIC-M) experiment is designed to search for light dark matter (m χ < 10 GeV/c2) at the Laboratoire Souterrain de Modane (LSM) in France. DAMIC-M will use skipper charge-coupled devices (CCDs) as a kg-scale active detector target. Its single-electron resolution will enable eV-scale energy thresholds and thus world-leading sensitivity to a range of hidden sector dark matter candidates. A DAMIC-M prototype, the Low Background Chamber (LBC), has been taking data at LSM since 2022. The LBC provides a low-background environment, which has been used to characterize skipper CCDs, study dark current, and measure radiopurity of materials planned for DAMIC-M. It also allows testing of various subsystems like readout electronics, data acquisition software, and slow control. This paper describes the technical design and performance of the LBC.

Relic abundance of dark matter with [formula omitted](54) flavor symmetry

In this work we discuss the neutrino phenomenology in a Δ(54) discrete flavor symmetry and evaluate the relic abundance of dark matter (DM) and active neutrino-DM mixing angle considering various cosmological constraints. We introduced two Standard Model Higgs particles along with vector-like fermions and a new particle (S) which is a gauge singlet in the Standard Model. This modification leads to a mass matrix that diverges from the tribimaximal neutrino mixing pattern resulting in a non-zero reactor angle (θ13). We also incorporated a Z2⊗Z3⊗Z4 symmetry for the specific interactions in our model. The additional particle S is a sterile neutrino which is considered to be a probable dark matter candidate with mass in keV range.

Neutrinoless double beta decay without vacuum Majorana neutrino mass

We present a proof-of-concept extension to the Standard Model that can generate a non-vanishing neutrinoless double beta decay (0νββ) signal without the existence of Majorana neutrinos or lepton number violation in the zero-density vacuum-ground-state Lagrangian. We propose that the 0νββ can be induced by the capture of an ultralight scalar field, a potential dark matter candidate, that carries two units of lepton number. This makes the observable 0νββ spectrum indistinguishable from the usual 0νββ mechanisms by any practical means. We find that a non-zero 0νββ rate does not require neutrinos to be fundamentally Majorana particles. However, for sizeable decay rates within the range of next-generation experiments, the neutrino will, generally, acquire an (effective) Majorana mass as the scalar field undergoes a transition to the Bose-Einstein condensate phase. We also discuss the distinction between the aforementioned scenario and the case in which the emission of a lepton-number-two scalar leads to 0νββ, exhibiting discernible qualitative features that make it experimentally distinguishable from the conventional scenario.

Limits on scalar dark matter interactions with particles other than the photon via loop corrections to the scalar-photon coupling

There is limited information about the interaction strength of a scalar dark matter candidate with hadrons and leptons for a scalar particle mass exceeding 10−3 eV while its interaction with photon is well studied. The scalar-photon coupling constant receives quantum corrections from one-loop Feynman diagrams which involve the scalar-lepton, scalar-quark, and scalar-W-boson vertices. We calculate these one-loop quantum corrections and find new limits on the scalar particle interactions with electron, muon, tau, quarks, nucleons, gluons, Higgs, and W-bosons by repurposing the results of experiments measuring the scalar-photon interaction. Limits on interactions of heavy leptons and quarks have been obtained for the first time, and limits on other interactions in certain mass intervals are 2 to 15 orders of magnitude stronger than those presented in previous publications and exclude the resolution of the muon g−2 anomaly with scalar particle. Published by the American Physical Society 2024

Improved limits on n→n′ transformation from the Spallation Neutron Source

Conversions between neutrons n and dark matter candidate sterile neutrons n′ have been proposed as a mechanism for baryon number B violation. In the case that there is a small mass difference Δm between the n and the n′ states, oscillations can be induced by compensating for Δm with a magnetic field. A search for such neutron oscillations was performed at the Spallation Neutron Source by looking for anomalous neutron transmission through a strongly absorbing cadmium wafer inside of a 6.6 T magnet. The approach described here saw no regenerated neutrons above background, which provides an improved limit for neutron–sterile neutron transformations for a range of Δm between 0.1 and 1000 neV. Published by the American Physical Society 2024

Lepton-flavor-violating ALP signals with TeV-scale muon beams

We explore the feasibility of using TeV-energy muons to probe lepton-flavor-violating (LFV) processes mediated by an axionlike particle (ALP) a with mass O(10 GeV). We focus on μτ LFV interactions and assume that the ALP is coupled to a dark state χ, which can be either less or more massive than a. Such a setup is demonstrated to be consistent with χ being a candidate for dark matter, in the experimentally relevant regime of parameters. We consider the currently operating NA64-μ experiment and proposed FASERν2 detector as both the target and the detector for the process μA→τAa, where A is the target nucleus. We also show that a possible future active muon fixed-target experiment operating at a 3 TeV muon collider or in its preparatory phase can provide an impressive reach for the LFV process considered, with future FASERν2 data providing a pilot study towards that goal. The implications of the muon anomalous magnetic moment (g−2)μ measurements for the underlying model, in case of a positive signal, are also examined, and a sample UV completion is outlined. Published by the American Physical Society 2024

Rare B and K decays in a scotogenic model

A scotogenic model can radiatively generate the observed neutrino mass, provide a dark matter candidate, and lead to rare lepton flavor-violating processes. We aim to extend the model to establish a potential connection to the quark flavor-related processes within the framework of scotogenesis, enhancing the unexpectedly large branching ratio (BR) of B+→K+νν¯ observed by the Belle II Collaboration. Meanwhile, the model can address tensions between some experimental measurements and standard model (SM) predictions in flavor physics, such as the muon g−2 excess and the higher BR of Bs→μ−μ+. In the model, we introduce the following dark particles: a neutral singlet Dirac-type lepton (N); two inert Higgs doublets (η1,2), with one carrying a lepton number; a charged singlet dark scalar (χ+); and a singlet vectorlike up-type dark quark (T). The first two entities are responsible for the radiative neutrino mass, and χ+ couples to right-handed quarks and leptons and can resolve the tensions existing in muon g−2 and Bs→μ−μ+. Furthermore, the BR of B+→K+νν¯ can be enhanced up to a factor of 2 compared to the SM prediction through the mediations of the dark T and the charged scalars. In addition, we also study the impacts on the K→πνν¯ decays. Published by the American Physical Society 2024