Dark Photon Research Articles

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.

Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at sqrt{s} = 13 TeV with the ATLAS detector

A search for light long-lived neutral particles with masses in the O(MeV–GeV) range is presented. The analysis targets the production of long-lived dark photons in the decay of a Higgs boson produced via gluon–gluon fusion or in association with a W boson. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are selected in 139 fb−1 of sqrt{s} = 13 TeV pp collision data collected by the ATLAS detector at the LHC. Background estimates for contributions from Standard Model processes and instrumental effects are extracted from data. The observed event yields are consistent with the expected background. Exclusion limits are reported on the production cross-section times branching fraction as a function of the mean proper decay length cτ of the dark photon, or as a function of the dark-photon mass and kinetic mixing parameter that quantifies the coupling between the Standard Model and potential hidden (dark) sectors. A Higgs boson branching fraction above 1% is excluded at 95% CL for a Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 10 mm and 250 mm and dark photons with masses between 0.4 GeV and 2 GeV.

Rare leptonic processes induced by massless dark photon

We introduce a dark photon considering a U(1) gauge extension of the standard model in particle physics. Provided that the extra U(1) symmetry is unbroken, the dark photon is massless and has no coupling to the standard electromagnetic current. Higher-dimensional operators describe interactions of the massless dark photon with particles in the standard model. We investigate the interactions of the massless dark photon with charged leptons via dipole operators, mainly focusing on the lepton family-violating processes. We present an improved constraint in the polarized two-body muon decay and a set of new bounds in tau decays. We also examine possible lepton family-violating signals of the massless dark photon in future lepton colliders.

Search for dark sector by repurposing the UVX Brazilian synchrotron

We propose the first Search for Dark Sector at the Brazilian Synchrotron Light Laboratory, site of Sirius, a fourth-generation storage ring. We show that UVX, Sirius predecessor, can be a promising dark sector detector, SeDS, with unprecedented sensitivity. The search is based on a 1-3 GeV positron beam impinging on a thick target leading the e^+ e^- rightarrow gamma A' reaction, followed by a missing mass spectrum event reconstruction. We show that SeDS has the potential to probe dark photons with masses up to 55 MeV and kinetic coupling down to epsilon ^2 sim 10^{-12}. Therefore, such experiment would constitute the best dark photon probe worldwide in the 10{-}55 MeV mass range, being able to probe an unexplored region of parameter space.

Exploring maverick top partner decays at the LHC

In this work, we have considered an extension of the standard model (SM) with a $SU(2{)}_{L}$ singlet vectorlike quark (VLQ) with electric charge $Q=+2/3$. The model also contains an additional local $U(1{)}_{d}$ symmetry group and the corresponding gauge boson is the dark photon. The VLQ is charged while all the SM particles are neutral under the new $U(1{)}_{d}$ gauge group. Even though in this model the VLQ possesses many properties qualitatively similar to that of the traditional top partner (${T}_{p}$), there are some compelling differences as well. In particular, its branching ratio to the traditional modes (${T}_{p}\ensuremath{\rightarrow}bW,tZ,th$) are suppressed which in turn helps to evade many of the existing bounds, mainly coming from the LHC experiments. In an earlier work, such a VLQ is referred to as ``maverick top partner''. It has been shown that the top partner in this model predominantly decays to a top quark and a dark photon/dark Higgs pair (${T}_{p}\ensuremath{\rightarrow}t{\ensuremath{\gamma}}_{d},t{h}_{d}$) over a large region of the parameter space. The dark photon can be made invisible and consequently, it gives rise to the missing transverse energy (${\overline{)E}}_{T}$) signature at the LHC detector. We have mainly focused on the LHC signatures and future prospects of such top partners. In particular, we have studied the $t\overline{t}+{\overline{)E}}_{T}$ and $t+{\overline{)E}}_{T}$ signatures in the context of the LHC via pair and single productions of the top partner, respectively at 13 and 14 TeV LHC center of mass energies assuming that the dark photon either decays into an invisible mode or it is invisible at the length scale of the detector. We have shown that one can exclude $\mathrm{sin}{\ensuremath{\theta}}_{L}\ensuremath{\sim}0.025$ (0.05) for ${m}_{{T}_{p}}\ensuremath{\le}2.0\text{ }(2.6)\text{ }\text{ }\mathrm{TeV}$ at $\sqrt{s}=14\text{ }\text{ }\mathrm{TeV}$ with an integrated luminosity of $3\text{ }\text{ }{\mathrm{ab}}^{\ensuremath{-}1}$ using the single top partner production channel.

Resonant production of dark photons from axions without a large coupling

Resonant production of dark photons from axions without a large coupling

Wideband Direct Detection Constraints on Hidden Photon Dark Matter with the QUALIPHIDE Experiment.

We report direction detection constraints on the presence of hidden photon dark matter with masses between 20-30 μeV c^{-2}, using a cryogenic emitter-receiver-amplifier spectroscopy setup designed as the first iteration of QUALIPHIDE (quantum limited photons in the dark experiment). A metallic dish sources conversion photons, from hidden photon kinetic mixing, onto a horn antenna which is coupled to a C band kinetic inductance traveling wave parametric amplifier, providing for near quantum-limited noise performance. We demonstrate a first probing of the kinetic mixing parameter χ to the 10^{-12} level for the majority of hidden photon masses in this region. These results not only represent stringent constraints on new dark matter parameter space, but are also the first demonstrated use of wideband quantum-limited amplification for astroparticle applications.

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

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

Limits on Dark Photons, Scalars, and Axion‐Electromagnetodynamics with the ORGAN Experiment

AbstractAxions are a well‐motivated dark matter candidate, with a host of experiments around the world searching for direct evidence of their existence. The ORGAN Experiment is a type of axion detector known as an axion haloscope, which takes the form of a cryogenic resonant cavity embedded in a strong magnetic field. ORGAN recently completed Phase 1a, a scan for axions ≈65 µeV, and placed the most stringent limits to date on the dark matter axion–photon coupling in this region, . It has been shown that axion haloscopes such as ORGAN are automatically sensitive to other kinds of dark matter candidates, such as dark photons, scalar field/dilaton dark matter, and exotic axion–electromagnetic couplings motivated by quantum electromagnetodynamics. The exclusion limits placed on these various dark matter candidates are computed by ORGAN 1a, and sensitivity for some future ORGAN phases are projected. In particular, the dark photon limits are the most sensitive to date in some regions of the parameter space.

Prospects for the Search for a Leptophilic Scalar and a Dark Photon in Experiments at the Super Charm-Tau Factory

Prospects for the Search for a Leptophilic Scalar and a Dark Photon in Experiments at the Super Charm-Tau Factory

Search for exotic interactions of solar neutrinos in the CDEX-10 experiment

We investigate exotic neutrino interactions using the 205.4−kg·day dataset from the CDEX-10 experiment at the China Jinping Underground Laboratory. New constraints on the mass and couplings of new gauge bosons are presented. Two nonstandard neutrino interactions are considered: a U(1)B–L gauge-boson-induced interaction between an active neutrino and electron/nucleus, and a dark-photon-induced interaction between a sterile neutrino and electron/nucleus via kinetic mixing with a photon. This work probes an unexplored parameter space involving sterile neutrino coupling with a dark photon. New laboratory limits are derived on dark photon masses below 1 eV/c2 at some benchmark values of Δm412 and g′2sin22θ14.Received 21 October 2022Revised 22 November 2022Accepted 17 May 2023DOI:https://doi.org/10.1103/PhysRevD.107.112002Published 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 AreasExtensions of gauge sectorParticle astrophysicsParticle interactionsParticle mixing & oscillationsSolar neutrinosPhysical SystemsHypothetical gauge bosonsNeutrinosSterile neutrinosTechniquesDark matter detectorsNeutrino detectorsSolid-state detectorsParticles & FieldsGravitation, Cosmology & Astrophysics

Search for long-lived particles decaying to a pair of muons in proton-proton collisions at sqrt{s} = 13 TeV

An inclusive search for long-lived exotic particles decaying to a pair of muons is presented. The search uses data collected by the CMS experiment at the CERN LHC in proton-proton collisions at sqrt{s} = 13 TeV in 2016 and 2018 and corresponding to an integrated luminosity of 97.6 fb−1. The experimental signature is a pair of oppositely charged muons originating from a common secondary vertex spatially separated from the pp interaction point by distances ranging from several hundred μm to several meters. The results are interpreted in the frameworks of the hidden Abelian Higgs model, in which the Higgs boson decays to a pair of long-lived dark photons ZD, and of a simplified model, in which long-lived particles are produced in decays of an exotic heavy neutral scalar boson. For the hidden Abelian Higgs model with m(ZD) greater than 20 GeV and less than half the mass of the Higgs boson, they provide the best limits to date on the branching fraction of the Higgs boson to dark photons for cτ(ZD) (varying with m(ZD)) between 0.03 and ≈0.5 mm, and above ≈0.5 m. Our results also yield the best constraints on long-lived particles with masses larger than 10 GeV produced in decays of an exotic scalar boson heavier than the Higgs boson and decaying to a pair of muons.

Thermal production of cold “hot dark matter” around eV

A very simple production mechanism of feebly interacting dark matter (DM) that rarely annihilates is thermal production, which predicts the DM mass around eV. This has been widely known as the hot DM scenario. Despite there are several observational hints from background lights suggesting a DM in this mass range, the hot DM scenario has been considered strongly in tension with the structure formation of our Universe because the free-streaming length of the DM produced from thermal reactions was thought to be too long. In this paper, I show that the previous conclusions are not always true depending on the reaction for bosonic DM because of the Bose-enhanced reaction at very low momentum. By utilizing a simple 1 ↔ 2 decay/inverse decay process to produce DM, I demonstrate that eV range bosonic DM can be thermally produced in a cold manner from a hot plasma through a model-independent analysis applicable to axion, hidden photon, and other bosonic DM candidates. As a result, bosonic DM in the eV mass range may still be unique and theoretically well-motivated. I also discuss some caveats arising from this phenomenon in the freeze-in production of DM, and present a related system that can suppress the hot plasma with thermal reaction.

Toward a UV model of kinetic mixing and portal matter. III. Relating portal matter and right-handed neutrino masses

The kinetic mixing (KM) of a dark photon (DP) with the familiar one of the Standard Model (SM) requires the existence of a new set of fields, called portal matter (PM), which carry both SM and dark sector quantum numbers, some whose masses may lie at the TeV scale. In the vanilla KM model, the dark gauge group is just the simple $G_{Dark}=U(1)_D$ needed to describe the DP while the SM gauge interactions are described by the usual $G_{SM}=SU(3)_c\times SU(2)_L\times U(1)_Y$. However, we need to go beyond this simple model to gain a better understanding of the interplay between $G_{SM}$ and $G_{Dark}$ and, in particular, determine how they both might fit into a more unified construction. Following our previous analyses, this generally requires $G_{Dark}$ to be extended to a non-abelian group, \eg, $SU(2)_I\times U(1)_{Y_I}$, under which both the PM and SM fields may transform non-trivially. In this paper, also inspired by our earlier work on top-down models, we consider extending the SM gauge group to that of the Left-Right Symmetric Model (LRM) and, in doing so, through common vacuum expectation values, link the mass scales associated with the breaking of $G_{Dark}\to U(1)_D$ and the PM fields to that of the RH-neutrino as well as the heavy gauge bosons of the LRM. This leads to an interesting interplay between the now coupled phenomenologies of both visible and dark sectors at least some of which may be probed at, \eg, the LHC and/or at the future FCC-hh.

Millicharged relics reveal massless dark photons

The detection of massless kinetically-mixed dark photons is notoriously difficult, as the effect of this mixing can be removed by a field redefinition in vacuum. In this work, we study the prospect of detecting massless dark photons in the presence of a cosmic relic directly charged under this dark electromagnetism. Such millicharged particles, in the form of dark matter or dark radiation, generate an effective dark photon mass that drives photon-to-dark photon oscillations in the early universe. We also study the prospect for such models to alleviate existing cosmological constraints on massive dark photons, enlarging the motivation for direct tests of this parameter space using precision terrestrial probes.

Direct Detection of Dark Photon Dark Matter Using Radio Telescopes.

Dark photons can be the ultralight dark matter candidate, interacting with Standard Model particles via kinetic mixing. We propose to search for ultralight dark photon dark matter (DPDM) through the local absorption at different radio telescopes. The local DPDM can induce harmonic oscillations of electrons inside the antenna of radio telescopes. It leads to a monochromatic radio signal and can be recorded by telescope receivers. Using the observation data from the FAST telescope, the upper limit on the kinetic mixing can already reach 10^{-12} for DPDM oscillation frequencies at 1-1.5GHz, which is stronger than the cosmic microwave background constraint by about one order of magnitude. Furthermore, large-scale interferometric arrays like LOFAR and SKA1 telescopes can achieve extraordinary sensitivities for direct DPDM search from 10MHz to 10GHz.

Dark photons and displaced vertices at the MUonE experiment

MUonE is a proposed experiment designed to measure the hadronic vacuum polarization contribution to muon $g-2$ through elastic $\mu-e$ scattering. As such it employs an extremely high-resolution tracking apparatus. We point out that this makes MUonE also a very promising experiment to search for displaced vertices from light, weakly-interacting new particles. We demonstrate its potential by showing how it has excellent sensitivity to dark photons in the mass range $10~\mathrm{MeV} \le m_{A'} \le 100~\mathrm{MeV}$ and kinetic mixing parameter $10^{-5} \le \epsilon e \le 10^{-3}$, through the process $\mu^{\pm}\, e^- \to \mu^{\pm}\, e^-\, A'$ followed by $A'\to e^+e^-$.

Detecting Dark Photons with Radio Telescopes

Detecting Dark Photons with Radio Telescopes

Photons from dark photon solitons via parametric resonance

Wave-like dark matter made of spin-1 particles (dark photons) is expected to form ground state clumps called “vector solitons”, which can have different polarizations. In this work, we consider the interaction of dark photons with photons, expressed as dimension-6 operators, and study the electromagnetic radiation that arises from an isolated vector soliton due to parametric resonant amplification of the ambient electromagnetic field. We characterize the directional dependence and polarization of the outgoing radiation, which depends on the operator as well as the polarization state of the underlying vector soliton. We discuss the implications of this radiation for the stability of solitons and as a possible channel for detecting mergers of vector solitons through astrophysical observations.

Dark photon superradiance: Electrodynamics and multimessenger signals

We study the electrodynamics of a kinetically mixed dark photon cloud that forms through superradiance around a spinning black hole, and design strategies to search for the resulting multimessenger signals. A dark photon superradiance cloud sources a rotating dark electromagnetic field which, through kinetic mixing, induces a rotating visible electromagnetic field. Standard model charged particles entering this field initiate a transient phase of particle production that populates a plasma inside the cloud and leads to a system which shares qualitative features with a pulsar magnetosphere. We study the electrodynamics of the dark photon cloud with resistive magnetohydrodynamics methods applicable to highly magnetized plasma, adapting techniques from simulations of pulsar magnetospheres. We identify turbulent magnetic field reconnection as the main source of dissipation and electromagnetic emission, and compute the peak luminosity from clouds around solar-mass black holes to be as large as $10^{43}$ erg/s for open dark photon parameter space. The emission is expected to have a significant X-ray component and is potentially periodic, with period set by the dark photon mass. The luminosity is comparable to the brightest X-ray sources in the Universe, allowing for searches at distances of up to hundreds of Mpc with existing telescopes. We discuss observational strategies, including targeted electromagnetic follow-ups of solar-mass black hole mergers and targeted continuous gravitational wave searches of anomalous pulsars.