A bstract Atmospheric collisions can copiously produce dark sector particles in the invisible dark photon model, leading to detectable signals in underground neutrino detectors. We consider the dark photon model with the mass mixing mechanism and use the Super-K detector to detect the electron recoil events caused by the atmospherically produced dark sector particles within the model. We find that the combined data from four Super-K runs yield new leading constraints for the invisible dark photon in the mass range of ~ (0.69 0.87) GeV, surpassing various previous constraints, including those from BaBar and NA64.

Taming the dark photon production via a non-minimal coupling to gravity

In this study, we propose an investigation into dark photon dark matter (DPDM) within the infraredfrequency band, utilizing highly sensitive infrared light detectors commonly integrated into spacetelescopes, such as the James Webb Space Telescope (JWST). The presence of DPDM induces electronoscillations in both the reflectors and the interior of the detectors. Consequently, theseoscillating electrons can emit monochromatic electromagnetic waves with a frequency almostequivalent to the mass of DPDM. By employing the stationary phase approximation, we can demonstratethat when the size of the reflector significantly exceeds the wavelength of the electromagneticwave, the contribution to the electromagnetic wave field at a given position primarily stems fromthe surface unit perpendicular to the relative position vector. This simplification results in thereduction of electromagnetic wave calculations to ray optics. Through a careful analysis of photongeneration induced by DPDM on the various optical elements of JWST, we find that the contribution ofthese photons to the detected signal is negligible. Nevertheless, we propose a modifiedconfiguration of the JWST mirrors that would enable the DPDM-induced photons to be focused onto thedetector. This approach can be applied to future space telescopes during their ground-testingphases. Using the JWST parameters as a representative example, the achievable upper limits on theDPDM-photon mixing constant are ϵ ∼ 10-12–10-14 in the frequency range10–500 THz at the 95% confidence level. This reveals the strong potential of future spacetelescopes for DPDM detection during ground testing, with sensitivities exceeding current limits by1 to 2 orders of magnitude compared with the XENON1T result and the solar cooling bound.

Gravitational lensing, shadow images and accretion dynamics of dark photon corrected black holes

A bstract We extend the Standard Model (SM) by introducing a U(1) ′ gauge boson and a real pseudo-scalar field, both odd under a ℤ 2 symmetry. The resulting low-energy spectrum consists of a stable vector as the dark matter candidate, and a pseudo-scalar mediator, which interacts with the SM via a Higgs portal coupling and a dimension-five portal connecting it to both the dark and visible photons. We explore the freeze-in of both particles at low reheating temperature, finding a rich yield evolution dynamics in the early Universe. This setup brings a consistent dark matter scenario in which the dark photon relic abundance is generated through freeze-in at low reheating temperatures. In addition to its cosmological viability, the model can be tested at the LHC: Higgs bosons can decay into dark photons and displaced visible photons via the long-lived mediator. These signatures allow us to constrain the Higgs portal coupling using recent searches for non-pointing photons and limits on invisible or undetected Higgs decays. We derive meaningful constraints on the dark matter parameter space, in particular excluding a thermalized mediator in the region compatible with the observed relic abundance.

We report dark photon results from HAYSTAC phase II using data from previously reported axion searches. Additionally, we present an analysis of an unpublished dataset covering a region between 19.46 – 19.52 μeV . This region overlaps with a recently reported dark photon signal at 19.5 μeV with a kinetic coupling strength of | χ rand | ≃ 6.5 × 10 − 15 resulting from a reanalysis of previously published data from the TASEH collaboration. Given HAYSTAC’s sensitivity, if such a signal were present, it would have appeared as a large 17.1 σ excess above the noise. However, no such signal was observed. We thus exclude couplings | χ rand | ≥ 4.90 × 10 − 15 at the 90% confidence level over the newly reported region. In addition, using our previously reported axion data, we exclude couplings | χ rand | ≥ 2.90 × 10 − 15 between 16.96 – 19.46 μeV at the 90% confidence level.

We investigate the sensitivity of proposed circular electron positron collider (CEPC) and future circular collider in its electron–positron mode (FCC-ee) with a center-of-mass energy of 240 GeV to long-lived dark photons heavier than 2 GeV that are pair produced via the prompt decays of a light scalar mixed with the Standard-Model Higgs boson. We compute the production and decay rates of both the light scalar and the dark photon, and develop two search strategies targeting displaced vertices within the inner tracker of the main detectors. Using Monte Carlo simulations, we evaluate the signal acceptance and projected sensitivity for each strategy. Our results show that, for the scalar-Higgs mixing angle set at 10 − 2 just below the current upper limit, the proposed searches at CEPC and FCC-ee can probe a dark-photon kinetic-mixing parameter several orders of magnitude below existing bounds, for dark photons lighter than half the dark-scalar mass.

We report a laboratory search for ultralight dark photon dark matter using a , array of commercial scalar optically pumped magnetometers. In the low-frequency regime where the Earth–ionosphere system acts as an electromagnetic transducer, the expected magnetic signal is a narrow-band triplet of frequencies. This signature consists of a central peak at the dark photon’s Compton frequency, accompanied by two sidebands shifted by Earth’s sidereal rotation frequency. Because scalar magnetometers measure field magnitude, the observable signal is the projection of the oscillating dark photon magnetic field onto the direction of the large, local geomagnetic field. This preserves the crucial triplet signature in the resulting time series data. Analyzing 10.5 h of continuous data, we construct a six-channel complex data vector by evaluating the discrete-time Fourier transform for both sensors directly at the three physical frequencies of the signal triplet. Assuming complex-Gaussian noise, we develop a likelihood framework to set robust, frequency-resolved upper limits on the kinetic-mixing parameter ϵ , which governs the coupling between Standard Model photons and dark photons. Within the mass range 4 × 10 − 15 eV ≲ m A ′ ≲ 3 × 10 − 14 eV , we obtain the most stringent direct laboratory limits to date on the kinetic-mixing parameter, which are complementary to existing astrophysical bounds, including those inferred from observations of the Leo T dwarf galaxy.

A bstract The Light Dark Matter eXperiment (LDMX) is proposed to employ a thin tungsten target and a multi-GeV electron beam to carry out a missing momentum search for the production of dark matter candidate particles. We study the sensitivity for a complementary missing-energy-based search using the LDMX Electromagnetic Calorimeter as an active target with a focus on early running. In this context, we construct an event selection from a limited set of variables that projects sensitivity into previously-unexplored regions of light dark matter phase space — down to an effective dark photon interaction strength y of approximately 2 × 10 − 13 (5 × 10 − 12 ) for a 1 MeV (10 MeV) dark matter candidate mass.

Follow-up search for a tentative dark photon signal near 19.5 eV using the ORGAN-Q infrastructure

A bstract Dark photons with kinetic mixing are compelling mediators for the interactions between dark matter and Standard Model particles. While most experimental searches focus on fully visible or fully invisible decays of dark photons, we explore processes that involve dark Higgs-strahlung, i.e. the emission of a dark Higgs boson connected to the mass generation of the dark photon. If the dark Higgs boson is the lightest dark sector particle, it is expected to be long-lived and decay into Standard Model particles via Higgs mixing. At electron-positron colliders, dark Higgs-strahlung may occur either in isolation (leading to a single displaced vertex and missing energy) or accompanied by a photon from initial-state radiation. Both signatures offer distinctive kinematic features, such as peaks in photon energy or missing invariant mass, which enable efficient background suppression and enhance sensitivity beyond existing searches. Our study suggests that Belle II could significantly improve coverage of dark sector models by targeting this previously unexplored final state and that combining dark Higgs-strahlung events with and without additional photon offers great potential for reconstructing the properties of the dark sector.

The upcoming Deep Synoptic Array 2000 (DSA-2000) will map the radio sky at 0.7–2 GHz (2.9 – 8.3 μeV) with unprecedented sensitivity. This will enable searches for dark matter and other physics beyond the Standard Model, of which we study four cases: axions, dark photons, dark matter subhalos and neutrino masses.We forecast DSA-2000's potential to detect axions through two mechanisms in neutron star magnetospheres: photon conversion of axion dark matter and radio emission from axion clouds, developing the first analytical treatment of the latter.We also forecast DSA-2000's sensitivity to discover kinetically mixed dark photons from black hole superradiance, constrain dark matter substructure and fifth forces through pulsar timing, and improve cosmological neutrino mass inference through fast radio burst dispersion measurements. Our analysis indicates that in its planned five year run the DSA-2000 could reach sensitivity to QCD axion parameters, improve current limits on compact dark matter by an order of magnitude, and enhance cosmological weak lensing neutrino mass constraints by a factor of three.

We present a novel application of a qubit-coupled phonon detector to search for new physics, e.g., ultralight dark matter (DM) and high-frequency gravitational waves. The detector, motivated by recent advances in quantum acoustics, is composed of superconducting transmon qubits coupled to high-overtone bulk acoustic resonators ( h BARs ) and operates in the GHz − 10 GHz frequency range. New physics can excite O ( 10 μ eV ) phonons within the h BAR , which are then converted to qubit excitations via a transducer. We detail the design, operation, backgrounds, and expected sensitivity of a prototype detector, as well as a next-generation detector optimized for new physics signals. We find that a future detector can complement current haloscope experiments in the search for both dark photon DM and high-frequency gravitational waves. Lastly, we comment on such a detector’s ability to operate as a O ( 10 μ eV ) athermal phonon sensor for sub-GeV DM detection.

Abstract Both axion and dark photon dark matter are among the most promising candidates of dark matter. What we know with some confidence is that they exhibit a small velocity distribution δv ≲ v ∼ 10 −3 c . In addition, their mass is small, resulting in a long de Broglie wavelength and a high particle number density. Their phase space distribution contains many uncertainties, so they could give rise to either a coherent or noncoherent wave on the laboratory scale. In this paper, we demonstrated that a resonant cavity can enhance noncoherent axion-to-photon or dark photon-to-photon transitions, and the resulting power is the same as in the coherence case. The classical picture explanation is that a cavity can resonant with multiple different sources simultaneously. This aligns with the quantum perspective, where the cavity boosts dark matter particles transitioning into photons similarly to the Purcell effect. This effect increases the density of states near resonance, regardless of the coherence nature of dark matter. Certainly, the induced microwave signals in a cavity are also non-coherent, and in such case, a single-photon readout may be required.

A bstract Results from the study of the rare decays $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ K + → π + ν ν ¯ , K + → π + μ + μ − and K + → π + γγ at the NA62 experiment at CERN are interpreted in terms of improved limits for $$ \mathcal{B}\left({K}^{+}\to {\pi}^{+}X\right) $$ B K + → π + X and coupling parameters of hidden-sector models, where X is a mediator. World-leading limits are achieved for dark photon, dark scalar and axion-like particle models.

Dark photons, the hypothetical gauge bosons associated with an additional U ( 1 ) ′ symmetry, can couple to standard model particles through a small kinetic mixing parameter ɛ with the ordinary photon. This mechanism provides a portal between the dark sector and visible matter. In this study, we present a procedure to derive theoretical upper bounds on the kinetic mixing parameter ɛ 2 ( M U ) by analyzing dilepton spectra from heavy-ion collisions across a broad energy range, from SIS to LHC energies. Our analysis is based on the microscopic parton-hadron-string dynamics (PHSD) transport approach, which successfully reproduces the measured dilepton spectra in p + p , p + A , and A + A collisions across the same energy range. Besides the dilepton channels resulting from interactions and decays of standard model particles (such as mesons and baryons), the PHSD has been extended to include the decay of hypothetical dark photons into dileptons, U → e + e − . The production of these dark photons occurs via Dalitz decays of π 0 , η , ω , η ′ , and Δ resonances; direct decays of ρ , ω , and ϕ ; the kaon mode K + → π + U ; and thermal q q ¯ annihilation in the quark-gluon plasma. Our results show that high-precision measurements of dilepton spectra in heavy-ion collisions provide a sensitive and competitive probe of dark photons in the MeV to multi-GeV mass range. Furthermore, we quantify the experimental accuracy required to constrain the remaining viable parameter space of kinetic mixing in dark photon scenarios.

We explore the advantages of a polarized electron beam at Belle II, as proposed for “Chiral Belle,” in the search for invisibly decaying (dark) bosons that weakly couple to the Standard Model. By measuring the polarization dependence of the production cross section of dark bosons in association with a photon, the dark boson’s spin and Lorentz structure of its couplings can potentially be determined. We analyze the mono-photon channel e + e − → γ + invisible in detail, focusing on the production of an on-shell spin-1 boson. We explore this in the context of three separate scenarios for a new dark vector: a dark photon, a mass-mixed “dark Z ,” and a vector that couples to right-handed electrons, and we estimate how well the couplings of such bosons to electrons can be constrained in the event of a positive signal.

We study a U ( 1 ) ⊗ U ( 1 ) system coupled to scalar fields. Initially, the model is studied in a novel continuum formulation and study of the appropriate diagonalizations is performed. Three models are examined, in two of which the scalar field couples with both gauge fields while in the third one the scalar field couples only to the dark photon. The model is then treated on a space-time lattice. We determine the phase diagram for various values of the kinetic coupling parameter. Then there follows the determination of masses for the scalar fields and the massive gauge fields, as well as the fine structure constants for the massless gauge fields.

Various theories of dark matter predict distinctive astrophysical signatures in gravitational-wave sources that could be observed by ground- and space-based laser interferometers. Different candidates—including axions, dark photons, macroscopic dark matter, WIMPs and dark-matter spikes—may appear in interferometer data via their coupling to gravity or the Standard Model, altering the measured gravitational-wave strain in distinct ways. Despite their differences, these candidates share two key features: (1) they can be probed through their effects on gravitational waves from inspiraling compact objects, isolated black holes and neutron stars, or via direct interactions with detectors and (2) their signatures likely persist far longer than the seconds-long mergers detected today, necessitating new data analysis methods beyond matched filtering. This review outlines these dark matter candidates, their observational signatures and approaches for their detection.

Superradiance, geodesics and shadows of black holes in dark photon with higher-order correction