Search

Millicharge particles (mCPs) are viable dark matter candidates motivated by many standard model extensions. We show that despite of the tiny coupling with the photon, millicharged dark matters can convert efficiently to photons through annihilation processes in the Earth magnetic field background, which generates a monochromatic quasi static magnetic field signal with angular frequency being twice the millicharged particle mass. By recasting null results from the SuperMAG and the SNIPE Hunt collaborations, we constrain the effective charge of bosonic millicharged dark matter in the mass ranges $10^{-18}-3.5 \times 10^{-17}\,\text{eV}$ and $10^{-15}-10^{-14}\,\text{eV}$. Our bounds surpass current stellar cooling constraints by more than ten orders of magnitude, making this proposal a powerful tool to search for millicharged dark matter., Comment: 7 pages, 2 figures, + Supplemental Materials(5 pages, 2 figures)

We consider Thomson-like processes between dark matter dark photons and free electrons in the Milky Way. The result is a radio signal background that can be detectable with current or future radio telescope arrays. In particular, we computed sensitivity prospects for the Atacama Large Millimeter Array (ALMA) radio telescope and for the future Square Kilometer Array (SKA), concluding that unconstrained parameter space in a wide range of dark photon masses can be probed., Comment: 6 pages, 3 figures

The axion is a hypothetical elementary particle that could solve the long-standing strong CP problem in particle physics and the dark matter mystery in the cosmos. Due to the stimulation of the ambient photons, the axion dark matter decay into photons is significantly enhanced so that its echo signal could be detected by terrestrial telescopes. As a pathfinder, we study the expected sensitivity of searching for the axion dark matter in the mass range between $0.41$ and $1.6\mu\text{eV}$ with the 21 CentiMeter Array (21CMA). We aim to cover the whole 21CMA frequency range in two years by using a 1MW emitter. We find that the resulting sensitivity on the axion-photon coupling could surpass other existing limits by about one order of magnitude., Comment: 7 pages, 6 figures

We consider the effects of a local axion dark matter background on the $g-2$ of the electron. We calculate loop corrections to the photon-electron vertex and determine analytical formulas for the spin and cyclotron frequencies when the electron is in an external magnetic field. By comparing with current measurements of these observables, we are able to place the strongest constraint on the axion-elecron coupling for axion masses below $3\times10^{-18}\text{eV}$., Comment: 6 pages, 2 figures

Earth can act as a transducer to convert ultralight bosonic dark matter (axions and hidden photons) into an oscillating magnetic field with a characteristic pattern across its surface. Here we describe the first results of a dedicated experiment, the Search for Non-Interacting Particles Experimental Hunt (SNIPE Hunt), that aims to detect such dark-matter-induced magnetic-field patterns by performing correlated measurements with a network of magnetometers in relatively quiet magnetic environments (in the wilderness far from human-generated magnetic noise). Our experiment constrains parameter space describing hidden-photon and axion dark matter with Compton frequencies in the 0.5-5.0 Hz range. Limits on the kinetic-mixing parameter for hidden-photon dark matter represent the best experimental bounds to date in this frequency range., Comment: 22 pages, 12 figures. Accepted for publication in PRD. Minor changes in text and updated / improved limits

The axion dark matter echo technique, proposed in Ref. [1], aims to search for axion dark matter by detecting the electromagnetic echo coming from stimulated decay of ambient axion dark matter interacting with a radio-microwave outgoing beam. In this work we consider deviations from the standard halo model (SHM) in the form of fine grained streams that are present in the solar system and use them as a target for the axion echo method, which demonstrates to be very sensitive to particular local axion dark matter phase space distributions. We show that the extremely small dispersion of the streams works in favor of the echo method performance, improving its sensitivity in the axion-photon coupling up to two orders of magnitude, with respect to the isotropic SHM. We also discuss the possibility of targeting high density dark matter hairs formed when fine grained streams focus by the inner Earth's gravitational field., Comment: 9 pages, 4 figures. Any critical feedback the next two weeks is welcomed

The existence of hidden sectors weakly coupled to the visible one has been extensively studied as a way to extend the Standard Model (SM) and to provide a good dark matter candidate. In this work we analyze two models in which gauge and scalar hidden fields interact with the visible sector which, for simplicity we take as an Abelian Higgs model. In one of them, the hidden sector consists of an uncharged scalar. The connection with the visible Abelian Higgs sector is in this case provided by the interaction between the scalars in the two sectors and also by the coupling between the hidden scalar and the visible squared field strength. This model can be seen as an extension of previously studied ones both in high energy and in condensed matter physics and the solutions that we find indicate that it could be relevant in connection to establishing the dark matter relic density. In the second model, both sectors correspond to spontaneously broken gauge theories and hence they feature classical vortex solutions. Introducing three different portals between the two sectors, we analyze the dependence of the model dynamics on the portal parameters and discuss the physical implications in connection with dark matter and gravitational radiation issues., Comment: Matches the final version published in Int.J.Mod.Phys.A 37 (2022)

We demonstrate that ultralight axion dark matter with a coupling to photons induces an oscillating global terrestrial magnetic field signal in the presence of the background geomagnetic field of the Earth. This signal is similar in structure to that of dark-photon dark matter that was recently pointed out and searched for in [arXiv:2106.00022] and [arXiv:2108.08852]. It has a global vectorial pattern fixed by the Earth's geomagnetic field, is temporally coherent on long time scales, and has a frequency set by the axion mass $m_a$. In this work, we both compute the detailed signal pattern, and undertake a search for this signal in magnetometer network data maintained by the SuperMAG Collaboration. Our analysis identifies no strong evidence for an axion dark-matter signal in the axion mass range $2\times10^{-18}\text{eV} \lesssim m_a \lesssim 7\times10^{-17}\text{eV}$. Assuming the axion is all of the dark matter, we place constraints on the axion-photon coupling $g_{a\gamma}$ in the same mass range; at their strongest, for masses $3\times 10^{-17}\text{eV} \lesssim m_a \lesssim 4\times 10^{-17}\text{eV}$, these constraints are comparable to those obtained by the CAST helioscope., Comment: 24 pages, 1 figure. Published version

It was recently shown that a powerful beam of radio/microwave radiation sent out to space can produce detectable back-scattering via the stimulated decay of ambient axion dark matter. This echo is a faint and narrow signal centered at an angular frequency close to half the axion mass. In this article, we provide a detailed analytical and numerical analysis of this signal, considering the effects of the axion velocity distribution as well as the outgoing beam shape. In agreement with the original proposal, we find that the divergence of the outgoing beam does not affect the echo signal, which is only constrained by the axion velocity distribution. Moreover, our findings are relevant for the optimization of the experimental parameters in order to attain maximal signal to noise or minimal energy consumption., Comment: Matches published version

Taking a two interacting scalar toy model with interaction term $g\phi\chi^2$, we study the production of $\chi$ particles coming from the decay of an asymptotic and highly occupied beam of $\phi$ particles. We perform a nonperturbative analysis coming from parametric resonant instabilities and investigate the possibility that massive $\chi$ particles are produced from decays of massless $\phi$ particles from the beam. Although this process is not present in a perturbative analysis, our nonperturbative approach allows it to happen under certain conditions. For a momentum $p$ of the beam particles and a mass $m_\chi$ of the produced ones, we find that the decay is allowed if the energy density of the beam exceeds the instability threshold $p^2 m_\chi^4/(2g^2)$. We also provide an analytical expression for the spontaneous decay rate at the earliest time., Comment: 10 pages, 5 figures

We investigate a scenario where the dark matter of the Universe is made from very light hidden photons transforming under a $Z_{2}$-symmetry. In contrast to the usual situation, kinetic mixing is forbidden by the symmetry and the dark photon interacts with the Standard Model photon only via an axion-like particle acting as a "messenger". Focusing on signatures involving the ordinary photon, our survey of the phenomenology includes limits from cosmological stability, CMB distortions, astrophysical energy loss, light-shining-through-walls experiments, helioscopes and solar X-ray observations., Comment: 45 pages, 8 figures

Axion--photon interactions can lead to an enhancement of the electromagnetic field by parametric resonance in the presence of a cold axion background, for modes with a frequency close to half the axion mass. In this paper, we study the role of the axion momentum dispersion as well as the effects of a background gravitational potential, which can detune the resonance due to gravitational redshift. We show, by analytical as well as numerical calculations, that the resonance leads to an exponential growth of the photon field only if (a) the axion momentum spread is smaller than the inverse resonance length, and (b) the gravitational detuning distance is longer than the resonance length. For realistic parameter values, both effects strongly suppress the resonance and prevent the exponential growth of the photon field. In particular, the redshift due to the gravitational potential of our galaxy prevents the resonance from developing for photons in the observable frequency range, even assuming that all the dark matter consists of a perfectly cold axion condensate. For axion clumps with masses below $\sim 10^{-13}\, M_\odot$, the momentum spread condition is more restrictive, whereas, for more massive clumps, the redshift condition dominates., Comment: 34 pages, 10 figures

Quantum fields with large degeneracy are often approximated as classical fields. Here, we show how quantum and classical evolution of a highly degenerate quantum field with repulsive contact self-interactions differ from each other. Initially, the field is taken to be homogeneous except for a small plane wave perturbations in only one mode. In quantum field theory, modes satisfying both momentum and energy conservation of the quasi-particles, grow exponentially with time. However, in the classical field approximation, the system is stable. We calculate the time scale after which the classical field description becomes invalid., Comment: 15 pages, 4 figures

Electromagnetic radiation with angular frequency equal to half the axion mass stimulates the decay of cold dark matter axions and produces an echo, i.e. faint electromagnetic radiation traveling in the opposite direction. We propose to search for axion dark matter by sending out to space a powerful beam of microwave radiation and listening for its echo. We estimate the sensitivity of this technique in the isothermal and caustic ring models of the Milky Way halo, and find it to be a promising approach to axion, or axion-like, dark matter detection., Comment: 5 pages, 2 figures, includes changes suggested by PRL referees

We study the propagation of photons in a homogeneous axion dark matter background. When the axion decay into two photons is stimulated, the photon field exhibits a parametric instability in a small bandwidth centered on one half of the axion mass. We estimate analytically the enhancement for both coherent and non-coherent axion fields and we find that this effect could be relevant in the context of miniclusters and galactic halos., Comment: 4 pages, 3 figures

Vacuum magnetic birefringence is one of the most interesting non-linear phenomena in quantum electrodynamics because it is a pure photon-photon result of the theory and it directly signalizes the violation of the classical superposition principle of electromagnetic fields in the full quantum theory. We perform analytical and numerical calculations when an electromagnetic wave interacts with an oscillating external magnetic field. We find that in an ideal cavity, when the external field frequency is around the electromagnetic wave frequency, the normal and parallel components of the wave suffer parametric resonance at different rates, producing a vacuum birefringence effect growing in time. We also study the case where there is no cavity and the oscillating magnetic field is spatially localized in a region of length $L$. In both cases we find also a rotation of the elliptical axis.

We study a model where photons interact with hidden photons and millicharged particles through a kinetic mixing term. Particularly, we focus in vacuum birefringence effects and we find a bound for the millicharged parameter assuming that hidden photons are a piece of the local dark matter density, Comment: title changed and a plot added

We study a Light Shinning Through the wall type setup with microwave cavities, where the regeneration cavity has a moving boundary condition oscillating harmonically. We find a parametric resonance that could enhance the probability conversion between Weakly Interacting Slim Particles and photons by several orders of magnitude., Comment: The paper has not been accepted

A variant of quantum electrodynamics coupled to a dark photon through a kinetic mixing is studied. The analogous of the light-light diagram becomes the conversion process $\gamma'\gamma' \to \gamma \gamma$ and an expression for the differential cross section is estimated. For high energies beams, as in LHC, this differential cross section could be measurable and its magnitude would be typically similar to the total cross section of neutrinos, {\it i.e.} $\sim 10^{-50}\,{\text{m}}^2$., Comment: 6pp

We study the local effects of an external time-dependent magnetic field on axion-like particles assuming they are all the dark matter of the universe. We find that under suitable conditions the amplitude of the dark matter field can resonate parametrically. The resonance depends on the velocity of the axion-like particles and scales quadratically with the strength} of the external magnetic field, $\frac{\rho}{\rho_{DM}} \sim {B_0}^3$. By considering typical experimental benchmark values, we find the resonance could amplify around two orders of magnitude the local energy density stored in the dark matter condensate., Comment: This paper has been withdrawn due to errors in the solving of the equations of motion

We point out that a cold dark matter condensate made of gauge bosons from an extra hidden U(1) sector - dubbed hidden- photons - can create a small, oscillating electric density current. Thus, they could also be searched for in the recently proposed LC-circuit setup conceived for axion cold dark matter search by Sikivie, Sullivan and Tanner. We estimate the sensitivity of this setup for hidden-photon cold dark matter and we find it could cover a sizable, so far unexplored parameter space., Comment: 2 columns, 4 pages, 2 figures, v2: some clarifications added, version accepted by EPJC