Hidden photon dark matter in the light of XENON1T and stellar cooling

Abstract

The low-energy electronic recoil spectrum in XENON1T provides an intriguing hint for potential new physics. At the same time, observations of horizontal branch stars favor the existence of a small amount of extra cooling compared to the one expected from the Standard Model particle content. In this note, we argue that a hidden photon with a mass of ∼ 2.5 keV and a kinetic mixing of ∼ 10−15 allows for a good fit to both of these excesses. In this scenario, the signal detected in XENON1T is due to the absorption of hidden photon dark matter particles, whereas the anomalous cooling of horizontal branch stars arises from resonant production of hidden photons in the stellar interior.

Exothermic dark matter for XENON1T excess

“…As we will discuss in the next section, some microscopic models with vector-like leptons can induce a suppressed axial vector coupling to the electron. Moreover, there is another loop process for the three-photon decay channel, χ 1 → χ 2 +3γ, but the corresponding decay rate is highly suppressed by Γ ∝ (∆m) 13 /(m 4 Z m 8 e ) [5], thus being consistent with X-ray bounds [37].…”

“…Quite recently, a tantalizing hint has been announced for the potential dark matter signals from the electron recoil events in the recoil energy, E R = 1 − 10 keV, from XENON1T experiment [1]. The origin of the Xenon excess has attracted interest from several groups [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. A simple explanation with the solar axion or the neutrino magnetic dipole moment has been put forward from the XENON1T collaboration, but both cases are inconsistent with the star cooling constraints, because the electron coupling to the axion or the neutrino magnetic dipole moment required for the Xenon excess exceeds them by the order of magnitude [1].…”

Axion-like particles and dark photons - hints from XENON1T and stellar cooling

“…Axion-like particles and dark photons -hints from XENON1T and stellar cooling Figure 1 shows the best-fit interpretation of the XENON1T excess in terms of dark photon absorption. The position and height of the peak are set by the dark photon mass and the kinetic mixing parameter, respectively, which are found to be m X = 2.8 keV and = 8.6 × 10 −16 at the best-fit point [6]. The width of the peak is determined by the detector resolution.…”

“…A particularly appealing explanation is that the XENON1T excess is caused by the absorption of keV-scale bosonic dark matter particles, such as axion-like particles (ALPs) [5] or hidden photons [6], which would convert their entire rest mass into electronic recoil energy. Although such particles would be too light and too weakly coupled to be produced thermally in the early universe, they can be produced through a number of well-known non-thermal processes, such as the misalignment mechanism.…”

Shedding new light on sterile neutrinos from XENON1T experiment

“…In order to avoid large corrections to neutrino masses induced by large neutrino magnetic moments, some new symmetries can be introduced [21,26]. Moreover, there are many theoretical attempts to interpret the XENON1T signal assuming new physics beyond the SM such as, boosted dark matter [27][28][29][30][31][32], dark radiation [33,34], anomalous magnetic moment of muon [23,35], inelastic DM-electron scattering [36][37][38][39][40][41], axion-like DM [10,42]. Besides, there are some proposals using a gauged U (1) X extention of the SM, where a gauge boson Z contributes to dark matter (DM) [43][44][45][46][47][48][49][50][51].…”