Hidden Photon Dark Matter in the Light of XENON1T and Stellar Cooling

TL;DR

This paper proposes that a 2.5 keV hidden photon with tiny kinetic mixing can simultaneously explain the XENON1T electronic recoil excess and the anomalous cooling in horizontal branch stars, suggesting a dark matter candidate.

Contribution

It introduces a specific hidden photon model that accounts for both astrophysical and experimental anomalies with a unified explanation.

Findings

Hidden photon with ~2.5 keV mass fits XENON1T excess

Resonant production explains stellar cooling anomalies

Model consistent with existing astrophysical and experimental constraints

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 $\sim 2.5$ keV and a kinetic mixing of $\sim 10^{-15}$ 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.