XENON1T Anomaly and its Implication for Decaying Warm Dark Matter

TL;DR

This paper links the XENON1T electronic recoil excess to a decaying warm dark matter model where dark photons produced by WDM decay explain the anomaly, potentially contributing significantly to current dark matter.

Contribution

It proposes a novel decaying warm dark matter model that accounts for the XENON1T anomaly and addresses small scale structure issues and the H0 tension.

Findings

Dark photon from WDM decay can explain the XENON1T excess.

Dark photon may be the main or a sub-component of dark matter.

Model addresses small scale problems and H0 tension.

Abstract

An excess in the electronic recoil data was observed in the XENON1T detector. One of plausible explanations for the excess is absorption of a vector bosonic particle with the mass of $2-3\,{\rm keV}$. For this, the kinetic mixing $\kappa\!\sim\!10^{-15}$ of the dark photon with the photon is required if the dark photon explains the current DM abundance. We recently proposed a model where the main component DM today is a decaying warm dark matter (WDM) with the life time comparable to the age of the current universe. The WDM decays to a massless fermion and a massive dark photon. This model was originally designed for addressing both the small scale problems which $\Lambda$CDM suffers from and the $H_{0}$ tension. In this letter, we show that the massive dark photon produced by the WDM decay can be identified with the vector boson inducing the anomalous excess in the XENON1T experiment. Depending on a lifetime of the parent decaying WDM, the dark photon could be either the main component or the sub-component of DM population today.