Light vector mediators facing XENON1T data

D Aristizabal Sierra,V De Romeri,L.J Flores,D.K Papoulias

doi:10.1016/j.physletb.2020.135681

Abstract

Recently the XENON1T collaboration has released new results on searches for new physics in low-energy electronic recoils. The data shows an excess over background in the low-energy tail, particularly pronounced at about 2−3keV. With an exposure of 0.65 tonne-year, large detection efficiency and energy resolution, the detector is sensitive as well to solar neutrino backgrounds, with the most prominent contribution given by pp neutrinos. We investigate whether such signal can be explained in terms of new neutrino interactions with leptons mediated by a light vector particle. We find that the excess is consistent with this interpretation for vector masses below ≲0.1MeV. The region of parameter space probed by the XENON1T data is competitive with constraints from laboratory experiments, in particular GEMMA, Borexino and TEXONO. However we point out a severe tension with astrophysical bounds and cosmological observations.

Highlights

Dark matter (DM) direct detection experiments have entered the era of ton-size active volumes, and will keep going in that direction in their search for DM signals [1,2,3,4,5]
Conventional searches using nuclear recoil energy measurements allow searches of DM in the GeV-TeV range, while electron recoil measurements provide a tool for sub-GeV DM and other well-motivated degrees of freedom such as axion-like particles (ALPs) and/or dark photons [6,7]
Light vector mediators generate spectral features, modifying the recoil energy dependence of the differential cross section, which increases at low Er for sufficiently small vector boson masses

Summary

Introduction

Dark matter (DM) direct detection experiments have entered the era of ton-size active volumes, and will keep going in that direction in their search for DM signals [1,2,3,4,5]. The collaboration has reported an excess below 7 keV with a prominent feature towards 2 − 3 keV Using this data, three new physics scenarios were explored as possible explanations to the signal: the solar axion model, neutrino magnetic moment and bosonic dark matter. The background hypothesis cannot be discarded, one can as well entertain the possibility that the excess is driven by new physics Seemingly, this has been the approach the collaboration has adopted. The new degrees of freedom could e.g. involve DM or particles from a dark sector [18,19,20,21,22] Another possibility, which goes along the lines of the neutrino magnetic moment, is an interaction that locally enhances the elastic scattering neutrino-electron cross section [23].

Light vector mediator scenarios and solar neutrino background

Findings

Conclusions