Can Nonstandard Neutrino Interactions explain the XENON1T spectral excess?

TL;DR

This paper investigates whether nonstandard neutrino interactions, including magnetic moments, charge radius, millicharge, and light mediators, can explain the XENON1T electron recoil excess within experimental limits.

Contribution

It provides a comprehensive spectral fit analysis showing that certain neutrino properties and light mediators can account for the excess, offering new constraints on these parameters.

Findings

Neutrino magnetic moment around 2-4×10^{-11} μ_B can explain the excess.

Light mediators with 10-100 keV masses fit the spectral data.

Constraints on neutrino millicharge, magnetic moment, and mediator couplings are derived.

Abstract

We perform a constrained spectral fit analysis of the excess observed in the electron recoil energy spectrum by XENON1T with neutrino magnetic moment, charge radius, neutrino millicharge and new light vector and scalar mediators. Within the limits allowed by other laboratory experiments we find that the excess can be explained in the range$\ (2-4)\times 10^{-11}\mu _{B} $ for the magnetic moment,$\ (2-6)\times 10^{-31}$cm$^{2}$ for the charge radius, $\ (1.7-2.3)\times 10^{-12}e$ for the millicharge and $(10-100)\ $keV masses of light mediators with couplings of $ 3.5\times 10^{-7}$ for vector/axial-vector, $1\times 10^{-6}$ and $4\times 10^{-6}$ for scalar and pseudo-scalar mediators respectively. Among all neutrino millicharge, magnetic moment and vector mediators fit better to the observed spectrum. We also derive constraints on all new physics parameters considered here.