Can Nonstandard Neutrino Interactions explain the XENON1T spectral excess?

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.

Comments: Version3. Published version. 8 pages, 5 figures, 2 tables and more references added. Typos fixed and analysis and discussion of millicharged neutrinos extended