Low-energy electronic recoil in xenon detectors by solar neutrinos

TL;DR

This paper performs ab initio many-body calculations to accurately determine the low-energy electronic recoil rate caused by solar neutrinos in xenon detectors, revealing a significant suppression compared to previous models and implications for neutrino detection and dark matter searches.

Contribution

It introduces a first-principles calculation of neutrino-induced electronic recoil in xenon, accounting for atomic effects and providing more precise recoil spectra for experimental applications.

Findings

Atomic binding effects suppress neutrino-electron scattering at low energies.

Calculated recoil rate is about 25% lower than previous free-electron models.

Results inform low-energy solar neutrino detection and WIMP background estimation.

Abstract

Low-energy electronic recoil caused by solar neutrinos in multi-ton xenon detectors is an important subject not only because it is a source of the irreducible background for direct searches of weakly-interacting massive particles (WIMPs), but also because it provides a viable way to measure the solar $pp$ and $^{7}\textrm{Be}$ neutrinos at the precision level of current standard solar model predictions. In this work we perform $\textit{ab initio}$ many-body calculations for the structure, photoionization, and neutrino-ionization of xenon. It is found that the atomic binding effect yields a sizable suppression to the neutrino-electron scattering cross section at low recoil energies. Compared with the previous calculation based on the free electron picture, our calculated event rate of electronic recoil in the same detector configuration is reduced by about $25\%$. We present in this paper the electronic recoil rate spectrum in the energy window of 100 eV - 30 keV with the standard per ton per year normalization for xenon detectors, and discuss its implication for low energy solar neutrino detection (as the signal) and WIMP search (as a source of background).