Electromagnetic properties of neutrinos from scattering on bound electrons in atom

TL;DR

This paper investigates how the electromagnetic properties of neutrinos affect their scattering on bound electrons in atoms, analyzing implications for experimental data and setting bounds on neutrino characteristics.

Contribution

It introduces the consideration of atomic nucleus recoil in neutrino-electron scattering and applies this to XENON1T data to derive bounds on neutrino magnetic moments and charge radius.

Findings

Bounds on neutrino magnetic moment: |f_{αβ}| ≤ 0.86×10^{-7} μ_B

Charge radius bound: |r̃| < 4.30×10^{-17} cm

Constraints on millicharge in the r̃^2-ε parameter space

Abstract

We consider the effects of bound atomic electrons scattered by solar neutrinos due to the electromagnetic properties of neutrinos. This necessiate considering the recoil of atomic nucleus, which should be considered in the momentum conservation, but that effect to the energy conservation is negligible. This effect changes the kinematic behavior of the scattered electron compared to that scattered on free electrons. We apply this effect to the recent XENON1T data, but the bounds obtained from this is not very restrictive. We obtained the bounds: the (transition) magnetic moment $|f_{\alpha\beta}|\le 0.86\times 10^{-7}$ (times the electron Bohr magneton) and the charge radius $|\tilde{r}|< 4.30\times 10^{-17\,}{\rm cm}$. For a non-vanishing millicharge ($\varepsilon$), the allowed bound is shown in the $\tilde{r}^2-\varepsilon$ plane.