New bounds on neutrino electric millicharge from GEMMA experiment on neutrino magnetic moment

TL;DR

This paper derives new, more stringent bounds on the neutrino electric millicharge using GEMMA experiment data, improving upon previous limits by analyzing the neutrino magnetic moment and cross section contributions.

Contribution

It provides the first direct experimental upper bound on neutrino millicharge based on GEMMA data, refining previous indirect limits.

Findings

New upper bound on neutrino millicharge: < 2.7 x 10^{-12} e_0

Confirmation of bounds through statistical analysis of GEMMA data

Improved constraints compared to previous TEXONO experiment results

Abstract

Using the new limit on the neutrino anomalous magnetic moment recently obtained by GEMMA experiment we get an order-of-magnitude estimation for possible new direct upper bound on the neutrino electric millicharge $\mid q_{\nu} \mid \sim 1.5 \times 10^{-12} e_0$ ($e_0$ is the absolute value of the electron charge) by comparing the neutrino magnetic moment and millicharge contributions to the total cross section at the electron recoil energy threshold of the experiment. This estimation is confirmed by the performed analysis of the GEMMA data using established statistical procedures and a new direct bound on the neutrino millicharge absolute value $\mid q_{\nu} \mid < 2.7 \times 10^{-12} e_0 \ (90\% CL)$ is derived. This limit is more stringent than the previous one obtained from the TEXONO reactor experiment data that is included to the Review of Particle Properties 2012.