A New Upper Limit for the Tau-Neutrino Magnetic Moment

TL;DR

This paper reports a new upper limit on the tau-neutrino magnetic moment using a novel neutrino beam with a tau-neutrino component, based on observed neutrino-electron interactions.

Contribution

It introduces the first measurement of tau-neutrino magnetic moment using a prompt neutrino beam with tau-neutrino identification.

Findings

Observed one neutrino-electron interaction event.

Expected background was 2.3 events.

Set an upper limit of 3.9x10^-7 Bohr magnetons.

Abstract

Using a prompt neutrino beam in which a nu_tau component was identified for the first time, the nu_tau magnetic moment was measured based on a search for an anomalous increase in the number of neutrino-electron interactions. One such event was observed when 2.3 were expected from background processes, giving an upper 90% confidence limit of 3.9x10^-7 Bohr magnetons.