A Biased Review of Tau Neutrino Mass Limits

TL;DR

This paper reviews tau neutrino mass limits from experiments, questions the statistical methods used to derive these limits, and proposes a more robust approach for future measurements.

Contribution

It critically examines existing tau neutrino mass limits, challenges the statistical assumptions behind them, and offers a new method for more reliable limit estimation.

Findings

Current limits are overly consistent, possibly indicating underestimated uncertainties.

Standard maximum likelihood estimators may have questionable statistical properties in this context.

A new prescription for deriving more robust tau neutrino mass limits is proposed.

Abstract

After a quick review of astrophysically relevant limits, I present a summary of MeV scale tau neutrino mass limits derived from accelerator based experiments. I argue that the current published limits appear to be too consistent, and that we therefore cannot conclude that the tau neutrino mass limit is as low as usually claimed. I provide motivational arguments calling into question the assumed statistical properties of the usual maxumum likelihood estimators, and provide a prescription for deriving a more robust and understandable mass limit.