A measurement of the tau mass and the first CPT test with tau leptons

TL;DR

This paper reports a precise measurement of the tau lepton mass and a test of CPT invariance by comparing positive and negative tau masses, finding no significant difference within experimental uncertainty.

Contribution

It provides the first CPT test with tau leptons by comparing their masses, and measures the tau mass with improved precision from Z0 decay data.

Findings

Tau mass measured as 1775.1 MeV with combined uncertainty.

No significant CPT violation observed in tau mass comparison.

Mass difference below 3.0 x 10^-3 at 90% confidence level.

Abstract

We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV using tau pairs from Z0 decays. To test CPT invariance we compare the masses of the positively and negatively charged tau leptons. The relative mass difference is found to be smaller than 3.0 10^-3 at the 90% confidence level.