The 18th International Workshop on Tau Lepton Physics (TAU2025)

Averages of tau branching fractions and combined tau lepton-flavour-violating branching fractions limits by HFLAV

Not scheduled

20m

Amphitheatre Gastaut (Marseille)

Talk Tau properties and SM Plenary session

Speaker

Alberto Lusiani (Scuola Normale Superiore and INFN, sezione di Pisa)

Description

In the Tau section of the HFLAV 2023 report (arXiv:2411.18639 [hep-ex]) we present an improved global fit of the tau branching fractions and new combinations of tau lepton-flavour-violating (LFV) upper limits. The branching fraction fit includes recent measurements and furthermore since this report features nuisance fit parameters. The HFLAV fit is now identical to the fit that HFLAV uses, with the unitarity constraint, to provide the Tau fit results for the PDG. The lepton flavour universality tests and the $|V_{us}|$ calculations with tau measurements are updated. A new lattice QCD calculation is used to update $|V_{us}|$ using the inclusive branching fraction to strange final states. A new method is used to combine the LFV limits, by averaging the corresponding raw branching fraction measurements and computing limits using the averaged branching fraction.