# EPS-HEP2019

Jul 10 – 17, 2019
Ghent
Europe/Brussels timezone

## Measurement of the branching fractions ${\cal{B}}(\tau \to K\,n\pi^0 \nu)$, $n=0,1,2,3$, and ${\cal{B}}(\tau \to \pi\,n\pi^0 \nu)$, $n=3,4$

Jul 13, 2019, 12:20 PM
20m
Campus Ledeganck - Aud. 5 (Ghent)

### Campus Ledeganck - Aud. 5

#### Ghent

Parallel talk Flavour Physics and CP Violation

### Speaker

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

### Description

We report the measurements of the branching fractions of the decays $\tau \to K\,n\pi^0 \nu$, $n=0,1,2,3$, and $\tau\to \pi\, n\pi^0 \nu$, $n=3,4$. The measurements are based on a data sample of 435 million tau pairs produced in $e^+e^-$ collisions at and near the $Y(4S)$ peak and collected with the BABAR detector in $1999-2008$. Additional systematic studies have been completed after the presentation of the preliminary results. Most measurements are substantial improvements over previous measurements and ${\cal{B}}(\tau \to \pi\,4\pi^0 \nu)$, is measured for the first time. These measurements improve the determination of $|V_{us}|$ from the branching fraction $\tau^{-} \to X_{s}^{-} \nu_\tau$ computed as the sum of all measured exclusive modes, with a method based on finite-energy QCD sum rules.

### Primary authors

Fabio Anulli (Sapienza Universita e INFN, Roma I (IT)) Alberto Lusiani (Scuola Normale Superiore and INFN, sezione di Pisa)