# The 21st International Workshop on Neutrinos from Accelerators (NUFACT2019)

Aug 25 – 31, 2019
The Grand Hotel Daegu
Asia/Seoul timezone

## Searches for LFV and LNV at Belle II

Aug 30, 2019, 3:15 PM
25m
Maple Hall (LL/B1F) (The Grand Hotel Daegu)

### Maple Hall (LL/B1F)

#### The Grand Hotel Daegu

Oral Presentation

### Description

The Belle II experiment is a substantial upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric $e^+ e^-$ collider. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run and main operation of SuperKEKB has started in March 2019. Belle II has a broad $\tau$ physics program, in particular in searches for lepton flavor and lepton number violations (LFV and LNV), benefiting from the large cross section of the pairwise $\tau$ lepton production in $e^+ e^-$ collisions. We expect that after 5 years of data taking, Belle II will be able to reduce the upper limits on LF and LN violating $\tau$ decays by an order of magnitude. Any experimental observation of LFV or LNV in $\tau$ decays constitutes an unambiguous sign of physics beyond the Standard Model, offering the opportunity to probe the underlying New Physics. In this talk we will review the $\tau$ lepton physics program of Belle II.

Working Group WG4 : Muon Physics

### Primary authors

Ida Peruzzi (Laboratori Nazionali di Frascati dell'INFN)