Contributor info: Dr Michel Enrique Hernandez Villanueva

Michel Hernández Villanueva

SciPost Phys. Proc. 16, 015 (2025) · published 14 July 2025 | Toggle abstract · pdf

Belle II is a major upgrade of the Belle detector, operating at the SuperKEKB asymmetric-energy $e^+e^-$ collider with a design luminosity of 8×$10^{35}$ cm$^{-2}$s$^{-1}$. To date, the detector has recorded over 200 fb$^{-1}$ of data and aims to collect 50 ab$^{-1}$, a factor of 50 more than its predecessor. Belle II has a broad $\tau$ physics program, from high-precision measurements of Standard Model parameters to searches of new non-Standard-Model interactions. In this work, we review the status of the Belle II experiment and the prospects for the measurement of the $\tau$ lepton mass and lifetime, which are fundamental inputs in tests of LFU violation.

Michel Hernandez Villanueva on behalf of the Belle II collaboration

SciPost Phys. Proc. 1, 003 (2019) · published 18 February 2019 | Toggle abstract · pdf

The Belle II experiment is an upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric $e^+e^-$ collider. The accelerator has already successfully completed the first phase of commissioning and first electron positron-collisions in Belle II were observed in April 2018. The design luminosity of SuperKEKB is 8x10$^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than the Belle experiment. Belle II has a broad program of $\tau$ physics, in particular, precision measurements of Standard Model parameters and searches of 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. In this talk, we will review the $\tau$ lepton physics program of Belle II.