# ICHEP 2020

28 July 2020 to 6 August 2020
virtual conference
Europe/Prague timezone

## Study of $B$ and $B_{s}$ Decays at Belle

28 Jul 2020, 16:15
15m
virtual conference

#### virtual conference

Talk 05. Quark and Lepton Flavour Physics

### Speaker

Nisar Nellikunnummel (BNL)

### Description

We present the study of $B_{s}$ decays using 121.4 fb$^{-1}$ of data collected at $\Upsilon(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy electron-positron collider. We search for $B_{s}\to \eta^{\prime} \eta$ and $B_{s}\to \eta^{\prime} K^{0}_{S}$, which are suppressed in the standard model (SM) and can receive contribution of physics beyond the SM. We also report the first model-independent measurement of B($B_{s}\to D_{s} X$) using $B_{s}$ semileptonic tagging; this is necessary for measuring absolute rates and branching fractions of other $B_{s}$ decays. In addition, we present precise measurements of the branching fraction and CP asymmetry in $B\to \phi \phi K$ decays using Belle data that corresponds to 772 million $B\overline{B}$ pairs. These decays are mediated by the $b\to s$ FCNC transition, where one can observe large CP violation due to interference of potential new-physics amplitudes appearing in the loop with the $b\to c$ tree-level transition of $B\to \eta_{c} K$, $\eta_{c}\to \phi \phi$.