# EPS HEP 2015

22-29 July 2015
Europe/Vienna timezone

## Leptonic and Radiative B meson decays at Belle

Jul 23, 2015, 10:15 AM
15m
HS21

### HS21

talk Flavour Physics and Fundamental Symmetries

### Speaker

Paoti Chang (National Taiwan University)

### Description

We will present new results on leptonic and radiative leptonic decays. Purely leptonic B meson decays, $B \to \ell \nu$, are helicity-suppressed in the Standard Model (SM), and while more challenging for the extraction of the CKM matrix element $|V_{ub}|$, they are excellent probes of models beyond the SM. The decay $B \to \ell \nu\gamma$ is not affected by this suppression and gives access to $\lambda_B$, a parameter used to describe charmless hadronic B decays into two mesons in the QCD factorization (QCDF) scheme. We also report new results on exclusive radiative decays, $B_s \to \gamma\gamma$, $B_s \to \phi\gamma$, and $B_d \to \phi\gamma$, which proceed via flavour-changing-neutral-current transitions $b \to s \gamma \gamma$, $b \to s\gamma$ and $b \to d\gamma$, respectively. These modes are highly sensitive to new physics. All results presented are based on the full data sample accumulated by the Belle experiment at the KEKB asymmetric energy e+e− collider at KEK, Japan.