Radiative and electroweak penguin decays at $e^{+}e^{-}$ $B$-factories

Abstract

$B$-meson decays involving radiative and electroweak penguin processes are sensitive probes to new physics beyond the standard model. The Belle experiment recently reported measurements of the inclusive radiative decay $B \to X^{}_{s} \gamma$, and exclusive radiative decays $B \to K^{\ast} \gamma$ and $B \to K^{0}_{S} \eta \gamma$. A lepton-flavor dependent measurements of angular observables for the decays $B \to K^{\ast} \ell \ell$ by Belle hinted at possible deviation from lepton-flavor-universality. Any departure from lepton flavor universality is essentially accompanied by lepton flavor violation. Recently, lepton-flavor-violating decays $B^{0} \to K^{\ast 0} \mu ^{\pm} e^{\mp}$ are searched at Belle, and stringent limits on their branching fractions are set. The BaBar experiment has searched for the decay $B^{+} \to K^{+} \tau^{+} \tau^{-}$, which comprises third generation of the lepton family. The decays $B \to h \nu \bar{\nu}$ are searched at Belle and obtained upper limits for these decays are close to the standard model predictions.