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 \(B \rightarrow X^{}_{s} \gamma \), and exclusive radiative decays \(B \rightarrow K^{*} \gamma \) and \(B \rightarrow K^{0}_{S} \eta \gamma \). A lepton-flavor dependent measurements of angular observables for the decays \(B \rightarrow K^{*} \ell \ell \) 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 \(B^{0} \rightarrow K^{*0} \mu ^{\pm } e^{\mp }\) are searched for at Belle, and stringent limits on their branching fractions are set. The BaBar experiment has searched for the decay \(B^{+} \rightarrow K^{+} \tau ^{+} \tau ^{-}\), which comprises third generation of the lepton family. The decays \(B \rightarrow h \nu \bar{\nu }\) are searched for at Belle and obtained upper limits for these decays are close to the standard model predictions.