Measurement of B-->K*gamma Branching Fractions and Charge Asymmetries

TL;DR

This paper reports precise measurements of the branching fractions and charge asymmetries for B meson decays to K* gamma, providing important tests of the Standard Model and constraints on CP violation.

Contribution

The study provides the first measurements of these branching fractions and charge asymmetries using a large data sample from the BABAR detector.

Findings

Branching fraction for B^0→K*0γ: (4.23±0.40±0.22)×10^−5

Branching fraction for B^+→K*+γ: (3.83±0.62±0.22)×10^−5

Charge asymmetry constrained between -0.170 and 0.082 at 90% C.L.

Abstract

The branching fractions of the exclusive decays $B^0\to K^{*0}\gamma$ and $B^+ \to K^{*+}\gamma$ are measured from a sample of $(22.74\pm 0.36)\times 10^6$ $B\bar B$ decays collected with the BABAR detector at the PEP II asymmetric $e^{+}e^{-}$ collider. We find ${\cal B}(B^0\to K^{*0}\gamma) = (4.23\pm 0.40({\rm stat.})\pm 0.22({\rm sys.}))\times 10^{-5}$, ${\cal B}(B^+\to K^{*+}\gamma) = (3.83\pm 0.62({\rm stat.})\pm 0.22({\rm sys.}))\times 10^{-5}$ and constrain the CP-violating charge asymmetry to be $-0.170 < A_{CP}(B \to K^*\gamma) < 0.082$ at 90% C.L.