Exclusive Measurements of b -> s gamma Transition Rate and Photon Energy Spectrum

TL;DR

This paper reports a precise measurement of the $b\rightarrow s\gamma$ transition rate and photon energy spectrum using data from the BABAR detector, providing insights into heavy-quark parameters and testing the Standard Model.

Contribution

It presents the first measurement of the inclusive $b\rightarrow s\gamma$ branching fraction and photon spectrum moments using 38 exclusive final states with improved accuracy.

Findings

Inclusive branching fraction $(3.29\pm 0.19\pm 0.48)\times 10^{-4}$

First and second moments of photon energy spectrum measured

Extracted heavy-quark parameters $m_b$ and $\mu_\pi^2$

Abstract

We use 429 fb$^{-1}$ of $e^+e^-$ collision data collected at the $\Upsilon(4S)$ resonance with the BABAR detector to measure the radiative transition rate of $b\rightarrow s\gamma$ with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be $\mathcal{B}(\bar B \rightarrow X_{s}\gamma)=(3.29\pm 0.19\pm 0.48)\times 10^{-4}$ where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best fit values for the heavy-quark parameters, $m_{b}$ and $\mu_{\pi}^{2}$, in the kinetic and shape function models.