Measurement of $B \to X \gamma$ Decays and Determination of $|V_{td}/V_{ts}|$

TL;DR

This study measures the branching fractions of specific $B$ meson decays involving photons, providing a new determination of the ratio of CKM matrix elements $|V_{td}/V_{ts}|$ with implications for understanding quark flavor transitions.

Contribution

It presents the first measurement of the sum of seven exclusive $B o X_{d(s)} o ext{hadronic} imes ext{gamma}$ decay modes in a specific mass range, and extracts $|V_{td}/V_{ts}|$ from these data.

Findings

Branching fraction for $b o d ext{ gamma}$ is $(7.2 extpm 2.7 ext{(stat.)} extpm 2.3 ext{(syst.)}) imes 10^{-6}$.

Ratio $rac{ ext{Gamma}(b o d ext{ gamma})}{ ext{Gamma}(b o s ext{ gamma})} = 0.033 extpm 0.013 ext{(stat.)} extpm 0.009 ext{(syst.)}$.

Determined $|V_{td}/V_{ts}|=0.177 extpm 0.043$.

Abstract

Using a sample of 383 million $B\bar{B}$ events collected by the $BaBar$ experiment, we measure sums of seven exclusive final states $B\to X_{d(s)}\gamma$, where $X_d$($X_s$) is a non-strange (strange) charmless hadronic system in the mass range $0.6-1.8$ GeV$/c^2$. After correcting for unmeasured decay modes in this mass range, we obtain a branching fraction for $b \to d \gamma$ of $(7.2\pm 2.7(stat.)\pm 2.3(syst.))\times 10^{-6}$. Taking the ratio of $X_d$ to $X_s$ we find $\Gamma(b \to d \gamma)/\Gamma(b \to s \gamma) = 0.033 \pm 0.013 (stat.) \pm 0.009 (syst.),$ from which we determine $|V_{td}/V_{ts}|=0.177\pm 0.043$.