Study of B -> X gamma Decays and Determination of |V_td/V_ts|

TL;DR

This study measures the branching fractions of B->X gamma decays and determines the ratio |V_td/V_ts|, providing insights into quark flavor transitions and testing the Standard Model predictions.

Contribution

It presents the first measurement of the ratio |V_td/V_ts| using exclusive B->X gamma decays with a large data sample, improving precision over previous methods.

Findings

Branching fraction for b->d gamma: (9.2 +/- 2.0 +/- 2.3) x 10^-6

Branching fraction for b->s gamma: (23.0 +/- 0.8 +/- 3.0) x 10^-5

|V_td/V_ts| = 0.199 +/- 0.022 +/- 0.024 +/- 0.002

Abstract

Using a sample of 471 million BBbar events collected with the BaBar detector, we study the sum of seven exclusive final states B->X_s(d) gamma, where X_s(d) is a strange (non-strange) hadronic system with a mass of up to 2.0GeV/c^2. After correcting for unobserved decay modes, we obtain a branching fraction for b->d gamma of (9.2 +/- 2.0(stat.) +/- 2.3(syst.))x10^-6 in this mass range, and a branching fraction for b->s gamma of (23.0 +/- 0.8(stat.) +/- 3.0(syst.))x10^-5 in the same mass range. We find BF(b->dgamma) / BF(b->sgamma) = 0.040 +/- 0.009(stat.) +/- 0.010(syst.), from which we determine |V_td/V_ts|=0.199 +/- 0.022(stat.) +/- 0.024(syst.) +/- 0.002(th.).