Measurement of B→Xγ Decays and Determination of |Vtd/Vts|

Abstract

Using a sample of 383 × 10 6 B ¯¯¯ B events collected by the BABAR experiment, we measure sums of seven exclusive final states B → X d ( s ) γ , where X d ( X s ) is a nonstrange (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 → d γ of ( 7.2 ± 2.7 ( stat ) ± 2.3 ( syst ) ) × 10 − 6 . Taking the ratio of X d to X s we find Γ ( b → d γ ) / Γ ( b → s γ ) = 0.033 ± 0.013 ( stat ) ± 0.009 ( syst ) , from which we determine | V t d / V t s | = 0.177 ± 0.043 .