Implication of the B→(ρ, ω)γ branching ratios for the CKM phenomenology

We study the implication of the recent measurement by the BELLE Collaboration of the averaged branching fraction (B) over bar (exp)[B --> (rho, omega)gamma] = (1.8(-0.5)(+0.6) +/- 0.1) x 10(-6) for the CKM phenomenology. Combined with the averaged branching fraction (B) over bar (exp)(B --> K*gamma) = (4.06 +/- 0.26) x 10(-5) measured earlier, this yields (R) over bar (exp)[(rho, omega)gamma/K*gamma] = (4.2 +/- 1.3)% for the ratio of the two branching fractions. Updating earlier theoretical analysis of these decays based on the QCD factorization framework, and constraining the CKM-Wolfenstein parameters from the unitarity fits, our results yield (B) over bar (th)[B --> (rho, omega)gamma] = (1.38 +/- 0.42) x 10(-6) and (R) over bar (th)[(rho, omega)gamma/K*gamma] = (3.3 +/- 1.0)%, in agreement with the BELLE data. Leaving instead the CKM-Wolfenstein parameters free, our analysis gives (at 68% C.L.) 0.16 less than or equal to \V-td/V-ts\ less than or equal to 0.29, which is in agreement with but less precise than the indirect CKM-unitarity fit of the same, 0.18 less than or equal to \V-td/V-ts\ less than or equal to 0.22. The isospin-violating ratio in the B --> rhogamma decays and the SU(3)-violating ratio in the B-d(0) --> (rho(0), omega)gamma decays are presented together with estimates of the direct and mixing-induced CP-asymmetries in the B --> (rho, omega)gamma decays within the SM. Their measurements will overconstrain the angle alpha of the CKM-unitarity triangle. (C) 2004 Elsevier B.V. All rights reserved.