Measurements of branching fractions for B+→ρ+γ, B0→ρ0γ, and B0→ωγ

Abstract

We present branching fraction measurements for the radiative decays B + → ρ + γ , B 0 → ρ 0 γ , and B 0 → ω γ . The analysis is based on a data sample of 465 × 10 6 B ¯¯¯ B events collected with the BABAR detector at the PEP-II asymmetric-energy B Factory located at the Stanford Linear Accelerator Center. We find B ( B + → ρ + γ ) = ( 1.20 + 0.42 − 0.37 ± 0.20 ) × 10 − 6 , B ( B 0 → ρ 0 γ ) = ( 0.97 + 0.24 − 0.22 ± 0.06 ) × 10 − 6 , and a 90% C.L. upper limit B ( B 0 → ω γ ) < 0.9 × 10 − 6 , where the first error is statistical and the second is systematic. We also measure the isospin-violating quantity Γ ( B + → ρ + γ ) / 2 Γ ( B 0 → ρ 0 γ ) − 1 = − 0.43 + 0.25 − 0.22 ± 0.10 .