Search for Radiative Penguin Decays B+→ρ+γ, B0→ρ0γ, and B0→ωγ

A search for the decays B→ρ(770)γ and B0→ω(782)γ is performed on a sample of 211×106 Υ(4S)→BB̅ events collected by the BABAR detector at the SLAC PEP-II asymmetric-energy e+e- storage ring. No evidence for the decays is seen. We set the following limits on the individual branching fractions: B(B+→ρ+γ)<1.8×10-6, B(B0→ρ0γ)<0.4×10-6, and B(B0→ωγ)<1.0×10-6 at the 90% confidence level. We use the quark model to limit the combined branching fraction B̅ [B→(ρ/ω)γ]<1.2×10-6, from which we determine a constraint on the ratio of Cabibbo-Kobayashi-Maskawa matrix elements |Vtd|/|Vts|.