vertical bar Vtd/Vts vertical bar from B→Vγ

The dominant theoretical uncertainty in extracting vertical bar Vtd/Vts vertical bar from the ratio of branching ratios R≡B(B→(ρ,ω)γ)/B(B→K*γ) is given by the ratio of form factors ξ≡T1B→K*(0)/T1B→ρ(0). We re-examine ξ in the framework of QCD sum rules on the light-cone, taking into account hitherto neglected SU(3)-breaking effects. We find ξ 1.17±0.09. Using QCD factorisation for the branching ratios, and the current experimental average for R quoted by HFAG, this translates into vertical bar Vtd/Vts vertical barHFAG 0.179±0.022(exp)±0.014(th). This result agrees, within errors, with that obtained from the Standard Model unitarity triangle based on tree-level-only processes and with vertical bar Vtd/Vts vertical bar inferred from the two-sided bound on Δms reported recently by the D0 collaboration