Counting contact terms in $B\to V\gamma$ decays

Abstract

We clarify the origin and cancellation of contact terms in the weak annihilation amplitudes contributing to $B\to V\gamma$. It is demonstrated that the photon emission from the final-state quarks vanishes in the chiral limit of massless quarks. The contact terms in the QCD light-cone sum rule evaluation of the weak annihilation amplitudes are also discussed.

Comments: 16 pages, 2 figures, Latex, ws-p8-50x6-00.cls, to be published in Sergei Matinian Festschrift ``From Integrable Models to Gauge Theories.'', Eds. V. Gurzadyan, A. Sedrakyan, World Scientific, 2002