Form factor ${\mathit{A}}_0$(${\mathit{q}}^2$), nonleptonic D(B)→PV transitions, and rare B→${\mathit{K}}^{\mathrm{*}}$γ decays

We use three-point function QCD sum rules to calculate the form factor ${\mathit{A}}_0$(${\mathit{q}}^2$) appearing in the matrix element of the flavor-changing axial vector current between the D(B) state and a vector meson state. We describe the role of this form factor in nonleptonic D(B)→PV decays and analyze the light SU(3${)}_{\mathit{F}}$-symmetry-breaking effects. We also discuss a proposal to relate the branching ratio of B→${\mathit{K}}^{\mathrm{*}}$γ to the spectrum of the semileptonic B→ρlν decay.