Form Factor $A_0(q^2)$, Non Leptonic $D(B)\to PV$ Transitions and Rare $B\to K^{\ast }\gamma$ Decays

P. Colangelo, F. De Fazio, P. Santorelli

We use three-point function QCD sum rules to calculate the form factor $A_0(q^2)$ appearing in the matrix element of the flavour-changing axial current between the $D(B)$ state an…