Form factors and branching ratios of the FCNC $B \to a_1   \ell^{+}\ell^{-}$ decays
  We analyze the semileptonic $B \to a_1 \ell^+\ell^-$, $\ell=\tau, \mu, e$ transitions in the frame work of the three-point QCD sum rules in the standard model. These rare decays governed by flavor-changing neutral current transition of $b \to d$. Considering the quark condensate contributions, the relevant form factors as well as the branching fractions of these transitions are calculated. 
R. Khosravi
hep-ph