A study of B → K∗ℓ+ℓ− decay in soft-collinear effective theory

A brief account of the study of rare B decay B→K∗ℓ+ℓ− using soft-collinear effective theory (SCET) from [A. Ali, G. Kramer and G.-h. Zhu, Euro. Phys. J. C (in press) [hep-ph/0601034]] is presented here. The main result of this study is a factorization formula, derived to leading power in 1/mb but valid to all orders in αs. For phenomenological application, the decay amplitude including order αs corrections is calculated and the logarithms resummed by evolving the matching coefficients from the hard scale O(mb) down to the scale . The partially integrated branching ratio in the range is calculated to be . For the zero-point of the forward-backward asymmetry in the standard model, one gets . The scale dependence of is improved compared to the earlier estimates of the same.