Bounding heavy meson form factors using inclusive sum rules

Abstract

We utilize inclusive sum rules to construct both upper and lower bounds on the form factors for B → D , D ∗ , ϱ, π, ω, K and K ∗ semi-leptonic and radiative decays. We include the leading nonperturbative 1 E corrections and point out cases when α s corrections are equally important. We compute the α s correction to the lower bound on the B → D ∗ form factor f( w) at zero recoil, thereby constraining its normalization f(1) to within 6–8% of the upper bound. We show that the B → ϱ form factor α + is suppressed at small momentum transfer by either a factor of 1 E or α s . These bounds can be used to rule out phenomenological models as well as to determine values for the CKM matrix elements once radiative corrections are included.