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 to D, D*, rho, pi, omega, K and K* semi-leptonic and radiative decays. We include the leading nonperturbative 1/E corrections and point out cases when alpha_s corrections are equally important. We compute the alpha_s correction to the lower bound on the B to 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 to rho form factor a_+ is suppressed at small momentum transfer by either a factor of 1/E or alpha_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.