SU(3) Breaking of Leading--Twist K and K* Distribution Amplitudes - a Reprise

Abstract

We review the status of the leptonic decay constants f_K and f_K^{\parallel,\perp} of the K and K*, respectively, and the SU(3) breaking quantities a_1(K) and a_{1}^{\parallel,\perp}(K*), the first Gegenbauer-moments of the leading-twist distribution amplitudes of K and K*. We obtain new predictions from QCD sum rules which are relevant for the calculation of K and K* form factors, for instance T_1^{B->K*}, which determines the decay B -> K* gamma, and for QCD factorisation calculations of nonleptonic B decays into strange mesons, for instance B -> K pi.