SU(3) breaking of leading-twist K and K* distribution amplitudes -: a reprise

We present new QCD sum rules for the leptonic decay constants f(K) and f(K)(parallel to.perpendicular to) of the K and K*, respectively, and the SU(3) breaking quantities a(1)(parallel to.perpendicular to)(K*), the first Gegenbauer-moments of the leading-twist distribution amplitudes of K*, including SU(3) breaking effects up to second order; we also confirm existing results for the sum rule for a(1)(K). The results for f(K) and f(K)(parallel to) agree with experiment. Our predictions for f(K)(perpendicular to) and a(1)(parallel to.perpendicular to)(K*) 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. (c) 2005 Elsevier B.V. All rights reserved.