Threshold resummation in B -> X(c)lv(l) decays

We compute the QCD form factor resumming threshold logarithms in B -> X-c + l + v(l) decays to next-to-leading logarithmic approximation. We present an interpolation formula including soft as well as collinear effects softened by the non-vanishing charm mass which, in the N-space, [GRAPHICS] the charm quark and reduces to the standard double-logarithmic function A(rho; alpha(S)) in the massless limit rho -> 0. The function B(alpha(S)) describes hard collinear emission off the charm quark, being the standardjet function. D(alpha(S)) and Delta(alpha(S)) describe soft radiation not collinearly enhanced off the beauty and the charm quark respectively. (c) 2007 Elsevier B.V. All rights reserved. RI Ricciardi, Giulia/H-3649-2011