Renormalized sum rules for structure functions of heavy mesons decays

الأصل · EN

We consider properties of the structure functions of inclusive heavy meson decays B→ Xc and treat the c quark mass as a free parameter. We show that in two extreme cases of heavy and light c quark the structure functions of heavy--heavy and heavy--light transitions are given by a Fourier transform of the matrix elements of Wilson lines containing a time--like and a light--like segment, correspondingly. Using the renormalization properties of Wilson lines we find the dependence of the structure functions on the factorization scale, the structure function of heavy--heavy transition is renormalized multiplicatively while that of heavy-light transition obeys the GLAP--type evolution equation. We propose a generalization of the sum rules for the moments of the structure functions (Bjorken, Voloshin, and the ``third'' sum rules) with a soft exponential factorization cut--off, which correctly incorporates both perturbative and nonperturbative effects. We analyze nonperturbative corrections by first considering infrared renormalon contributions to the Wilson lines. Uncertainties induced by the leading renormalon pole at u=12 are exactly cancelled by the similar uncertainty in the heavy quark pole mass. The leading nonperturbative corrections associated with the next renormalon at u=1 are parameterized by the matrix element μπ² which is proportional to the heavy quark kinetic energy.