出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The calculation of massive 2–loop operator matrix elements, required for the higher order Wilson
coefficients for heavy flavor production in deeply inelastic scattering, leads to new types of
multiple infinite sums over harmonic sums and related functions, which depend on the Mellin
parameter N. We report on the solution of these sums through higher order difference equations
using the summation package Sigma.
