Two-Loop Massive Operator Matrix Elements for Unpolarized Heavy Flavor Production to O(ǫ)

We calculate the O(2 s ) massive operator matrix elements for the twist–2 operators, which contribute to the heavy flavor Wilson coefficients in unpolarized deeply inelastic scattering in the region Q2 ≫ m2, up to the O(") contributions. These terms contribute through the renormalization of the O(3´s ) heavy flavor Wilson coefficients of the structure function F2(x,Q2). The calculation has been performed using light–cone expansion techniques with-out using the integration-by-parts method. We represent the individual Feynman diagrams by generalized hypergeometric structures, the "–expansion of which leads to infinite sums depending on the Mellin variable N. These sums are finally expressed in terms of nested harmonic sums using the general summation techniques implemented in the Sigma package.