On gamma_5 in higher-order QCD calculations and the NNLO evolution of the polarized valence distribution
arXiv:1506.04517
Abstract
We discuss the prescription for the Dirac matrix gamma_5 in dimensional regularization used in most second- and third-order QCD calculations of collider cross sections. We provide an alternative implementation of this approach that avoids the use of an explicit form of gamma_5 and of its (anti-) commutation relations in the most important case of no more than one gamma_5 in each fermion trace. This treatment is checked by computing the third-order corrections to the structure functions F_2 and g_1 in charged-current deep-inelastic scattering with axial-vector couplings to the W-bosons. We derive the so far unknown third-order helicity-difference splitting function Delta P_ns^(2)s that contributes to the next-to-next-to-leading order (NNLO) evolution of the polarized valence quark distribution of the nucleon. This function is negligible at momentum fractions x >~ 0.3 but relevant at x << 1.
11 pages, Latex, 2 figures. FORM and Fortran files of the main results available with the source
References in corpus (2)
Cited by in corpus (7)
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