Norihisa Watanabe
Articles written in Pramana – Journal of Physics
Volume 73 Issue 4 October 2009 pp 639-655
Application of FIRE for the calculation of photon matrix elements
The next-to-next-to-leading order (the order $\alpha \alpha_{s}^{2}$ ) corrections to the first moment of the polarized virtual photon structure function $g_{1}^{\gamma} (x, Q^{2}, P^{2})$ are studied in perturbative QCD for the kinematical region $\Lambda^{2} \ll P^{2} Q^{2}$, where $−Q^{2} (−P^{2})$ is the mass square of the probe (target) photon and 𝛬 is the QCD scale parameter. In order to evaluate the two-loop Feynman diagrams for the photon matrix element of the gluon operator, I apply the recently developed algorithm FIRE which reduces a complicated sum of scalar Feynman integrals to a linear combination of a few master integrals. The details of the calculation are presented.
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