The three channels of the process f_1 bar-f_1 H A --> 0 in the SANC framework

Abstract

In this paper we describe the implementation of the processes f_1 bar-f_1 H A --> 0 into the framework of SANC system. Here A stands for a photon and f_1 -- for a massless fermion whose mass is neglected everywhere besides arguments of logarithmic functions. The symbol --> 0 means that all 4-momenta flow inwards. The derived one-loop scalar form factors can be used for any cross channel after an appropriate permutation of their arguments s,t,u. We present the covariant and helicity amplitudes for all three possible cross channels. For checking of the correctness of the results first of all we observe the independence on the gauge parameters and the validity of Ward identity (external photon transversality), and, secondly, we make an extensive comparison with the other independent calculations.