Scattering amplitudes with massive fermions using BCFW recursion

Abstract

We study the QCD scattering amplitudes for \(\bar{q}q\to{gg}\) and \(\bar{q}q\to{ggg}\) where q is a massive fermion. Using a particular choice of massive fermion spinor we derive compact expressions for the partial spin amplitudes for the 2→2 process. We then investigate the corresponding 2→3 amplitudes using the BCFW recursion technique. For the helicity conserving partial amplitudes we present new expressions, but we were unable to treat the helicity-flip amplitudes recursively, except for the case where all the gluon helicities are the same. We therefore evaluate the remaining partial amplitudes using standard Feynman diagram techniques.