Hard bremsstrahlung for the production of prompt photons

Abstract

The analytical calculation of helicity amplitudes for hard photon and gluon bremsstrahlung radiation are described using the spinor formalism for processes of the type $\bar{q} q \to g \gamma$ and $q g \to q \gamma$. The presented amplitudes are expressed in terms of field strength bivectors, with allowance for the dependence on the helicities and masses of all particles. Numerical calculations have been performed for the quark-antiquark annihilation process $\bar{c}c$ at the center-of-mass energies of 24, 91, and 500 GeV, considering various combinations of helicities of the quarks and the photon in the final state. This study is part of the ongoing development of theoretical support, based on the SANC system, for the analysis of polarized observables in proton collisions at the NICA collider.