A novel approach to cosmological fermion production

Abstract

This work extends a recent approach to gravitational particle production in asymptotically flat spacetimes, originally applied to scalar particles, to explore the cosmological production of Dirac fermions. This method avoids the necessity of solving the equation of motion by examining monodromies around singular points in the equations. We derive a general expression for the amount of spin-1/2 particle production, and elucidate to which scale factors it applies. In contrast to the scalar case, which exhibits three regimes, Dirac fermions present a single regime of production. Simple scale factor examples are examined, recovering easily all known results and producing new ones.