Fermion production during preheating after hybrid inflation

At the end of inflation, the coherent oscillations of the inflaton field ma y resonantly amplify the long wavelength modes of both bosons and fermions coupled to it. We study the resonant production of both kinds of particles during preheating in a model of hybrid inflation. The coherent time evoluti on of the inflaton and the Higgs fields after inflation induce a very diffe rent production of fermions depending on whether they are coupled to the Hi ggs or to the inflaton. For reasonable values of the model parameters, the fermion production through parametric resonance can be very efficient. We s tudy the relative growth of the fermion and boson energy densities during p reheating in hybrid models. During the initial stage of preheating, fermion production dominates the relative energy density, while the exponential gr owth of bosonic modes soon takes over.