  At the end of inflation, the coherent oscillations of the inflaton field may
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 evolution
of the inflaton and the Higgs fields after inflation induce a very different
production of fermions depending on whether they are coupled to the Higgs or to
the inflaton. For reasonable values of the model parameters, the fermion
production through parametric resonance can be very efficient. We study the
relative growth of the fermion and boson energy densities during preheating in
hybrid models. During the initial stage of preheating, fermion production
dominates the relative energy density, while the exponential growth of bosonic
modes soon takes over.
