  Non-thermal fermionic particle production is investigated in Einstein-Cartan
modified gravity with a modified Holst term and non-minimal couplings between
the spin connection and a fermion. By using the auxiliary field method, the
theory is rewritten into a pseudoscalar-tensor theory with Einstein-Hilbert
action and canonical kinetic and potential terms for a pseudoscalar field. The
introduced field is called Einstein-Cartan pseudoscalaron. If the potential
energy of the Einstein-Cartan pseudoscalaron dominates the energy density of
the early universe, it causes inflationary expansion. After the end of
inflation, the pseudoscalaron develops a large value and the non-minimal
couplings destabilize the vacuum. Evaluating the non-thermal fermionic particle
production process, we obtain the mass and the helicity dependences of the
produced particle number density. We show the model parameters to enhance the
preheating and reheating processes.
