  We study a class of early universe cosmological models based on
Einstein-Cartan gravity and including a higher derivative term corresponding to
a power of the Holst scalar curvature. The resulting effective action is
basically given by General Relativity and an additional neutral pseudoscalar
field (the pseudoscalaron), unequivocally related to the corresponding
components of the torsion, that necessarily acquire a dynamics. The induced
pseudoscalaron potential provides a realistic inflationary phase together with
a very rich postinflationary epoch, resulting by the coupling of the
pseudoscalaron to ordinary matter.
