Fermion helicity flip and fermion oscillation induced by dynamical torsion field

Abstract

We show that in theories of gravitation based in affine geometries the torsion field, that takes a dynamical character, produces the non-conservation of the helicity of fermion particles (spin precession). Such effect is related to the torsion vector hμ (the dual of totally antisymmetric torsion field). The oscillation of fermion fields (e.g., Majorana neutrinos) in the presence of the dynamical torsion field also is computed showing that such oscillation depends on the zero component of hμ. This fact is in a sharp contrast with earlier reference (Capozziello S. et al., Europhys. Lett., 46 (1999) 710) were the torsion is a background (non-dynamical) being its dual a null vector. Cosmological implicancies of this research are discussed in the context of previous results of the authors where group theoretical features of the underlying theory and the relation torsion-dark matter field were considered.