  New f(R,T) model of gravitation, introduced previously by the author, is
considered. It is based on an affine geometrical construction in which the
torsion is a dynamical field, the coupling is minimal and the theory is Lorentz
invariant by construction. It was shown that the Dirac equation emerges from
the same space time and acquires a modification (coupling-like) of the form
{\gamma}^{{\alpha}}j((1-d)/d){\gamma}h_{{\alpha}}, with h_{{\alpha}} the
torsion axial vector, j a parameter of pure geometrical nature and d, the
spacetime dimension. In the present work it is shown that this interaction
produces a mechanism of spin (helicity) flipping, with its consequent weak
symmetry violation. The cross section of this process is explicitly calculated
and a logaritmical energy dependence (even at high energies) is found. This
behavior is reminiscent of similar computations made by Hans Bethe in the
context of neutrino astrophysics. These results are applied to the solar
neutrino case and compared with similar results coming from a gravitational
model with torsion of string theory type and within the standard model context
respectively.
