Neutrino propagation in matter with general interactions - art. no. 093008

We present a general analysis of the effective potential for neutrino propa gation in matter, assuming a generic set of Lorentz invariant non-derivativ e interactions. We find that in addition to the known vector and axial vect or terms, in a polarized medium also tensor interactions can play an import ant role. We compute the effective potential arising from a tensor interact ion. We show that the components of the tensor potential transverse to the direction of the neutrino propagation can induce a neutrino spin flip, simi lar to the one induced by a transverse magnetic field. [S0556-3821(99)00219 -2].