Neutrino spin flip around a Schwarzschild black hole

We propose a new approach to the study of spin-flip probability for massive Dirac neutrinos orbiting around a Schwarzschild black hole, recently considered by Dvornikov ( 2006 Int. J. Mod. Phys. 15 1017). Inspired by the paper by Papini and Lambiase ( 2002 Phys. Lett. A 294 175), we employ a reference frame comoving with the particle in the curved spacetime background. Using a suitable tetrad adapted to a comoving observer, we discuss the gravito-inertial effects ( curvature plus spin rotation or Mashhoon effect) on the massive neutrino spin-flip probability. At variance with some recent claims, we find non-null results, in very good agreement with those obtained in [ 19], although through quite a different approach. Such results suggest a sort of competition between gravity and inertia. Taking into account the possible anomalous magnetic moment. of a massive Dirac neutrino, we also briefly consider the interplay between gravito-inertial and magnetic effects, in the presence of some external strong magnetic field in the Schwarzschild geometry ( which is believed to be a typical scenario in the case of Active Galactic Nuclei ( AGN) or neutron stars). We find some evidence that the actual poor knowledge about the bounds on. cannot rule out the possibility of some relevant competition between the two effects.