  It is shown that if weak interactions can generate masses and polarize
matter, then the Cherenkov effect induced by these interactions appears. The
resonance ($v_\nu < c/n$) and the Cherenkov ($v_\nu > c/n$) effects are
competitive processes and at definite neutrino energies the resonance effect
will change to the Cherenkov effect and we obtain an excellent possibility of
estimating neutrino masses.
