Xiao-Gang He: Majorana Phase and Matter Effects in Neutrino Chiral Oscillation
Due to finite masses and mixing, for neutrinos propagate in space-time, there is a transition between left- and right- handed neutrinos, termed chiral oscillation, besides the usual oscillation governed by the Dirac equation. The probability of chiral oscillation is suppressed by a factor m2/E2. For non-relativistic neutrinos, this effects can be significant. In matter, the equation of motion is modified. Neutrinos produced in weak interaction after passing through the matter, the effective energies are split into two different ones depending on the helicity of the neutrino. This results in different oscillation behavior for neutrinos with different helicity, in particular there is a resonant effect for the left-handed neutrino of negative helicity into right-handed neutrino of negative helicity. Chiral oscillation pattern also depends on Majorana phases in Seesaw models.