On the conversion of mass eigenstates

Abstract

In this paper we consider a stable particle with flavor mixing. We demonstrate that incoherent conversion of heavy mass eigenstates into light ones and vice versa can occur, as a result of elastic scattering. This effect is nontrivial for non-relativistic particles, for which the standard flavor oscillation ceases rapidly due to incoherence. We also prove that if a heavy state is bound in a gravitational potential and a light state is unbound, the mass-state conversion can lead to gradual "evaporation" of the mixed particle from the potential. A number of implications, ranging from the cosmic neutrino background distortions to scenarios of cold dark matter evaporation from halos, are addressed.