On the Dynamics of Non-Relativistic Flavor-Mixed Particles
  Evolution of a system of interacting non-relativistic quantum flavor-mixed
particles is considered both theoretically and numerically. It was shown that
collisions of mixed particles not only scatter them elastically, but can also
change their mass eigenstates thus affecting particles' flavor composition and
kinetic energy. The mass eigenstate conversions and elastic scattering are
related but different processes, hence the conversion $S$-matrix elements can
be arbitrarily large even when the elastic scattering $S$-matrix elements
vanish. The conversions are efficient when the mass eigenstates are
well-separated in space but suppressed if their wave-packets overlap; the
suppression is most severe for mass-degenerate eigenstates in flat space-time.
The mass eigenstate conversions can lead to an interesting process, called
`quantum evaporation,' in which mixed particles, initially confined deep inside
a gravitational potential well and scattering only off each other, can escape
from it without extra energy supply leaving nothing behind inside the potential
at $t\to \infty$. Implications for the cosmic neutrino background and the
two-component dark matter model are discussed and a prediction for the direct
detection dark matter experiments is made.
