  We study a system containing many particles of identical kinematics with a
zero range interaction that scatters one from the other, and with the possible
exchange of an attribute. Taking an initial condition in which the attribute is
asymmetrically distributed in the regions of momentum space occupied by the
particles, we study the rate at which it becomes uniformly distributed, through
collisions. We find, in some circumstances, a rate that is much faster than
that which would be estimated from cross-sections. This behavior is
attributable in some general sense to N-particle entanglement. We suggest
applications to neutrino physics, where the attribute is neutrino flavor.
