Speaker
Description
Recently, a question about how far chemical freeze-out of heavy Dark
Matter (DM) particles can be pushed down in temperature has been
raised. In this case, kinetic equilibration of heavy DM through
elastic collisions with strongly interacting Standard Model particles
such as quarks and gluons at the temperature of a few GeV could
potentially complicate the consideration. Thus, we study kinetic
equilibration of heavy dark matter particles in non-perturbative
regime using Langevin equation simulation. We note that the kinetic
equilibration of slowly moving DM particle in the thermal bath of SM
particles is analogous to kinetic equilibration of heavy quarks in
Quark-Gluon Plasma and that Langevin equation method is superior
to a standard formulation based on Boltzmann equation because Langevin
simulation allows systematic study even in non-perturbative
regime. As a concrete numerical example, we consider a scalar singlet
DM particle interacting with quarks and gluons and find that the
momentum distribution of DM particle retains the Gaussian form
although the spectrum becomes red-tilted and its overall effect on the
chemical equilibration of DM particles to be {\cal O} (20) %.
