Speaker
Prof.
Seyong Kim
(Sejong University)
Description
The thermal Sommerfeld factor, concerning the co-annihilation rate
of heavy quarks in thermal equilibrium, is shown that it can be
defined in terms of two-point correlator ratios. Then, we calculate
non-perturbatively the co-annihilation rate of heavy quarks close to
thermal equilibrium using lattice NRQCD framework. Lattice
measurements indicate a modest suppression in the octet channel, in
reasonable agreement with perturbation theory, and a large enhancement
in the singlet channel, much above the perturbative prediction. The
additional enhancement is suggested to originate from bound state
formation and subsequent decay, omitted in previous estimates of
thermal Sommerfeld factors, which were meant for use in Boltzmann
equations governing single-particle phase space distributions. We show
how bound state effects can be included in perturbative
computations. The latter formalism may find applications also in
specific dark matter models.
Primary author
Prof.
Seyong Kim
(Sejong University)
Co-author
Prof.
Mikko Laine
(University of Bern)
