On thermal corrections to near-threshold annihilation

• Published in: Journal of cosmology and astroparticle physics 2017-01, Vol.2017 (1), p.13-13
• Main Authors: Kim, Seyong, Laine, M.
• Format: Article
• Language: English
• Subjects: ANNIHILATION; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOSON-EXCHANGE MODELS; BOSONS; BOUND STATE; CORRECTIONS; GLUINOS; MASS; MIXING ANGLE; NONLUMINOUS MATTER; PLASMA; RELATIVISTIC RANGE; SCATTERING; SPECTRA; SPIN; STRONG INTERACTIONS; TEV RANGE; UNIVERSE; VISIBLE RADIATION
• ISSN: 1475-7516; 1475-7516
• DOI: 10.1088/1475-7516/2017/01/013

We consider non-relativistic ''dark'' particles interacting through gauge boson exchange. At finite temperature, gauge exchange is modified in many ways: virtual corrections lead to Debye screening; real corrections amount to frequent scatterings of the heavy particles on light plasma constituents; mixing angles change. In a certain temperature and energy range, these effects are of order unity. Taking them into account in a resummed form, we estimate the near-threshold spectrum of kinetically equilibrated annihilating TeV scale particles. Weakly bound states are shown to 'melt' below freeze-out, whereas with attractive strong interactions, relevant e.g. for gluinos, bound states boost the annihilation rate by a factor 4 ... 80 with respect to the Sommerfeld estimate, thereby perhaps helping to avoid overclosure of the universe. Modestly non-degenerate dark sector masses and a way to combine the contributions of channels with different gauge and spin structures are also discussed.