Seminarium "High Energy, Cosmology and Astro-particle Physics (HECA)"
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2022-04-26 (14:00) 
Jan Heisig (Louvain University, CP3 and RWTH Aachen)
Bound state effects on dark matter coannihilation - pushing the boundaries of minimal dark sectors
Note unusual time!!!
Bound-state formation effects can have a large impact on the dynamics of dark matter freeze-out in the early Universe, in particular, for colored coannihilators. We present a general formalism to include an arbitrary number of excitations of bound states in terms of an effective annihilation cross section. For a coannihilator in the fundamental representation of SU(3)c, we discuss radiative bound-state formation, decay, and electromagnetic transition rates among them. We then assess the impact of bound states within a minimal dark sector containing a Majorana dark matter candidate and a colored scalar t-channel mediator. We consider the well-known coannihilation regime as well as the regime of conversion-driven freeze-out (or coscattering), where the relic abundance is set by the freeze-out of conversion processes. We find that the latter is considerably enhanced into the multi-TeV region due to bound-state effects. This has far-reaching implications for the search strategies at the upcoming LHC runs as conversion-driven freeze-out predicts a long-lived coannihilator. We also comment on the role of bound-state effects in scenarios of non-thermalized dark matter, i.e. freeze-in or superWIMP production.
https://us02web.zoom.us/j/85478248551
Bound-state formation effects can have a large impact on the dynamics of dark matter freeze-out in the early Universe, in particular, for colored coannihilators. We present a general formalism to include an arbitrary number of excitations of bound states in terms of an effective annihilation cross section. For a coannihilator in the fundamental representation of SU(3)c, we discuss radiative bound-state formation, decay, and electromagnetic transition rates among them. We then assess the impact of bound states within a minimal dark sector containing a Majorana dark matter candidate and a colored scalar t-channel mediator. We consider the well-known coannihilation regime as well as the regime of conversion-driven freeze-out (or coscattering), where the relic abundance is set by the freeze-out of conversion processes. We find that the latter is considerably enhanced into the multi-TeV region due to bound-state effects. This has far-reaching implications for the search strategies at the upcoming LHC runs as conversion-driven freeze-out predicts a long-lived coannihilator. We also comment on the role of bound-state effects in scenarios of non-thermalized dark matter, i.e. freeze-in or superWIMP production.
https://us02web.zoom.us/j/85478248551