On thermal corrections to near-threshold annihilation

Abstract

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.

37 pages. v2: many clarifications and references added

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Cited by in corpus (9)

• Effects of QCD bound states on dark matter relic abundance
• Re-derived overclosure bound for the inert doublet model
• Freeze-in produced dark matter in the ultra-relativistic regime
• Higgs-mediated bound states in dark-matter models
• A QCD Debye mass in a broad temperature range
• Strong electroweak phase transition in $t$-channel simplified dark matter models
• Non-relativistic and potential non-relativistic effective field theories for scalar mediators
• Stop Co-Annihilation in the Minimal Supersymmetric Standard Model Revisited
• Bound-state formation, dissociation and decays of darkonium with potential non-relativistic Yukawa theory for scalar and pseudoscalar mediators