The role of unitarisation on dark-matter freeze-out via metastable bound states
arXiv:2505.20443 · doi:10.1088/1475-7516/2025/09/026
Abstract
In many Abelian and non-Abelian theories, standard calculations of radiative bound-state formation violate partial-wave unitarity - even at arbitrarily small couplings - when capture into excited states is considered. Recent work demonstrated that unitarity can be restored by the proper resummation of squared inelastic processes in the self-energy of the incoming state. We examine how unitarisation affects dark-matter thermal decoupling, given that the formation and decay of metastable dark-matter bound states are critical in determining the relic abundance, especially for multi-TeV dark matter. We consider an Abelian model featuring bound-state formation via emission of a light scalar that carries a conserved charge, whose dynamics also emulates relevant aspects of non-Abelian theories. Incorporating capture into excited states, we show that, without proper treatment, unitarity violation is so severe as to prevent freeze-out. Resumming the squared bound-state formation processes restores unitarity and ensures freeze-out, while capture into excited levels still significantly depletes dark matter. We further discuss the impact of higher partial waves, both within and beyond the present model. Finally, we point out the intriguing possibility of late dark-matter decoupling that can affect structure formation.
arXiv comment39 pages, 14 figures
References in corpus (31)
- Sommerfeld factor for arbitrary partial wave processes
- Bound-state formation for thermal relic dark matter and unitarity
- The one-dimensional power spectrum from the SDSS DR14 Ly forests
- Revealing reionization with the thermal history of the intergalactic medium: new constraints from the Lyman- flux power spectrum
- Dark-matter bound states from Feynman diagrams
- New Constraints on Warm Dark Matter from the Lyman- Forest Power Spectrum
- Gluino Coannihilation Revisited
- Self-consistent Calculation of the Sommerfeld Enhancement
- Radiative bound-state-formation cross-sections for dark matter interacting via a Yukawa potential
- Thermal decoupling and the smallest subhalo mass in dark matter models with Sommerfeld-enhanced annihilation rates
- Asymmetric thermal-relic dark matter: Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds
- Radiative bound-state formation in unbroken perturbative non-Abelian theories and implications for dark matter
- Rapid thermal co-annihilation through bound states in QCD
- Dark Matter Sommerfeld-enhanced annihilation and Bound-state decay at finite temperature
- Re-derived overclosure bound for the inert doublet model
- Bound-state effects on dark matter coannihilation: Pushing the boundaries of conversion-driven freeze-out
- Dark Matter bound-state formation at higher order: a non-equilibrium quantum field theory approach
- Higgs-mediated bound states in dark-matter models
- Scalar dark matter coannihilating with a coloured fermion
- Rapid bound-state formation of Dark Matter in the Early Universe
- Dark Matter Bound State Formation in Fermionic DM model with Light Dark Photon and Dark Higgs Boson
- Dark matter bound states via emission of scalar mediators
- Dark matter bound state formation via emission of a charged scalar
- Excited bound states and their role in dark matter production
- Saha equilibrium for metastable bound states and dark matter freeze-out
- Bound states of WIMP dark matter in Higgs-portal models. Part I. Cross-sections and transition rates
- Impact of bound states on non-thermal dark matter production
- Bound states of WIMP dark matter in Higgs-portal models. Part II. Thermal decoupling
- Unitarity in the non-relativistic regime and implications for dark matter
- Radiation back-reaction during dark-matter freeze-out via metastable bound states
- Critical and super-critical scatterings in baryogenesis and leptogenesis