Bound states of WIMP dark matter in Higgs-portal models. Part I. Cross-sections and transition rates

Abstract

We investigate the role of the Higgs \emph{doublet} in the thermal decoupling of multi-TeV dark matter coupled to the Weak interactions of the Standard Model and the Higgs. The Higgs doublet can mediate a long-range force that affects the annihilation processes and binds dark matter into bound states. More importantly, the emission of a Higgs doublet by a pair of dark matter particles can give rise to extremely rapid monopole bound-state formation processes and bound-to-bound transitions. We compute these effects in the unbroken electroweak phase. To this end, we consider the simplest renormalisable fermionic model, consisting of a singlet and a doublet under $S{U}_L(2)$ that are stabilised by a ${\mathbb{Z}}_2$ symmetry, in the regime where the two multiplets coannihilate. In a companion paper, we use the results to show that the formation of metastable bound states via Higgs-doublet emission and their decay decrease the relic density very significantly.

v1: 65 pages, 16 figures, 10 tables; v2: minor changes, published version

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Cited by in corpus (7)

• Impact of Sommerfeld Effect and Bound State Formation in Simplified $t$-Channel Dark Matter Models
• Bound-state formation, dissociation and decays of darkonium with potential non-relativistic Yukawa theory for scalar and pseudoscalar mediators
• Anatomy of singlet-doublet dark matter relic: annihilation, co-annihilation, co-scattering, and freeze-in
• Bound states of WIMP dark matter in Higgs-portal models. Part II. Thermal decoupling
• The role of unitarisation on dark-matter freeze-out via metastable bound states
• Radiation back-reaction during dark-matter freeze-out via metastable bound states
• Unitarity violation and restoration in radiative bound-state formation