Dark matter relic abundance beyond kinetic equilibrium

Binder, Tobias; Bringmann, Torsten; Gustafsson, M.; Hryczuk, Andrzej

doi:10.1140/epjc/s10052-021-09357-5

Cited by 42 publications

(55 citation statements)

References 73 publications

(129 reference statements)

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“…Even those processes will eventually lose their competition against the Hubble rate and decouple. Note that kinetic decoupling can occur before chemical decoupling in which case one needs to solve the full Boltzmann equations for the phase space distributions [31,32]. This has an effect on the relic density and is often numerically challenging.…”

Section: Departure From Kinetic Equilibriummentioning

confidence: 99%

Analyzing the Hubble tension through hidden sector dynamics in the early universe

Aboubrahim,

Klasen,

Nath

2022

Preprint

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The recent analysis from the SH0ES Collaboration has confirmed the existence of a Hubble tension between measurements at high redshift (z > 1000) and at low redshift (z < 1) at the 5σ level with the low redshift measurement giving a higher value. In this work we propose a particle physics model that can resolve the Hubble tension via an out of equilibrium hidden sector coupled to the visible sector. The particles that populate the dark sector consist of a dark fermion, which acts as dark matter, a dark photon, a massive scalar and a massless pseudo-scalar. Assuming no initial population of particles in the dark sector, feeble couplings between the visible and the hidden sectors via kinetic mixing populate the dark sector even though the number densities of hidden sector particles never reach their equilibrium distribution and the two sectors remain at different temperatures. A cosmologically consistent analysis is presented where a correlated evolution of the visible and the hidden sectors with coupled Boltzmann equations involving two temperatures, one for the visible sector and the other for the hidden sector, is carried out. The relic density of the dark matter constituted of dark fermions is computed in this two-temperature formalism. As a consequence, BBN predictions are upheld with a minimal contribution to ∆N eff . However, the out-of-equilibrium decay of the massive scalar to the massless pseudoscalar close to the recombination time causes an increase in ∆N eff to resolve the Hubble tension.

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Section: Departure From Kinetic Equilibriummentioning

confidence: 99%

Analyzing the Hubble tension through hidden sector dynamics in the early universe

Aboubrahim,

Klasen,

Nath

2022

Preprint

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“…To showcase the application of DRAKE here we briefly present two selected examples. More extended discussion and details can be found in [6].…”

Section: Example Physics Scenariosmentioning

confidence: 99%

“…Here we report on introducing a new public code, DRAKE [6] (Dark matter Relic Abundance beyond Kinetic Equilibrium) , which for the case of annihilating DM implements: i) coupled equations for the number density and higher moments of the DM phase space distribution and ii) the full Boltzmann equation directly at the phase space level. Therefore, DRAKE provides a tool to predict the relic density also in situations where the underlying assumptions of the traditional approach cannot be justified.…”

Section: Introductionmentioning

confidence: 99%

DRAKE: Dark matter Relic Abundance beyond Kinetic Equilibrium

Hryczuk¹

2022

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2021)

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In the usual approach to the dark matter thermal relic abundance calculation an assumption of local thermal equilibrium is made. This proceedings presents a numerical precision tool DRAKE (drake.hepforge.org) that goes beyond this assumption by tracing not only the DM relic density, but also its velocity dispersion and full phase space distribution function. We review the general motivation for this approach and, for illustration, highlight two concrete classes of models where kinetic and chemical decoupling are intertwined in a way that can impact the value of the relic density by as much as an order of magnitude: dark matter annihilation via a narrow resonance and 'forbidden' annihilation to final states that are kinematically inaccessible at threshold.

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“…Resonances with the Higgs boson h or with the scalar ρ, which occur for 2m θ m h or 2m θ m ρ (see figure 1 (a)). In this region, kinetic equilibrium of the final states at freeze-out may not be a good assumption, and therefore there is some uncertainty in the parameter values for which the abundance is reproduced [48][49][50]. 2.…”

Section: Dark Matter Relic Abundancementioning

confidence: 99%

“…In ref. [49] the case in which kinetic equilibrium of the final states at freeze-out may not be a good assumption has also been studied. 4.…”

Section: Dark Matter Relic Abundancementioning

confidence: 99%

Dark matter from a complex scalar singlet: the role of dark CP and other discrete symmetries

Coito

Faubel

Herrero-García

et al. 2021

J. High Energ. Phys.

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We study the case of a pseudo-scalar dark matter candidate which emerges from a complex scalar singlet, charged under a global U(1) symmetry, which is broken both explicitly and spontaneously. The pseudo-scalar is naturally stabilized by the presence of a remnant discrete symmetry: dark CP. We study and compare the phenomenology of several simplified models with only one explicit symmetry breaking term. We find that several regions of the parameter space are able to reproduce the observed dark matter abundance while respecting direct detection and invisible Higgs decay limits: in the resonances of the two scalars, featuring the known as forbidden or secluded dark matter, and through non-resonant Higgs-mediated annihilations. In some cases, combining different measurements would allow one to distinguish the breaking pattern of the symmetry. Moreover, this setup admits a light DM candidate at the sub-GeV scale. We also discuss the situation where more than one symmetry breaking term is present. In that case, the dark CP symmetry may be spontaneously broken, thus spoiling the stability of the dark matter candidate. Requiring that this does not happen imposes a constraint on the allowed parameter space. Finally, we consider an effective field theory approach valid in the pseudo-Nambu-Goldstone boson limit and when the U(1) breaking scale is much larger than the electroweak scale.

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Dark matter relic abundance beyond kinetic equilibrium

Cited by 42 publications

References 73 publications

Analyzing the Hubble tension through hidden sector dynamics in the early universe

Analyzing the Hubble tension through hidden sector dynamics in the early universe

DRAKE: Dark matter Relic Abundance beyond Kinetic Equilibrium

Dark matter from a complex scalar singlet: the role of dark CP and other discrete symmetries

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