Hidden dark matter sector, dark radiation, and the CMB

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; Okui, Takemichi

doi:10.1103/physrevd.92.055033

Cited by 89 publications

(103 citation statements)

References 126 publications

(159 reference statements)

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“…Very light states (m eV) increase the radiation density at recombination, leaving an imprint on the CMB. This effect is usually expressed as an equivalent number of additional neutrino species [121][122][123][124][125], with measurements limiting ∆N CM B ef f < 0.30 [2]. More massive states can avoid the CMB bound, but can modify the expansion rate during BBN, with the limit for masses below m MeV given by ∆N BBN ef f 0.5 [126].…”

Section: Probing New Degrees Of Freedommentioning

confidence: 99%

Probing the pre-BBN universe with gravitational waves from cosmic strings

Cui

Lewicki

Morrissey

et al. 2019

J. High Energ. Phys.

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167

216

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Many motivated extensions of the Standard Model predict the existence of cosmic strings. Gravitational waves originating from the dynamics of the resulting cosmic string network have the ability to probe many otherwise inaccessible properties of the early universe. In this study we show how the spectrum of gravitational waves from a cosmic string network can be used to test the equation of state of the early universe prior to Big Bang Nucleosynthesis (BBN). We also demonstrate that current and planned gravitational wave detectors such as LIGO, LISA, DECIGO/BBO, and ET/CE have the potential to detect signals of a non-standard pre-BBN equation of state and evolution of the early universe (e.g., early non-standard matter domination or kination domination) or new degrees of freedom active in the early universe beyond the sensitivity of terrestrial collider experiments and cosmic microwave background measurements. by reheating to a very hot radiation phase with temperature T TeV, which then cooled adiabatically until giving way to the recent matter and dark energy phases. We refer to this scenario, with only radiation domination (RD) over many orders of magnitude in temperature between reheating and the matter epoch, as the standard cosmology [11]. While this assumption is made frequently (and often implicitly), it has not been tested directly. Furthermore, non-standard cosmological scenarios with an extended period of domination by something other than radiation between inflation and BBN have strong motivation from many perspectives, including dark matter, axions, string compactification, reheating, and baryogenesis [10,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Testing the paradigm of pre-BBN cosmology is therefore of great significance in advancing our understanding of the universe.Gravitational waves (GWs) may provide a means of looking back in time beyond the BBN epoch and probing the universe in its very early stages [10,[27][28][29]. The observation of binary mergers by the LIGO/Virgo collaboration has already given further support to the ΛCDM cosmology [30], although -and this is important to the motivation of this work -the GWs observed were created only relatively recently. Opportunity to look even further back in time with GWs arises because, in contrast to photons, GWs freestream throughout the entire history of the cosmos. Indeed, GWs emitted as far back as inflation could potentially be detected by LIGO/Virgo [31] or proposed future detectors such as LISA [32], BBO/DECIGO [33], the Einstein Telescope (ET) [34, 35], and Cosmic Explorer (CE) [36].A stable and predictable source of primordial GWs is needed if they are to be used to test very early cosmology. Two promising and well-motivated potential sources are cosmic strings [37][38][39][40] and primordial inflation [41][42][43]. The application of inflationary GWs to probe the expansion history of the universe was studied in Refs. [44][45][46][47] and for non-standard histories in Refs. [48][49][50][51]. However, current limits from CM...

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Section: Probing New Degrees Of Freedommentioning

confidence: 99%

Probing the pre-BBN universe with gravitational waves from cosmic strings

Cui

Lewicki

Morrissey

et al. 2019

J. High Energ. Phys.

Self Cite

167

216

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“…In the very early time of our universe, shortly after the hot Big Bang, WIMP DM maintains in thermal equilibrium with the SM particles via rapid 2-to-2 annihilation (for variations such as annihilating into dark sector particles, see for instance, Refs. [7][8][9][10]. This annihilation rate is approximately Γ ann ∼ n eq χ σ ann v , where n eq χ is the number density of χ following the equilibrium distribution.…”

Section: Thermal History Of a Wimp-type Of Particlementioning

confidence: 96%

A review of WIMP baryogenesis mechanisms

Cui

2015

Mod. Phys. Lett. A

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It was recently proposed that weakly interacting massive particles (WIMP) may provide new ways of generating the observed baryon asymmetry in the early universe, as well as addressing the cosmic coincidence between dark matter (DM) and baryon abundances. This suggests a new possible connection between weak scale new particle physics and modern cosmology. This review summarizes the general ideas and simple model examples of the two recently proposed WIMP baryogenesis mechanisms: baryogenesis from WIMP DM annihilation during thermal freeze-out, and baryogenesis from metastable WIMP decay after thermal freeze-out. This review also discusses the interesting phenomenology of these models, in particular, the experimental signals that can be probed in the intensity frontier experiments and the large hadron collider (LHC) experiments.

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“…In calculating the relic abundance of χ, we follow the semi-analytic approach as detailed in Refs. [50] and [74],…”

Section: A Equilibrationmentioning

confidence: 99%

Thermal neutrino portal to sub-MeV dark matter

Berlin

Blinov

2019

Phys. Rev. D

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Thermal relics lighter than an MeV contribute to the energy density of the universe at the time of nucleosynthesis and recombination. Constraints on extra radiation degrees of freedom typically exclude even the simplest of such dark sectors. We explore the possibility that a sub-MeV dark sector entered equilibrium with the Standard Model after neutrino-photon decoupling, which significantly weakens these constraints and naturally arises in the context of neutrino mass generation through the spontaneous breaking of lepton number. Acquiring an adequate dark matter abundance independently motivates the MeV-scale in these models through the coincidence of gravitational, matter-radiation equality, and neutrino mass scales, (m Pl /T MRE ) 1/4 mν ∼ MeV. This class of scenarios will be decisively tested by future measurements of the cosmic microwave background and matter structure of the universe. While the dark sector dominantly interacts with Standard Model neutrinos, large couplings to nucleons are possible in principle, leading to observable signals at proposed low-threshold direct detection experiments. arXiv:1807.04282v1 [hep-ph]

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Hidden dark matter sector, dark radiation, and the CMB

Cited by 89 publications

References 126 publications

Probing the pre-BBN universe with gravitational waves from cosmic strings

Probing the pre-BBN universe with gravitational waves from cosmic strings

A review of WIMP baryogenesis mechanisms

Thermal neutrino portal to sub-MeV dark matter

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