Thermal neutrino portal to sub-MeV dark matter

Berlin, Asher; Blinov, Nikita

doi:10.1103/physrevd.99.095030

Cited by 64 publications

(62 citation statements)

References 154 publications

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“…In this context, let us comment on possible mechanisms to realize ν-quilibration. One possibility is to introduce a small Yukawa-like coupling between S and the light neutrinos [31,32], for instance via a right-handed neutrino, N , with an interaction term of the form λSN N . The assumption of a type-I seesaw then yields a suppressed coupling of the desired form λmν m N Sνν, where ν is a light neutrino field after electroweak symmetry breaking, and m ν and m N are the masses of the light and heavy neutrinos, respectively.…”

Section: A Singlet Scalarsmentioning

confidence: 99%

“…Hidden sector equilibrates with neutrinos (ν-quilibration). While the hidden sector cannot be in thermal contact with the photon bath at temperatures around or below the BBN temperature T BBN , there is the possibility that it (re-)couples with neutrinos after the latter have lost thermal contact with the photons [31,32]. This scenario, which we will dub "ν-quilibration", corresponds to the following sequence of events:…”

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confidence: 99%

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Dark, cold, and noisy: constraining secluded hidden sectors with gravitational waves

Breitbach

Kopp

Madge

et al. 2019

J. Cosmol. Astropart. Phys.

188

191

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We explore gravitational wave signals arising from first-order phase transitions occurring in a secluded hidden sector, allowing for the possibility that the hidden sector may have a different temperature than the Standard Model sector. We present the sensitivity to such scenarios for both current and future gravitational wave detectors in a model-independent fashion. Since secluded hidden sectors are of particular interest for dark matter models at the MeV scale or below, we pay special attention to the reach of pulsar timing arrays. Cosmological constraints on light degrees of freedom restrict the number of sub-MeV particles in a hidden sector, as well as the hidden sector temperature. Nevertheless, we find that observable first-order phase transitions can occur. To illustrate our results, we consider two minimal benchmark models: a model with two gauge singlet scalars and a model with a spontaneously broken U (1) gauge symmetry in the hidden sector. CONTENTS

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Section: A Singlet Scalarsmentioning

confidence: 99%

mentioning

confidence: 99%

Dark, cold, and noisy: constraining secluded hidden sectors with gravitational waves

Breitbach

Kopp

Madge

et al. 2019

J. Cosmol. Astropart. Phys.

188

191

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“…Such a discrepancy could be ameliorated if the expansion rate of the universe departed from the predictions of standard ΛCDM cosmology at early times [9,10]. Particularly well motivated within this context are scenarios in which the energy density in relativistic particles exceeds that predicted by the SM, generally parameterized in terms of a non-zero contribution to the effective number of neutrino species, ∆N eff [11][12][13][14][15]. Scenarios involving early dark energy [16][17][18] or a component of decaying dark matter [19] have also been proposed to address this tension.…”

Section: Introductionmentioning

confidence: 99%

Cosmology with a very light Lμ − Lτ gauge boson

Escudero

Hooper

Krnjaic

et al. 2019

J. High Energ. Phys.

242

273

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In this paper, we explore in detail the cosmological implications of an abelian L µ − L τ gauge extension of the Standard Model featuring a light and weakly coupled Z . Such a scenario is motivated by the longstanding ∼ 4σ discrepancy between the measured and predicted values of the muon's anomalous magnetic moment, (g − 2) µ , as well as the tension between late and early time determinations of the Hubble constant. If sufficiently light, the Z population will decay to neutrinos, increasing the overall energy density of radiation and altering the expansion history of the early universe. We identify two distinct regions of parameter space in this model in which the Hubble tension can be significantly relaxed. The first of these is the previously identified region in which a ∼ 10 − 20 MeV Z reaches equilibrium in the early universe and then decays, heating the neutrino population and delaying the process of neutrino decoupling. For a coupling of g µ−τ (3 − 8) × 10 −4 , such a particle can also explain the observed (g − 2) µ anomaly. In the second region, the Z is very light (m Z ∼ 1 eV to MeV) and very weakly coupled (g µ−τ ∼ 10 −13 to 10 −9 ). In this case, the Z population is produced through freeze-in, and decays to neutrinos after neutrino decoupling. Across large regions of parameter space, we predict a contribution to the energy density of radiation that can appreciably relax the reported Hubble tension, ∆N eff 0.2.

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“…The constraints are especially severe in the case of light DM. Thermal relic DM with a mass below an MeV is essentially ruled out [3][4][5][6][7][8][9], although a few exceptions do exist [8,[10][11][12]. These constraints are almost completely relaxed for DM that is a diluted hot relic.…”

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confidence: 99%

Light Dark Matter from Entropy Dilution

Evans

Ghalsasi

Gori

et al. 2020

J. High Energ. Phys.

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We show that a thermal relic which decouples from the standard model (SM) plasma while relativistic can be a viable dark matter (DM) candidate, if the decoupling is followed by a period of entropy dilution that heats up the SM, but not the dark sector. Such diluted hot relics can be as light as a keV, while accounting for the entirety of the DM, and not conflicting with cosmological and astrophysical measurements. The requisite dilution can be achieved via decays of a heavy state that dominates the energy budget of the universe in the early matter dominated era. The heavy state decays into the SM particles, heats up the SM plasma, and dilutes the hidden sector. The interaction required to equilibrate the two sectors in the early universe places a bound on the maximum possible dilution as a function of the decoupling temperature. As an example of diluted hot relic DM we consider a light Dirac fermion with a heavy dark photon mediator. We present constraints on the model from terrestrial experiments (current and future), astrophysics, and cosmology.ArXiv ePrint: nnnn.nnnnn

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Thermal neutrino portal to sub-MeV dark matter

Cited by 64 publications

References 154 publications

Dark, cold, and noisy: constraining secluded hidden sectors with gravitational waves

Dark, cold, and noisy: constraining secluded hidden sectors with gravitational waves

Cosmology with a very light Lμ − Lτ gauge boson

Light Dark Matter from Entropy Dilution

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