Leak-in dark matter

Evans, J.A.; Gaidau, Cristian; Shelton, Jessie

doi:10.1007/jhep01(2020)032

Cited by 22 publications

(33 citation statements)

References 114 publications

(205 reference statements)

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“…From a theoretical perspective, MeV-scale thermal dark matter candidates were shown to be viable some years ago [18][19][20] and, since then, a large number of MeV-scale dark matter models have appeared in the literature, see e.g. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Experimentally, with the aim of testing as many scenarios as possible [39], a complementary program has been developed to test the possible existence of MeV-scale dark matter particles and potential companions Beyond the Standard Model (BSM) [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB

Sabti

Alvey

Escudero

et al. 2020

J. Cosmol. Astropart. Phys.

181

174

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New light states thermally coupled to the Standard Model plasma alter the expansion history of the Universe and impact the synthesis of the primordial light elements. In this work, we carry out an exhaustive and precise analysis of the implications of MeV-scale BSM particles in Big Bang Nucleosynthesis (BBN) and for Cosmic Microwave Background (CMB) observations. We find that BBN observations set a lower bound on the thermal dark matter mass of mχ > 0.4 MeV at 2σ. This bound is independent of the spin and number of internal degrees of freedom of the particle, of the annihilation being s-wave or p-wave, and of the annihilation final state. Furthermore, we show that current BBN plus CMB observations constrain purely electrophilic and neutrinophilic BSM species to have a mass, mχ > 3.7 MeV at 2σ. We explore the reach of future BBN measurements and show that upcoming CMB missions should improve the bounds on light BSM thermal states to mχ > (10 − 15) MeV. Finally, we demonstrate that very light BSM species thermally coupled to the SM plasma are highly disfavoured by current cosmological observations. S nashwan.sabti@kcl.ac.uk

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Section: Introductionmentioning

confidence: 99%

Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB

Sabti

Alvey

Escudero

et al. 2020

J. Cosmol. Astropart. Phys.

181

174

View full text Add to dashboard Cite

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“…The curve labeled "Freeze-In" represents the parameter space for which the dominant, slower 1 − f fraction of the χ population can be produced out of equilibrium through the kinetic mixing interaction [15,83,86]. The effective DM millicharges κg D which match the observed rate for f < 1 are larger than the millicharges required to generate the observed relic abundance from freeze-in, so for those parameters, some interaction within the dark sector would be required to deplete the DM relic abundance [87,88].…”

Section: B Scenario 2: Direct Plasmon Excitation Through a Light Medmentioning

confidence: 99%

Dark matter interpretation of excesses in multiple direct detection experiments

et al. 2020

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We present a novel unifying interpretation of excess event rates observed in several dark matter directdetection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of ∼10 Hz=kg. However, none of these persistent excesses has yet been reported as a dark matter signal because individually, each can be attributed to different well-motivated but unmodeled backgrounds, and taken together, they cannot be explained by dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process, consistent with exciting a plasmon. We further show that plasmon excitation could arise in two compelling dark matter scenarios, both of which can explain rates of existing signal excesses in germanium and, at least at the order of magnitude level, across several single-electron threshold detectors. At least one of these scenarios also yields the correct relic density from thermal freeze-out. Both dark matter scenarios motivate a radical rethinking of the standard interpretations of dark matter-electron scattering from recent experiments.

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“…In light of these developments, it is well motivated to consider models in which the dark matter does not couple directly to the particle content of the Standard Model (SM), but instead annihilates to produce other particles which then decay through small couplings to the SM. Such hidden sector models have been studied extensively in the literature, increasing in interest in recent years [21][22][23][24][25][26][27][28][29][29][30][31][32][33][34][35][36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

A systematic study of hidden sector dark matter: application to the gamma-ray and antiproton excesses

Leane

Tsai

Wegsman

et al. 2020

J. High Energ. Phys.

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In hidden sector models, dark matter does not directly couple to the particle content of the Standard Model, strongly suppressing rates at direct detection experiments, while still allowing for large signals from annihilation. In this paper, we conduct an extensive study of hidden sector dark matter, covering a wide range of dark matter spins, mediator spins, interaction diagrams, and annihilation final states, in each case determining whether the annihilations are s-wave (thus enabling efficient annihilation in the universe today). We then go on to consider a variety of portal interactions that allow the hidden sector annihilation products to decay into the Standard Model. We broadly classify constraints from relic density requirements and dwarf spheroidal galaxy observations. In the scenario that the hidden sector was in equilibrium with the Standard Model in the early universe, we place a lower bound on the portal coupling, as well as on the dark matter's elastic scattering cross section with nuclei. We apply our hidden sector results to the observed Galactic Center gamma-ray excess and the cosmic-ray antiproton excess. We find that both of these excesses can be simultaneously explained by a variety of hidden sector models, without any tension with constraints from observations of dwarf spheroidal galaxies.

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Leak-in dark matter

Cited by 22 publications

References 114 publications

Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB

Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB

Dark matter interpretation of excesses in multiple direct detection experiments

A systematic study of hidden sector dark matter: application to the gamma-ray and antiproton excesses

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