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Density matrix calculation of the dark matter abundance in the Higgs induced right-handed neutrino mixing model

Density matrix calculation of the dark matter abundance in the Higgs induced right-handed neutrino mixing model
Density matrix calculation of the dark matter abundance in the Higgs induced right-handed neutrino mixing model
We present new results on the calculation of the dark matter relic abundance within the Higgs induced right-handed neutrino mixing model, solving the associated density matrix equation. For a benchmark value of the dark matter mass MDM = 220 TeV, we show the evolution of the abundance and how this depends on reheat temperature, dark matter lifetime and source right-handed neutrino mass MS, with the assumption MS < MDM. We compare the results with those obtained within the Landau-Zener approximation, showing that the latter largely overestimates the final abundance giving some analytical insight. However, we also notice that since in the density matrix formalism the production is non-resonant, this allows source right-handed neutrino masses below the W boson mass, making dark matter more stable at large mass values. This opens an allowed region for initial vanishing source right-handed neutrino abundance. For example, for MS ≳ 1 GeV, we find MDM≳ 20 PeV. Otherwise, for MS > MW∼ 100 GeV, one has to assume a thermalisation of the source right-handed neutrinos prior to the freeze-in of the dark matter abundance. This results into a large allowed range for MDM, depending on MS. For example, imposing MS ≳ 300 GeV, allowing also successful leptogenesis, we find 00.5 ≲ MDM/TeV ≲ 50. We also discuss in detail leptogenesis with two quasi-degenerate right-handed neutrinos, showing a case when observed dark matter abundance and matter-antimatter asymmetry are simultaneously reproduced. Finally, we comment on how an initial thermal source right-handed neutrino abundance can be justified and on how our results suggest that also the interesting case where MDM < MS, embeddable in usual high scale two right-handed neutrino seesaw models, might be viable.
1475-7516
Di Bari, Pasquale
3fe21e59-0eff-41bc-8faa-fdd817146418
Farrag, Kareem Ramadan Hassan Aly Muhammad
0d181def-4c75-40d8-b872-3d0a51ca8892
Samanta, Rome
8016c2a4-1a27-448c-86bc-d2e4aff88737
Zhou, Y.
a5398d19-1c29-40ca-9c74-72a1fa2db5e6
Di Bari, Pasquale
3fe21e59-0eff-41bc-8faa-fdd817146418
Farrag, Kareem Ramadan Hassan Aly Muhammad
0d181def-4c75-40d8-b872-3d0a51ca8892
Samanta, Rome
8016c2a4-1a27-448c-86bc-d2e4aff88737
Zhou, Y.
a5398d19-1c29-40ca-9c74-72a1fa2db5e6

Di Bari, Pasquale, Farrag, Kareem Ramadan Hassan Aly Muhammad, Samanta, Rome and Zhou, Y. (2020) Density matrix calculation of the dark matter abundance in the Higgs induced right-handed neutrino mixing model. Journal of Cosmology and Astroparticle Physics, (10). (doi:10.1088/1475-7516/2020/10/029).

Record type: Article

Abstract

We present new results on the calculation of the dark matter relic abundance within the Higgs induced right-handed neutrino mixing model, solving the associated density matrix equation. For a benchmark value of the dark matter mass MDM = 220 TeV, we show the evolution of the abundance and how this depends on reheat temperature, dark matter lifetime and source right-handed neutrino mass MS, with the assumption MS < MDM. We compare the results with those obtained within the Landau-Zener approximation, showing that the latter largely overestimates the final abundance giving some analytical insight. However, we also notice that since in the density matrix formalism the production is non-resonant, this allows source right-handed neutrino masses below the W boson mass, making dark matter more stable at large mass values. This opens an allowed region for initial vanishing source right-handed neutrino abundance. For example, for MS ≳ 1 GeV, we find MDM≳ 20 PeV. Otherwise, for MS > MW∼ 100 GeV, one has to assume a thermalisation of the source right-handed neutrinos prior to the freeze-in of the dark matter abundance. This results into a large allowed range for MDM, depending on MS. For example, imposing MS ≳ 300 GeV, allowing also successful leptogenesis, we find 00.5 ≲ MDM/TeV ≲ 50. We also discuss in detail leptogenesis with two quasi-degenerate right-handed neutrinos, showing a case when observed dark matter abundance and matter-antimatter asymmetry are simultaneously reproduced. Finally, we comment on how an initial thermal source right-handed neutrino abundance can be justified and on how our results suggest that also the interesting case where MDM < MS, embeddable in usual high scale two right-handed neutrino seesaw models, might be viable.

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Density matrix calculation of the dark matter abundance in the Higgs induced right-handed neutrino mixing model - Accepted Manuscript
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Accepted/In Press date: 23 August 2020
e-pub ahead of print date: 9 October 2020

Identifiers

Local EPrints ID: 445303
URI: http://eprints.soton.ac.uk/id/eprint/445303
ISSN: 1475-7516
PURE UUID: cced5655-b7e1-4569-9c77-0960a60bafc2

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Date deposited: 02 Dec 2020 17:31
Last modified: 10 Jan 2022 05:50

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Contributors

Author: Rome Samanta
Author: Y. Zhou

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