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The problem of the initial conditions in flavoured leptogenesis and the tauon N2-dominated scenario

The problem of the initial conditions in flavoured leptogenesis and the tauon N2-dominated scenario
The problem of the initial conditions in flavoured leptogenesis and the tauon N2-dominated scenario
We discuss the conditions to realise a scenario of ‘strong thermal leptogenesis,’ where the final asymmetry is fully independent of the initial conditions, taking into account both heavy and light neutrino flavour effects. In particular, the contribution to the final asymmetry from an initial pre-existing asymmetry has to be negligible.We show that in the case of a hierarchical right-handed (RH) neutrino mass spectrum, the only possible way is an N2-dominated leptogenesis scenario with a lightest RH neutrino mass M1 <<109 GeV and with a next-to-lightest RH neutrino mass 1012 GeV >> M2  >> 109 GeV. This scenario necessarily requires the presence of a heaviest third RH neutrino specie. Moreover, we show that the final asymmetry has to be dominantly produced in the tauon flavour while the electron and the muon asymmetries have to be efficiently washed-out by the lightest RH neutrino inverse processes. Intriguingly, such seemingly special conditions for successful strong thermal leptogenesis are naturally fulfilled within SO(10)-inspired models.
Besides the tauon N2-dominated scenario, successful strong thermal leptogenesis is also achieved in scenarios with quasi-degenerate RH neutrino masses. We also comment on the supersymmetric case. We also derive an expression for the final asymmetry produced from leptogenesis taking fully into account heavy neutrino flavour effects in the specific case M1 >> 1012 GeV (heavy flavoured scenario), a result that can be extended to any other mass pattern.
0550-3213
Bertuzzo, Enrico
d35bf853-fe74-40f7-8480-196664afd2d5
Di Bari, Pasquale
3fe21e59-0eff-41bc-8faa-fdd817146418
Marzola, Luca
53d3bd4b-b60a-46d9-a3dd-96d0bb305bff
Bertuzzo, Enrico
d35bf853-fe74-40f7-8480-196664afd2d5
Di Bari, Pasquale
3fe21e59-0eff-41bc-8faa-fdd817146418
Marzola, Luca
53d3bd4b-b60a-46d9-a3dd-96d0bb305bff

Bertuzzo, Enrico, Di Bari, Pasquale and Marzola, Luca (2011) The problem of the initial conditions in flavoured leptogenesis and the tauon N2-dominated scenario. Nuclear Physics B. (doi:10.1016/j.nuclphysb.2011.03.027).

Record type: Article

Abstract

We discuss the conditions to realise a scenario of ‘strong thermal leptogenesis,’ where the final asymmetry is fully independent of the initial conditions, taking into account both heavy and light neutrino flavour effects. In particular, the contribution to the final asymmetry from an initial pre-existing asymmetry has to be negligible.We show that in the case of a hierarchical right-handed (RH) neutrino mass spectrum, the only possible way is an N2-dominated leptogenesis scenario with a lightest RH neutrino mass M1 <<109 GeV and with a next-to-lightest RH neutrino mass 1012 GeV >> M2  >> 109 GeV. This scenario necessarily requires the presence of a heaviest third RH neutrino specie. Moreover, we show that the final asymmetry has to be dominantly produced in the tauon flavour while the electron and the muon asymmetries have to be efficiently washed-out by the lightest RH neutrino inverse processes. Intriguingly, such seemingly special conditions for successful strong thermal leptogenesis are naturally fulfilled within SO(10)-inspired models.
Besides the tauon N2-dominated scenario, successful strong thermal leptogenesis is also achieved in scenarios with quasi-degenerate RH neutrino masses. We also comment on the supersymmetric case. We also derive an expression for the final asymmetry produced from leptogenesis taking fully into account heavy neutrino flavour effects in the specific case M1 >> 1012 GeV (heavy flavoured scenario), a result that can be extended to any other mass pattern.

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Published date: 2 April 2011

Identifiers

Local EPrints ID: 181825
URI: http://eprints.soton.ac.uk/id/eprint/181825
ISSN: 0550-3213
PURE UUID: a397b29d-b60c-45bd-9ea6-9c4ee2c78bef

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Date deposited: 27 Apr 2011 08:49
Last modified: 14 Mar 2024 02:57

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Author: Enrico Bertuzzo
Author: Luca Marzola

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