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Successful N2 leptogenesis with flavour coupling effects in realistic unified models

Successful N2 leptogenesis with flavour coupling effects in realistic unified models
Successful N2 leptogenesis with flavour coupling effects in realistic unified models
In realistic unified models involving so-called SO(10)-inspired patterns of Dirac and heavy right-handed (RH) neutrino masses, the lightest right-handed neutrino N1 is too light to yield successful thermal leptogenesis, barring highly fine tuned solutions, while the second heaviest right-handed neutrino N2 is typically in the correct mass range. We show that flavour coupling effects in the Boltzmann equations may be crucial to the success of such N2 dominated leptogenesis, by helping to ensure that the flavour asymmetries produced at the N2 scale survive N1 washout. To illustrate these effects we focus on N2 dominated leptogenesis in an existing model, the A to Z of flavour with Pati-Salam, where the neutrino Dirac mass matrix may be equal to an up-type quark mass matrix and has a particular constrained structure. The numerical results, supported by analytical insight, show that in order to achieve successful N2 leptogenesis, consistent with neutrino phenomenology, requires a "flavour swap scenario" together with a less hierarchical pattern of RH neutrino masses than naively expected, at the expense of some mild fine-tuning. In the considered A to Z model neutrino masses are predicted to be normal ordered, with an atmospheric neutrino mixing angle well into the second octant and the Dirac phase δ ≅ 20º, a set of predictions that will be tested in the next years in neutrino oscillation experiments. Flavour coupling effects may be relevant for other SO(10)-inspired unified models where N2 leptogenesis is necessary.
1475-7516
1-23
Di Bari, Pasquale
3fe21e59-0eff-41bc-8faa-fdd817146418
King, Stephen F.
f8c616b7-0336-4046-a943-700af83a1538
Di Bari, Pasquale
3fe21e59-0eff-41bc-8faa-fdd817146418
King, Stephen F.
f8c616b7-0336-4046-a943-700af83a1538

Di Bari, Pasquale and King, Stephen F. (2015) Successful N2 leptogenesis with flavour coupling effects in realistic unified models. Journal of Cosmology and Astroparticle Physics, 2015 (10), 1-23, [8]. (doi:10.1088/1475-7516/2015/10/008).

Record type: Article

Abstract

In realistic unified models involving so-called SO(10)-inspired patterns of Dirac and heavy right-handed (RH) neutrino masses, the lightest right-handed neutrino N1 is too light to yield successful thermal leptogenesis, barring highly fine tuned solutions, while the second heaviest right-handed neutrino N2 is typically in the correct mass range. We show that flavour coupling effects in the Boltzmann equations may be crucial to the success of such N2 dominated leptogenesis, by helping to ensure that the flavour asymmetries produced at the N2 scale survive N1 washout. To illustrate these effects we focus on N2 dominated leptogenesis in an existing model, the A to Z of flavour with Pati-Salam, where the neutrino Dirac mass matrix may be equal to an up-type quark mass matrix and has a particular constrained structure. The numerical results, supported by analytical insight, show that in order to achieve successful N2 leptogenesis, consistent with neutrino phenomenology, requires a "flavour swap scenario" together with a less hierarchical pattern of RH neutrino masses than naively expected, at the expense of some mild fine-tuning. In the considered A to Z model neutrino masses are predicted to be normal ordered, with an atmospheric neutrino mixing angle well into the second octant and the Dirac phase δ ≅ 20º, a set of predictions that will be tested in the next years in neutrino oscillation experiments. Flavour coupling effects may be relevant for other SO(10)-inspired unified models where N2 leptogenesis is necessary.

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Accepted/In Press date: 24 August 2015
e-pub ahead of print date: 2 October 2015
Organisations: Theoretical Partical Physics Group

Identifiers

Local EPrints ID: 401041
URI: http://eprints.soton.ac.uk/id/eprint/401041
ISSN: 1475-7516
PURE UUID: cb4c8f4f-3573-40a3-a41f-41d54d4508ca

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Date deposited: 04 Oct 2016 08:10
Last modified: 02 Mar 2021 17:34

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