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Title: Successful N{sub 2} leptogenesis with flavour coupling effects in realistic unified models

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 N{sub 1} is too light to yield successful thermal leptogenesis, barring highly fine tuned solutions, while the second heaviest right-handed neutrino N{sub 2} 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 N{sub 2} dominated leptogenesis, by helping to ensure that the flavour asymmetries produced at the N{sub 2} scale survive N{sub 1} washout. To illustrate these effects we focus on N{sub 2} 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 N{sub 2} 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 mixingmore » angle well into the second octant and the Dirac phase δ≅ 20{sup o}, 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 N{sub 2} leptogenesis is necessary.« less

Authors:
;  [1]
  1. Department of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom)
Publication Date:
OSTI Identifier:
22525296
Resource Type:
Journal Article
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2015; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; BOLTZMANN EQUATION; COUPLING; FLAVOR MODEL; NEUTRINO MIXING ANGLE; NEUTRINO OSCILLATION; NEUTRINOS; PARTICLE PRODUCTION; QUARKS; REST MASS; SO-10 GROUPS; UNIFIED MODEL; VISIBLE RADIATION

Citation Formats

Bari, Pasquale Di, and King, Stephen F., E-mail: P.Di-Bari@soton.ac.uk, E-mail: king@soton.ac.uk. Successful N{sub 2} leptogenesis with flavour coupling effects in realistic unified models. United States: N. p., 2015. Web. doi:10.1088/1475-7516/2015/10/008.
Bari, Pasquale Di, & King, Stephen F., E-mail: P.Di-Bari@soton.ac.uk, E-mail: king@soton.ac.uk. Successful N{sub 2} leptogenesis with flavour coupling effects in realistic unified models. United States. doi:10.1088/1475-7516/2015/10/008.
Bari, Pasquale Di, and King, Stephen F., E-mail: P.Di-Bari@soton.ac.uk, E-mail: king@soton.ac.uk. Thu . "Successful N{sub 2} leptogenesis with flavour coupling effects in realistic unified models". United States. doi:10.1088/1475-7516/2015/10/008.
@article{osti_22525296,
title = {Successful N{sub 2} leptogenesis with flavour coupling effects in realistic unified models},
author = {Bari, Pasquale Di and King, Stephen F., E-mail: P.Di-Bari@soton.ac.uk, E-mail: king@soton.ac.uk},
abstractNote = {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 N{sub 1} is too light to yield successful thermal leptogenesis, barring highly fine tuned solutions, while the second heaviest right-handed neutrino N{sub 2} 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 N{sub 2} dominated leptogenesis, by helping to ensure that the flavour asymmetries produced at the N{sub 2} scale survive N{sub 1} washout. To illustrate these effects we focus on N{sub 2} 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 N{sub 2} 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≅ 20{sup o}, 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 N{sub 2} leptogenesis is necessary.},
doi = {10.1088/1475-7516/2015/10/008},
journal = {Journal of Cosmology and Astroparticle Physics},
issn = {1475-7516},
number = 10,
volume = 2015,
place = {United States},
year = {2015},
month = {10}
}