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Title: Leptogenesis with heavy neutrino flavours: from density matrix to Boltzmann equations

Abstract

Leptogenesis with heavy neutrino flavours is discussed within a density matrix formalism. We write the density matrix equation, describing the generation of the matter-antimatter asymmetry, for an arbitrary choice of the right-handed (RH) neutrino masses. For hierarchical RH neutrino masses lying in the fully flavoured regimes, this reduces to multiple-stage Boltzmann equations. In this case we recover and extend results previously derived within a quantum state collapse description. We confirm the generic existence of phantom terms. However, taking into account the effect of gauge interactions, we show that they are washed out at the production with a wash-out rate that is halved compared to that one acting on the total asymmetry. In the N{sub 1}-dominated scenario they cancel without contributing to the final baryon asymmetry. In other scenarios they do not in general and they have to be taken into account. We also confirm that there is a (orthogonal) component in the asymmetry produced by the heavier RH neutrinos which completely escapes the washout from the lighter RH neutrinos and show that phantom terms additionally contribute to it. The other (parallel) component is washed out with the usual exponential factor, even for weak washout. Finally, as an illustration, we studymore » the two RH neutrino model in the light of the above findings, showing that phantom terms can contribute to the final asymmetry also in this case.« less

Authors:
 [1]; ; ;  [2]
  1. Institut de Théorie des Phénomènes Physiques, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland)
  2. School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
Publication Date:
OSTI Identifier:
22279633
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 01; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANTIMATTER; ASTROPHYSICS; ASYMMETRY; BARYONS; BOLTZMANN EQUATION; COMPARATIVE EVALUATIONS; COSMOLOGY; DENSITY MATRIX; FLAVOR MODEL; NEUTRINOS; PARTICLE PRODUCTION; PHANTOMS; QUANTUM STATES; REST MASS; VISIBLE RADIATION

Citation Formats

Blanchet, Steve, Bari, Pasquale Di, Jones, David A., and Marzola, Luca, E-mail: steve.blanchet@uam.es, E-mail: pdb1d08@soton.ac.uk, E-mail: lm10g09@soton.ac.uk, E-mail: daj1g08@soton.ac.uk. Leptogenesis with heavy neutrino flavours: from density matrix to Boltzmann equations. United States: N. p., 2013. Web. doi:10.1088/1475-7516/2013/01/041.
Blanchet, Steve, Bari, Pasquale Di, Jones, David A., & Marzola, Luca, E-mail: steve.blanchet@uam.es, E-mail: pdb1d08@soton.ac.uk, E-mail: lm10g09@soton.ac.uk, E-mail: daj1g08@soton.ac.uk. Leptogenesis with heavy neutrino flavours: from density matrix to Boltzmann equations. United States. doi:10.1088/1475-7516/2013/01/041.
Blanchet, Steve, Bari, Pasquale Di, Jones, David A., and Marzola, Luca, E-mail: steve.blanchet@uam.es, E-mail: pdb1d08@soton.ac.uk, E-mail: lm10g09@soton.ac.uk, E-mail: daj1g08@soton.ac.uk. 2013. "Leptogenesis with heavy neutrino flavours: from density matrix to Boltzmann equations". United States. doi:10.1088/1475-7516/2013/01/041.
@article{osti_22279633,
title = {Leptogenesis with heavy neutrino flavours: from density matrix to Boltzmann equations},
author = {Blanchet, Steve and Bari, Pasquale Di and Jones, David A. and Marzola, Luca, E-mail: steve.blanchet@uam.es, E-mail: pdb1d08@soton.ac.uk, E-mail: lm10g09@soton.ac.uk, E-mail: daj1g08@soton.ac.uk},
abstractNote = {Leptogenesis with heavy neutrino flavours is discussed within a density matrix formalism. We write the density matrix equation, describing the generation of the matter-antimatter asymmetry, for an arbitrary choice of the right-handed (RH) neutrino masses. For hierarchical RH neutrino masses lying in the fully flavoured regimes, this reduces to multiple-stage Boltzmann equations. In this case we recover and extend results previously derived within a quantum state collapse description. We confirm the generic existence of phantom terms. However, taking into account the effect of gauge interactions, we show that they are washed out at the production with a wash-out rate that is halved compared to that one acting on the total asymmetry. In the N{sub 1}-dominated scenario they cancel without contributing to the final baryon asymmetry. In other scenarios they do not in general and they have to be taken into account. We also confirm that there is a (orthogonal) component in the asymmetry produced by the heavier RH neutrinos which completely escapes the washout from the lighter RH neutrinos and show that phantom terms additionally contribute to it. The other (parallel) component is washed out with the usual exponential factor, even for weak washout. Finally, as an illustration, we study the two RH neutrino model in the light of the above findings, showing that phantom terms can contribute to the final asymmetry also in this case.},
doi = {10.1088/1475-7516/2013/01/041},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 01,
volume = 2013,
place = {United States},
year = 2013,
month = 1
}
  • We consider the full Boltzmann equations for standard and soft leptogenesis, instead of the usual integrated Boltzmann equations which assume kinetic equilibrium for all species. Decays and inverse decays may be inefficient for thermalising the heavy-(s)neutrino distribution function, leading to significant deviations from kinetic equilibrium. We analyse the impact of using the full kinetic equations in the case of a previously generated lepton asymmetry, and find that the washout of this initial asymmetry due to the interactions of the right-handed neutrino is larger than when calculated via the integrated equations. We also solve the full Boltzmann equations for soft leptogenesis,more » where the lepton asymmetry induced by the soft SUSY-breaking terms in sneutrino decays is a purely thermal effect, since at T = 0 the asymmetry in leptons cancels the one in sleptons. In this case, we obtain that in the weak washout regime (K ∼< 1) the final lepton asymmetry can change up to a factor four with respect to previous estimates.« less
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