The University of Southampton
University of Southampton Institutional Repository

Quantum Zeno effect and the impact of flavour in leptogenesis

Quantum Zeno effect and the impact of flavour in leptogenesis
Quantum Zeno effect and the impact of flavour in leptogenesis
In thermal leptogenesis, the cosmic matter–antimatter asymmetry is produced by CP violation in the decays N\to \ell+\Phi of heavy right-handed Majorana neutrinos N into ordinary leptons \ell and Higgs particles ?. If some charged-lepton Yukawa couplings are in equilibrium during the leptogenesis epoch, the \ell interactions with the background medium are flavour-sensitive and the coherence of their flavour content defined by N\to \ell+\Phi is destroyed, modifying the efficiency of the inverse decays. We point out, however, that it is not enough that the flavour-sensitive processes are fast on the cosmic expansion timescale, they must be fast relative to the N\leftrightarrow \ell+\Phi reactions lest the flavour amplitudes of \ell remain frozen by the repeated N\leftrightarrow \ell+\Phi 'measurements'. Our more restrictive requirement is significant in the most interesting 'strong wash-out case' where N\leftrightarrow \ell+\Phi is fast relative to the cosmic expansion rate. We derive conditions for the unflavoured treatment to be adequate and for flavour effects to be maximal. In this 'fully flavoured regime' a neutrino mass bound survives. To decide if this bound can be circumvented in the intermediate case, a full quantum kinetic treatment is required.
1475-7516
15-[pp]
Blanchet, S.
bd3fe15c-3ab0-4a26-8b35-390843f90b51
Di Bari, P.
3fe21e59-0eff-41bc-8faa-fdd817146418
Raffelt, G.G.
f5ace1d5-326a-4377-9650-6625dfbe60c4
Blanchet, S.
bd3fe15c-3ab0-4a26-8b35-390843f90b51
Di Bari, P.
3fe21e59-0eff-41bc-8faa-fdd817146418
Raffelt, G.G.
f5ace1d5-326a-4377-9650-6625dfbe60c4

Blanchet, S., Di Bari, P. and Raffelt, G.G. (2007) Quantum Zeno effect and the impact of flavour in leptogenesis. Journal of Cosmology and Astroparticle Physics, 2007, 15-[pp]. (doi:10.1088/1475-7516/2007/03/012).

Record type: Article

Abstract

In thermal leptogenesis, the cosmic matter–antimatter asymmetry is produced by CP violation in the decays N\to \ell+\Phi of heavy right-handed Majorana neutrinos N into ordinary leptons \ell and Higgs particles ?. If some charged-lepton Yukawa couplings are in equilibrium during the leptogenesis epoch, the \ell interactions with the background medium are flavour-sensitive and the coherence of their flavour content defined by N\to \ell+\Phi is destroyed, modifying the efficiency of the inverse decays. We point out, however, that it is not enough that the flavour-sensitive processes are fast on the cosmic expansion timescale, they must be fast relative to the N\leftrightarrow \ell+\Phi reactions lest the flavour amplitudes of \ell remain frozen by the repeated N\leftrightarrow \ell+\Phi 'measurements'. Our more restrictive requirement is significant in the most interesting 'strong wash-out case' where N\leftrightarrow \ell+\Phi is fast relative to the cosmic expansion rate. We derive conditions for the unflavoured treatment to be adequate and for flavour effects to be maximal. In this 'fully flavoured regime' a neutrino mass bound survives. To decide if this bound can be circumvented in the intermediate case, a full quantum kinetic treatment is required.

Text
JCAP.pdf - Version of Record
Restricted to Repository staff only
Request a copy

More information

Published date: 14 March 2007

Identifiers

Local EPrints ID: 152701
URI: https://eprints.soton.ac.uk/id/eprint/152701
ISSN: 1475-7516
PURE UUID: 482eec7b-a4d7-4d93-bec3-939a49b1648b

Catalogue record

Date deposited: 03 Jun 2010 09:12
Last modified: 19 Jul 2019 23:22

Export record

Altmetrics

Contributors

Author: S. Blanchet
Author: P. Di Bari
Author: G.G. Raffelt

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×