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Open AccessArticle

Flavour Composition and Entropy Increase of Cosmological Neutrinos After Decoherence

1
Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
2
Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), 09210-580 Santo André, Brazil
3
Departamento de Física, Universidade Federal de Ouro Preto (UFOP), 35400-000 Ouro Preto MG, Brazil
*
Author to whom correspondence should be addressed.
Universe 2019, 5(10), 203; https://doi.org/10.3390/universe5100203
Received: 30 July 2019 / Revised: 17 September 2019 / Accepted: 19 September 2019 / Published: 25 September 2019
We propose that gravitational interactions of cosmic neutrinos with the statistically homogeneous and isotropic fluctuations of space-time lead to decoherence. This working hypothesis, which we describe by means of a Lindblad operator, is applied to the system of two- and three-flavour neutrinos undergoing vacuum oscillations and the consequences are investigated. As a result of this decoherence we find that the neutrino entropy would increase as a function of initial spectral distortions, mixing angles and charge-parity (CP)-violation phase. Subsequently we discuss the chances to discover such an increase observationally (in principle). We also present the expected flavour composition of the cosmic neutrino background after decoherence is completed. The physics of two- or three-flavour oscillation of cosmological neutrinos resembles in many aspects two- or three-level systems in atomic clocks, which were recently proposed by Weinberg for the study of decoherence phenomena. View Full-Text
Keywords: cosmology; neutrino oscillations; cosmic neutrino background cosmology; neutrino oscillations; cosmic neutrino background
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Boriero, D.; Schwarz, D.J.; Velten, H. Flavour Composition and Entropy Increase of Cosmological Neutrinos After Decoherence. Universe 2019, 5, 203.

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