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Journal article 1384 views 152 downloads

Leptogenesis from loop effects in curved spacetime

Jamie I McDonald, Graham Shore

Journal of High Energy Physics, Volume: 1604, Start page: 030

Swansea University Author: Graham Shore

DOI (Published version): 10.1007/JHEP04(2016)030

Abstract

We describe a new mechanism -- radiatively-induced gravitational leptogenesis -- for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove...

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Published in: Journal of High Energy Physics
Published: 2016
Online Access: https://arXiv:1512.02238 [hep-ph]
URI: https://cronfa.swan.ac.uk/Record/cronfa25650
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Abstract: We describe a new mechanism -- radiatively-induced gravitational leptogenesis -- for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove this is forbidden in flat space by CPT and translation symmetry. This generates a curvature-dependent chemical potential for leptons, allowing a matter-antimatter asymmetry to be generated in thermal equilibrium in the early Universe. The time-dependent dynamics necessary for leptogenesis is provided by the interaction of the virtual self-energy cloud of the leptons with the expanding curved spacetime background, which violates the strong equivalence principle and allows a distinction between matter and antimatter. We show here how this mechanism is realised in a particular BSM theory, the see-saw model, where the quantum loops involve the heavy sterile neutrinos responsible for light neutrino masses. We demonstrate by explicit computation of the relevant two-loop Feynman diagrams how the size of the radiative corrections relevant for leptogenesis becomes enhanced by increasing the mass hierarchy of the sterile neutrinos, and show that for realistic phenomenological parameters this mechanism can generate the observed baryon-to-photon ratio of the Universe.
Item Description: JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0
College: Faculty of Science and Engineering
Start Page: 030

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