Seminars and Journal Clubs

(Spooky) Axion Predictions in Grand Unified Theories

by Carlos Tamarit (Technische Universität München)

Europe/Brussels
E/3rd floor-E.349 - Seminar room (E.349) (Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve))

E/3rd floor-E.349 - Seminar room (E.349)

Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve)

30
Description

Non-supersymmetric Grand Unified models based on SO(10) × U(1)PQ or  SU(5) x U(1)PQ have all the ingredients to solve several fundamental problems of particle physics and cosmology — neutrino masses and mixing, baryogenesis, the non-observation of strong CP violation, dark matter, inflation. The axion — the pseudo Nambu-Goldstone boson arising from the spontaneous breaking of the U(1)PPeccei-Quinn symmetry — is the prime dark matter candidate in this setup. We determine the axion mass and the low energy couplings of the axion to the Standard Model particles in terms of the relevant gauge symmetry breaking scales. We work out the constraints imposed on the latter by proton decay and gauge coupling unification, paying particular attention to a minimal realistic SU(5) model in which the axion mass is directly connected to the grand-unification scale. In this case, if the flavour structure of the proton decay operators is generic,  the axion mass  is predicted to be in the window (4.8,6.6) neV. In the presence of tuning the upper bound relaxes to 330 neV. The predicted mass window will be complementarily probed by the axion dark matter experiments ABRACADABRA and CASPER-Electric, which could provide an indirect evidence for the scale of grand unification before the observation of proton decay.