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v3.3.3
Speaker: Julio Leite, IFIC, Valencia
Title: Dirac neutrinos in WIMP and axion dark matter scenarios
Abstract:
We propose two scenarios where the smallness of neutrino masses is closely linked to the existence of dark matter (DM). Both cases are understood within the framework of (TeV-scale) gauge extensions of the Standard Model, known as 3-3-1 models. In the first case, neutrino masses only appear at loop level and are mediated by WIMP dark matter candidates. The stability of DM is linked to the Dirac nature of neutrinos, which results from an unbroken B − L gauge symmetry. In the second model, the Peccei-Quinn (PQ) solution to the strong-CP problem is implemented, and the associated axion field can play the role of DM. Neutrino masses arise from a type-I Dirac seesaw mechanism, suppressed by the ratio of 3-3-1 and PQ scales, suggesting the existence of new physics at a moderate 3-3-1 scale. Novel features include an enhanced axion coupling to photons when compared to the DFSZ axion, as well as flavour-changing axion couplings to quarks.