Leptogenesis with high-scale electroweak symmetry breaking and an extended Higgs sector

Abstract

We propose a new scenario for baryogenesis through leptogenesis, where the CP phase relevant for leptogenesis is connected directly to the Pontecorvo-Maki-Nakagawa-Sakada (PMNS) phase(s) in the light neutrino mixing matrix. The scenario is realized in the case when only one CP phase appears in the full theory, originating from the complex vacuum expextation value of a standard model singlet field. In order to realize this scheme, the electroweak symmetry is required to be broken during the leptogenesis era, and a new loop diagram with an intermediate W boson exchange including the low-energy neutrino mixing matrix should play the dominant contribution to the CP violation for leptogenesis. In this article, we discuss the new basic mechanism, which we call type-II leptogenesis, and give an estimate for maximally reachable baryon asymmetry depending on the PMNS phases