Leptogenesis and neutrino oscillations in the classically conformal standard model with the Higgs portal

• Published in: The journal of high energy physics Vol. 2013; no. 10; pp. 1 - 26
• Main Authors: Khoze, Valentin V., Ro, Gunnar
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2013; Springer Nature B.V
• Subjects: Asymmetry; Baryons; Broken symmetry; Classical and Quantum Gravitation; Elementary Particles; High energy physics; Inclusions; Neutrinos; Oscillations; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Relativity Theory; Scale (ratio); Standard model (particle physics); String Theory; Spontaneous Symmetry Breaking; Beyond Standard Model; Higgs Physics
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP10(2013)075

A bstract The Standard Model with an added Higgs portal interaction and no explicit mass terms is a classically scale-invariant theory. In this case the scale of electroweak symmetry breaking can be induced radiatively by the Coleman-Weinberg mechanism operational in a hidden sector, and then transmitted to the Standard Model through the Higgs portal. The smallness of the generated values for the Higgs vev and mass, compared to the UV cutoff of our classically scale-invariant effective theory, is naturally explained by this mechanism. We show how these classically conformal models can generate the baryon asymmetry of the Universe without the need of introducing mass scales by hand or their resonant fine-tuning. The minimal model we consider is the Standard Model coupled to the Coleman-Weinberg scalar field charged under the U(1) B−L gauge group. Anomaly cancellation requires automatic inclusion of three generations of right-handed neutrinos. Their GeV-scale Majorana masses are induced by the Coleman-Weinberg field and lead to the generation of active neutrino masses through the standard see-saw mechanism. Leptogenesis occurs via flavour oscillations of right-handed sterile neutrinos and is converted to the baryon asymmetry by electroweak sphalerons.