Prof. Chengcheng Han’s team makes important progress in solving the problems of neutrino masses, inflation, and baryon asymmetry in the universe

Source: School of Physics

Edited by: Zheng Longfei, Wang Dongmei

Despite the great successes of the Standard Model (SM) at describing low energy scales, there remain many open problems that demand the existence of new physics. These issues include the mechanism for the epoch of rapid expansion in the early universe (inflation), the origin of neutrino masses, and the source of the observed baryon asymmetry. Each of these mysteries is tied to early universe physics, with any associated discoveries having significant implications for both particle physics and cosmology.

Prof. Chengcheng Han from the School of Physics at Sun Yat-sen University and his collaborators found that the introduction of the triplet Higgs to the SM provides a simple framework in which inflation, neutrino masses, and the baryon asymmetry are all explained. The neutrino masses are explained by the vacuum value of the triplet Higgs, and the inflation is driven by the mixing state of the triplet Higgs and SM doublet Higgs, while the baryon asymmetry can be generated by the Affleck-Dine mechanism. On the other hand, this model predicts that triplet Higgs dominantly decays into leptons, proving a unique signal to probe this model at colliders. At the same time, the lepton flavor violation effect induced by the triplet Higgs can also be detected by future lepton flavor violation experiments. The neutrino should be Majorana type and thus can be examined by future neutrino-less double beta decay experiments. The model also provides interesting cosmological signals which can be probed by future LiteBIRD experiment.

Sun Yat-sen University is the only corresponding affiliation of this work and Prof. Han is the only corresponding author and the joint first author (the authors of the article follow the alphabetical order). Dr. Neil D. Barrie from the institute of basic science (IBS) of Korea and Prof. Hitoshi Murayama from U.C. Berkeley and Kavli Institute for the Physics and Mathematics of the Universe of Tokyo university participate in this work. This work is supported by the Guangzhou Basic and Applied Basic Research Foundation and the Sun Yat-sen University Science Foundation. The article has been published in the journal Physical Review Letters on April 6, 2022 with the title “Affleck-Dine Leptogenesis from Higgs Inflation”.

Link to the article: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.141801