[Research provides new clues to explain the asymmetry between matter and antimatter in the universe] On October 25, researchers from the University of Southampton in the United Kingdom and other institutions proposed that a heavy neutrino that was often ignored in previous theoretical studies may have affected the evolution of the early universe. This provides new clues to explain why there is more matter than antimatter. A new study from the school, in collaboration with researchers at the Indian Institute of Technology Kanpur, focuses on a type of "decoupled" heavy neutrino in theoretical models. The heavy neutrino is a theoretically hypothesized particle that has not yet been directly discovered experimentally. The heavy neutrino is considered a "relative" of the neutrino, "decoupled" meaning that it no longer interacts with other particles. In the past, relevant theoretical studies often ignored this particle, thinking that it had a limited impact on the formation of asymmetry between matter and antimatter. This study suggests that "decoupled" heavy neutrinos decay extremely slowly. As the universe gradually cooled after the Big Bang, it may have survived long enough to briefly dominate the energy density of the universe, triggering a matter-dominated phase, thus affecting the formation process of asymmetry between matter and antimatter. (Xinhua News Agency)