Guwahati: Researchers at the Indian Institute of Technology (IIT), Guwahati, in collaboration with international scientists, have shed light on the matter-antimatter imbalance in the Universe. The study addresses a longstanding mystery concerning dark matter and Baryon Asymmetry in the Universe (BAU).
Published in Physical Review D and funded by the Science and Engineering Research Board (SERB), the research informs that only about 5% of the Universe consists of visible or baryonic matter, while the remainder is dark matter—a substance that does not emit light.
Debasish Borah, Associate Professor at IIT Guwahati, led the team that proposed a novel scenario in which baryon asymmetry arose from the decay of dark matter. Contrary to the traditional view of dark matter stability, specific temperature-induced corrections to its mass render its decay energetically feasible in the early Universe.
International collaborators Arnab Dasgupta, Matthew Knauss, and Rishav Roshan from institutions in the US and South Korea played an integral part in the study. The proposed model suggests that dark matter transforms into regular matter due to temperature effects, generating an imbalance between matter and antimatter.
“In our model of the early Universe, dark matter transforms into regular matter due to temperature effects, generating an imbalance between matter and antimatter. We first propose a unique type of dark matter, a singlet fermion, influenced by a scalar field. The associated scalar field may act as an inflation during the Universe’s early expansion or can lead to a strong first order phase transition,” Borah said.
In this model, dark matter partially decays into ordinary matter in the early Universe, contributing to the creation of the BAU. As the Universe cools, dark matter stabilizes, leaving a residue observed as dark matter today. This mechanism not only elucidates dark matter but also influences the creation of visible matter, impacting matter-antimatter asymmetry in the Universe, he added.
