Physics Theory Seminar with Debasish Borah on Matter-antimatter asymmetry from forbidden decays

The visible part of the present Universe is composed of matter only with negligible trace of antimatter. However, matter and antimatter are two sides of the same coin, and the Big Bang should not have had a preference for creating one type over another. Therefore, the observed dominance of matter over antimatter in the present Universe has led to a longstanding puzzle in particle physics and cosmology. One of the appealing solutions to this puzzle is Baryogenesis/leptogenesis where out-of-equilibrium and CP violating decay of a heavy particle generates such asymmetry. This talk will discuss the impact of a first-order phase transition in the early Universe controlling the decay of such a heavy particle thereby allowing it to play additional roles like cold dark matter in the Universe. Depending upon the specific model implementation, additional phenomenological implications like primordial black holes, large neutrino asymmetry can also arise.

This lecture was made possible by the William C. Ferguson Fund.