On the origin of matter in the Universe

Abstract

The understanding of the physical processes that lead to the origin of matter in the early Universe, creating both an excess of matter over anti-matter and a dark matter abundance that survived until the present, is one of the most fascinating challenges in modern science. The problem cannot be addressed within our current description of fundamental physics and, therefore, it currently provides a very strong evidence of new physics. Solutions can either reside in a modification of the standard model of elementary particle physics or in a modification of the way we describe gravity, based on general relativity, or at the interface of both. We will mainly discuss the first class of solutions. Traditionally, models that separately explain either the matter–antimatter asymmetry of the Universe or dark matter have been proposed. However, in the last years there has also been an accreted interest and intense activity on scenarios able to provide a unified picture of the origin of matter in the early universe. In this review we discuss some of the main ideas emphasising primarily those models that have more chances to be experimentally tested during next years. Moreover, after a general discussion, we will focus on extensions of the standard model that can also address neutrino masses and mixing. Since this is currently the only evidence of physics beyond the standard model coming directly from particle physics experiments, it is then reasonable that such extensions might also provide a solution to the problem of the origin of matter in the universe.