Mirror symmetry and fundamental interactions

Our modern representation of elementary processes considers that all physical phenomena result from the interplay of four fundamental interactions: the gravitational attraction, the electromagnetic force, the strong interaction and the weak interaction. Formally, the quantum mechanical description of elementary processes introduces the concept of discrete symmetry, illustrated for instance by space and time inversions. Discrete symmetries play a central role in the elaboration of theories and models, and have profound consequences in the predictions of these theories. For nearly 50 years, it has been observed that, of the four fundamental interactions, only the weak interaction violates mirror symmetry, and all observations so far indicate that it does so in a so-called maximal way. Despite overwhelming evidence of mirror-symmetry breaking, the search for a possibly underlying left–right symmetry has been pursued for many years by dedicated experiments. In this paper we review the context of mirror symmetry breaking in the weak interaction, we describe its interpretation in the framework of the standard model of particle physics and describe current efforts to identify the restoration of the left–right symmetry.