Tricritical behaviour in dynamical phase transitions

Classical statistical mechanics is pivotal for our understanding of equilibrium systems. Yet it mostly fails to address dynamical observables which are key for both equilibrium and far-from-equilibrium systems. In this talk, I will discuss the importance of three such observables: the activity in glassy systems, the integrated current in transport phenomena, and the entropy production in active matter. I will show how these can be addressed within the perspective of large deviation theory and present our findings of an interesting and novel scenario for dynamical phase transitions. It is characterized by the pairwise meeting of first- and second-order bias-induced phase transition curves at two tricritical points. A simple, general criterion predicts its appearance and is complemented by an exact Landau theory for the tricritical behavior.