Living materials like bacterial colonies or confluent monolayers are collections of elementary but highly complex non-equilibrium units. Because of that, living materials are peculiar non-equilibrium systems where energy injection at the single-agent scale preserves the system to reach thermal equilibrium with the environment. From the theoretical standpoint, although peculiar, living materials are representative of a vast class of non-equilibrium systems this is because autonomous motion is the most common task performed by those elementary units [1,2]. On top of self-propulsion, local interaction rules of different kinds, from purely mechanical to biochemical and social, can trigger various collective behaviors that take the form of non-equilibrium phase transitions [3]. Those phase transitions, triggered by a hierarchy of non-equilibrium processes that involve both, interactions and fluctuations, are responsible for the structural properties of living materials, such as the unjamming transition in confluent monolayers [4,5], or for the dynamical ones, such as flocking [6,7] and directed motion [8]. 

During the last years, the theoretical exploration of living materials developed new paradigms on collective motion, such as traveling waves driven by non-reciprocal interactions [9-12], while the machinery of disordered systems proved to be very effective for our understanding of dense active systems.  Active materials can be manipulated using external fields for tuning single-agent parameters in a way to control, for instance, density fluctuations with arbitrary precision [13].  Optimal control techniques shed new light on the competition between thermal and non-equilibrium fluctuations generated by active baths [14,15]. Finally, sophisticated tools from statistical thermodynamics as the entropy production and thermodynamics uncertainty relations found a way to be measured and tested against experiments in living organisms ranging from spermatozoa to bacteria and red blood cells [16-18]. In this way, for instance, it is now possible to measure the breaking of the time-reversal symmetry on different length scales [19,20]. Those theoretical and experimental achievements call for a transverse effort to consolidate our understanding of non-equilibrium collective behavior.

Scientists working on non-equilibrium statistical mechanics with diverse backgrounds, from theoretical to computational and experimental, will join the workshop to circulate new ideas in the field of quantitative study of collective behavior in living systems. The workshop is built on the concept of a collaborative and cooperative environment where the participants can discuss and confront to define new challenges behind the most recent achievements in soft living matter.