The projects of Area D target to identify the foundational principles of quantum cooperative behavior. The purpose is to set the ground for a comprehensive theory that will permit to define what is quantum cooperativity in its generality, when a physical system can exhibit quantum cooperativity, how cooperativity can be designed, and which experimental setups are most promising for observing quantum cooperative behavior at the mesoscopic scale. The quantum cooperative dynamics, which are the platforms of these theoretical studies include superradiance, quantum synchronization, and quantum critical behavior in driven-dissipative systems. Projects in area D serve as pathfinder beyond the first funding period, both for exploring future experimental situations and setups, where novel cooperative effects may be prepared and studied, but also for guiding the eye for future theory projects and a more complete embedding of cooperativity in the framework of complex open manybody systems.