Many new particles, mostly hadrons, are produced in high-energy collisions between atomic nuclei. The most popular models describing the hadron production process are based on the creation, evolution, and decay of resonances, strings, or quark-gluon plasma. The validity of these models is under vivid discussion, and it seems that a common framework for this discussion is missing. Here we introduce the diagram of high-energy nuclear collisions, where domains of the dominance of different hadron-production processes in the laboratory-controlled parameters, the collision energy, and the nuclear-mass number of colliding nuclei are indicated.
We argue the recent experimental results, in particular by NA61/SHINE, locate boundaries between the domains, allowing for the first time to sketch an example diagram. Finally, we discuss the immediate implications for experimental measurements and model development following the sketch.