Proton-proton interactions and onset of deconfinement

Abstract

The experiment of the NA61/SHINE Collaboration at the CERN SPS is performing a unique study of the phase diagram of strongly interacting matter by varying collision energy and nuclear mass number of colliding nuclei. In central $\mathrm{Pb}+\mathrm{Pb}$ collisions, the experiment of the NA49 Collaboration found structures in the energy dependence of several observables in the energy range of the CERN SPS that had been predicted for the transition to a deconfined phase. New measurements of the NA61/SHINE Collaboration find intriguing similarities in $p+p$ interactions for which no deconfinement transition is expected at the energies of the SPS. Possible implications will be discussed.