Smallest drop of QGP: Thermodynamic properties ofp-Pbcollisions

Abstract

The extreme temperature and density conditions that arise in ultrarelativistic collisions of heavy nuclei enable the formation of the most fundamental fluid in the universe, the deconfined phase of quantum chromodynamics known as quark-gluon plasma. Despite the extensive experimental evidence gathered over the last decade for the production of quark-gluon plasma in colliding systems such as Au-Au and Pb-Pb, the formation of quark-gluon plasma in the collision of smaller systems such as $p$-Pb remains an open question. In this study, we describe the evolution of matter formed in $p$-Pb collisions at 5.02 TeV using a state-of-the-art hybrid model based on viscous relativistic hydrodynamics. We study the thermodynamic properties of the medium and the final state observables. Our results are compared with experimental data and first-principles lattice quantum chromodynamics calculations. The results support the formation of a collective phase of strongly interacting matter in high-multiplicity $p$-Pb collisions.