# Chemical Equilibration in Hadronic Collisions

Kurkela, Aleksi (Theoretical Physics Department, CERN, Geneva, Switzerland and Faculty of Science and Technology, University of Stavanger, 4036 Stavanger, Norway) ; Mazeliauskas, Aleksas (Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany)

11 April 2019

Abstract: We study chemical equilibration in out-of-equilibrium quark-gluon plasma using the first principles method of QCD effective kinetic theory, accurate at weak coupling. In longitudinally expanding systems—relevant for relativistic nuclear collisions—we find that for realistic couplings chemical equilibration takes place after hydrodynamization, but well before local thermalization. We estimate that hadronic collisions with final state multiplicities $d{N}_{\mathrm{ch}}/d\eta \gtrsim {10}^{2}$ live long enough to reach approximate chemical equilibrium, which is consistent with the saturation of strangeness enhancement observed in proton-proton, proton-nucleus, and nucleus-nucleus collisions.

Published in: Physical Review Letters 122 (2019)