Evolution of antibaryon abundances in the early Universe and in heavy-ion collisions

Abstract

We study the kinetics of antibaryon production and annihilation in an expanding system, assuming that it is spatially homogeneous and chemically equilibrated at the initial stage. By solving simplified rate equations for (anti)baryon abundances we study the deviations from chemical equilibrium at late stages. The calculations are done for different expansion rates and net-baryon-to-entropy ratios, covering the conditions from early Universe to heavy-ion collisions. Our analysis includes both stable (anti)baryons and resonances. We conclude that residual antibaryon abundances are very sensitive to the time scales of expansion. Our calculations naturally explain noticeable deviations of antiproton-to-pion and proton-to-pion ratios observed in nuclear collisions at the LHC energy from the thermal model predictions. We conclude that at high bombarding energies the chemical freeze-out of (anti)baryons should occur at lower temperatures as compared to mesons.

24 pages, 9 figures

References in corpus (5)

• Pion, kaon, and proton production in central Pb-Pb Collisions at $\sqrt{s_{NN}}=2.76$ TeV
• Non-thermal p/pi ratio at LHC as a consequence of hadronic final state interactions
• Centrality dependence of proton and antiproton spectra in Pb+Pb collisions at 40A GeV and 158A GeV measured at the CERN SPS
• Longitudinal fluid dynamics for ultrarelativistic heavy-ion collisions
• 1+1 Dimensional Hydrodynamics for High-energy Heavy-ion Collisions

Cited by in corpus (5)

• Influence of the hadronic phase on observables in ultrarelativistic heavy ion collisions
• New scenarios for hard-core interactions in a hadron resonance gas
• Lorentz invariant relative velocity and relativistic binary collisions
• Entropy production in chemically non-equilibrium quark-gluon plasma created in central Pb+Pb collisions at LHC energies
• Centrality dependence of proton and light nuclei yields as a consequence of baryon annihilation in the hadronic phase