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arXiv · 2107.08812

The role of proton-antiproton regeneration in the late stages of heavy-ion collisions

Oscar Garcia-Montero·Jan Staudenmaier·Anna Schäfer·Juan M. Torres-Rincon·Hannah Elfner
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Abstract

We investigate the long-standing question of the effect of proton-antiproton annihilation on the (anti-)proton yield, while respecting detailed balance for the 5-body back-reaction for the first time in a full microscopic description of the late stages of heavy-ion collisions. This is achieved by employing a stochastic collision criterion in a hadronic transport approach (SMASH), which allows to treat arbitrary multi-particle reactions. It is used to account for the regeneration of (anti-)protons via $5π\rightarrow p\bar{p}$. Our results show that a back-reaction happens for a fraction of 15-20\% of all annihilations. Within a viscous hybrid approach Au+Au/Pb+Pb collisions from $\sqrt{s_{NN}}=17.3$ GeV$-5.02$ TeV are investigated and the quoted fraction is independent of the beam energy or centrality of the collision. Taking the back-reaction into account results in regeneration of half of the (anti-)proton yield that is lost due to annihilations at midrapidity. We also find that, concerning the multiplicities, treating the back-reaction as a chain of 2-body reactions is equivalent to a single 5-to-2 reaction.

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Oscar Garcia-Montero, Jan Staudenmaier, Anna Schäfer, Juan M. Torres-Rincon, Hannah Elfner. 2021-07-19. The role of proton-antiproton regeneration in the late stages of heavy-ion collisions. https://doi.org/10.1103/physrevc.105.064906

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