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arXiv · 2209.04096

Enhanced pion-to-proton ratio at the onset of the QCD phase transition

Thiranat Bumnedpan·Jan Steinheimer·Marcus Bleicher·Ayut Limphirat·Christoph Herold
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Abstract

The pion-to-proton ratio is identified as a potential signal for a non-equilibrium first-order chiral phase transition in heavy-ion collisions, as the pion multiplicity is directly related to entropy production. To showcase this effect, a non-equilibrium Bjorken expansion starting from realistic initial conditions along a Taub adiabat is used to simulate the entropy production. Different dynamical criteria to determine the final entropy-per-baryon number are investigated and matched to a hadron resonance gas model along the chemical freeze out curve to obtain the final pion and proton numbers. We detect a strong enhancement of their multiplicity ratio at the energies where the system experiences a strong phase transition as compared to a smooth crossover which shows almost no enhancement.

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Thiranat Bumnedpan, Jan Steinheimer, Marcus Bleicher, Ayut Limphirat, Christoph Herold. 2022-09-09. Enhanced pion-to-proton ratio at the onset of the QCD phase transition. https://doi.org/10.1016/j.physletb.2022.137537

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