European Physical Journal C: Particles and Fields (Oct 2022)

The high-density equation of state in heavy-ion collisions: constraints from proton flow

  • Jan Steinheimer,
  • Anton Motornenko,
  • Agnieszka Sorensen,
  • Yasushi Nara,
  • Volker Koch,
  • Marcus Bleicher

DOI
https://doi.org/10.1140/epjc/s10052-022-10894-w
Journal volume & issue
Vol. 82, no. 10
pp. 1 – 12

Abstract

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Abstract A set of different equations of state is implemented in the molecular dynamics part of a non-equilibrium transport simulation (UrQMD) of heavy-ion collisions. It is shown how different flow observables are affected by the density dependence of the equation of state. In particular, the effects of a phase transition at high density are explored, including an expected reduction in mean $$m_T$$ m T . We also show that an increase in $$v_2$$ v 2 is characteristic for a strong softening of the equation of state. The phase transitions with a low coexistence density, $$n_{\text {CE}}<4 n_0$$ n CE < 4 n 0 , show a distinct minimum in the slope of the directed flow as a function of the beam energy, which would be a clear experimental signal. By comparing our results with experimental data, we can exclude any strong phase transition at densities below $$4n_0$$ 4 n 0 .