/ nucl-th arXiv:1504.03992

Robustness of the Baryon-Stopping Signal for the Onset of Deconfinement in Relativistic Heavy-Ion Collisions

Ivanov, Yu. B. (Moscow Phys. Eng. Inst.) ; Blaschke, D. (Wroclaw U.)

Pages: 7

Abstract: The impact of the experimental acceptance, i.e. transverse-momentum ($p_T$) cut-off and limited rapidity region, on the earlier predicted irregularity in the excitation function of the baryon stopping is studied. This irregularity is a consequence of the onset of deconfinement occurring in the compression stage of a nuclear collision and manifests itself as a wiggle in the excitation function of the reduced curvature ($C_y$) of the net-proton rapidity distribution at midrapidity. It is demonstrated that the wiggle is a very robust signal of a first-order phase transition that survives even under conditions of a very limited acceptance. At the same time the $C_y$ for pure hadronic and crossover transition scenarios become hardly distinguishable, if the acceptance cuts off too much of the low-$p_T$ proton spectrum and/or puts too narrow rapidity window around midrapidity. It is found that the shape of the net-proton rapidity distribution near midrapidity depends on the $p_T$ cut-off. This implies that the measurements should be taken at the same acceptance for all collision energies in order to reliably conclude on the presence or absence of the irregularity.

Note: 7 pages, 4 figures. arXiv admin note: text overlap with arXiv:1211.2579, arXiv:1302.5766

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