Hadronic rescattering effects on net-proton cumulants from functional renormalization group calculations
Abstract
Net-proton cumulants in the Beam Energy Scan region of heavy-ion collisions are widely used to probe critical fluctuations associated with the conjectured critical endpoint of Quantum Chromodynamics (QCD). Most existing studies, however, concentrate on the initial-state or phase-transition contributions, while the impact of hadronic rescattering on these observables has not been fully quantified. To address this gap, we construct event-by-event proton and antiproton distributions from functional renormalization group (fRG) cumulants using the maximum entropy principle, and propagate the resulting particles through the hadronic transport model SMASH in a simplified spherical evolution setup. We systematically investigate how the hadronic cascade modifies net-proton cumulants at collision energies √(sNN)=3.0, 3.9, 4.9, 7.2, and 7.7~GeV. In the canonical-ensemble framework, which enforces exact net-baryon number conservation, the higher-order cumulant signal---in particular the ratio C4/C2 at √(sNN)=4.9~GeV---is strongly reduced during the early stage of the cascade; the suppression of C4/C2 reaches approximately 20%. The non-monotonic energy dependence inherited from the fRG input survives the hadronic evolution, but its magnitude is substantially modified. These results demonstrate that hadronic rescattering provides a non-negligible background effect that must be accounted for when extracting QCD critical-point signals from experimental data.
Related
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BibTeX
@misc{lin2026hadronic,
title = {{Hadronic rescattering effects on net-proton cumulants from functional renormalization group calculations}},
author = {Qianru Lin and Shi Yin and Jianing Li and Hannah Elfner and Fabian Rennecke and Long-Gang Pang and Jan M. Pawlowski},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.28299},
eprint = {2608.28299},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.28299},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Hadronic rescattering effects on net-proton cumulants from functional renormalization group calculations
AU - Qianru Lin
AU - Shi Yin
AU - Jianing Li
AU - Hannah Elfner
AU - Fabian Rennecke
AU - Long-Gang Pang
AU - Jan M. Pawlowski
PY - 2026
DA - 2026/08/28
PB - arXiv
DO - 10.48550/arxiv.2608.28299
UR - https://arxiv.org/abs/2608.28299
AB - Net-proton cumulants in the Beam Energy Scan region of heavy-ion collisions are widely used to probe critical fluctuations associated with the conjectured critical endpoint of Quantum Chromodynamics (QCD). Most existing studies, however, concentrate on the initial-state or phase-transition contributions, while the impact of hadronic rescattering on these observables has not been fully quantified. To address this gap, we construct event-by-event proton and antiproton distributions from functional renormalization group (fRG) cumulants using the maximum entropy principle, and propagate the resulting particles through the hadronic transport model SMASH in a simplified spherical evolution setup. We systematically investigate how the hadronic cascade modifies net-proton cumulants at collision energies √(s_NN)=3.0, 3.9, 4.9, 7.2, and 7.7~GeV. In the canonical-ensemble framework, which enforces exact net-baryon number conservation, the higher-order cumulant signal---in particular the ratio C_4/C_2 at √(s_NN)=4.9~GeV---is strongly reduced during the early stage of the cascade; the suppression of C_4/C_2 reaches approximately 20%. The non-monotonic energy dependence inherited from the fRG input survives the hadronic evolution, but its magnitude is substantially modified. These results demonstrate that hadronic rescattering provides a non-negligible background effect that must be accounted for when extracting QCD critical-point signals from experimental data.
ER -