Dynamical Coulomb effects on charged-pion HBT-radius splitting in central Au+Au collisions at few-GeV energies
Abstract
The pair transverse momentum (kT) and collision-energy (√(sNN)) dependent difference between π+π+ and π−π− femtoscopic correlations was observed by the HADES and STAR Collaborations. We investigate how much of the observed splitting can be accounted for by Coulomb dynamics in 0-10\% central Au+Au collisions at √(sNN)=2.42-5.2 GeV. Using the UrQMD model and the CRAB programme, three transport scenarios that successively include baryon-baryon, baryon-meson, and meson-meson Coulomb interactions are considered. In a separate calculation based on the baryon-baryon reference, we reconstruct the time-dependent effective charge Zeff(t) and radius Reff(t) of the residual charged source and propagate each pion from its individual last strong-interaction point through the evolving field. The calculations reproduce the main kT and √(sNN) dependences of the radii. Baryon--meson Coulomb interactions generate most of the additional charge splitting in the microscopic calculation. The residual-source treatment also enhances the longitudinal and sideward radius ratios relative to the reference, whereas the outward ratio changes little, and the enhancement generally decreases with increasing √(sNN). Within the present framework, this contribution does not fully account for the data, motivating further investigation of the charged-source geometry and its interplay with strong-interaction dynamics.
Versions
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BibTeX
@misc{li2026dynamical,
title = {{Dynamical Coulomb effects on charged-pion HBT-radius splitting in central Au+Au collisions at few-GeV energies}},
author = {Pengcheng Li and Yongjia Wang and Qingfeng Li},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.23422},
eprint = {2609.23422},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.23422},
note = {CC0},
}
RIS
TY - UNPB
TI - Dynamical Coulomb effects on charged-pion HBT-radius splitting in central Au+Au collisions at few-GeV energies
AU - Pengcheng Li
AU - Yongjia Wang
AU - Qingfeng Li
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2609.23422
UR - https://arxiv.org/abs/2609.23422
AB - The pair transverse momentum (k_T) and collision-energy (√(s_NN)) dependent difference between π^+π^+ and π^−π^− femtoscopic correlations was observed by the HADES and STAR Collaborations. We investigate how much of the observed splitting can be accounted for by Coulomb dynamics in 0-10\% central Au+Au collisions at √(s_NN)=2.42-5.2 GeV. Using the UrQMD model and the CRAB programme, three transport scenarios that successively include baryon-baryon, baryon-meson, and meson-meson Coulomb interactions are considered. In a separate calculation based on the baryon-baryon reference, we reconstruct the time-dependent effective charge Z_eff(t) and radius R_eff(t) of the residual charged source and propagate each pion from its individual last strong-interaction point through the evolving field. The calculations reproduce the main k_T and √(s_NN) dependences of the radii. Baryon--meson Coulomb interactions generate most of the additional charge splitting in the microscopic calculation. The residual-source treatment also enhances the longitudinal and sideward radius ratios relative to the reference, whereas the outward ratio changes little, and the enhancement generally decreases with increasing √(s_NN). Within the present framework, this contribution does not fully account for the data, motivating further investigation of the charged-source geometry and its interplay with strong-interaction dynamics.
ER -