Dynamical Coulomb effects on charged-pion HBT-radius splitting in central Au+Au collisions at few-GeV energies
Abstract
The pair transverse momentum ( k T ) and collision-energy ( s N N ) 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 N N = 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 N N 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 N N . 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
@article{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},
journal = {Physics Letters B},
year = {2026},
month = oct,
doi = {10.1016/j.physletb.2026.141081},
url = {https://linkinghub.elsevier.com/retrieve/pii/S0370269326009317},
note = {CC BY 4.0},
}
RIS
TY - JOUR
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 - 2026/10/30
JO - Physics Letters B
DO - 10.1016/j.physletb.2026.141081
UR - https://linkinghub.elsevier.com/retrieve/pii/S0370269326009317
AB - The pair transverse momentum ( k T ) and collision-energy ( s N N ) 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 N N = 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 N N 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 N N . 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.
SN - 0370-2693
SN - 1873-2445
ER -