Dynamical Coulomb effects on charged-pion HBT-radius splitting in central Au+Au collisions at few-GeV energies
Year: 2026
Type: article
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.
Source: Physics Letters B
Authors: Pengcheng Li, Yongjia Wang, Qingfeng Li
Institution: Huzhou Normal University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7214043294