2025/06/21 by Nayak, Kishora, Bairathi, Vipul
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2506.17763
The directed flow (v1) of charged hadrons (h±) in symmetric collision systems (O+O, Cu+Cu, Zr+Zr, Ru+Ru, Au+Au, and U+U) at √sNN = 200 GeV using string-melting version of A Multiphase Transport (AMPT-SM) model is reported. The v1 as a function of pseudo-rapidity (η) is obtained for transverse momentum (pT) ranges of 0.2-2.0 GeV/c and 2.0-5.0 GeV/c. The dependence of v1-slope (dv1/dη) at mid-rapidity on pT range, collision centrality, and system size are discussed particularly in the context of the hard-soft asymmetry in the flow profiles of produced particles. In the AMPT-SM model, a system size independence of the magnitude of dv1/dη between Cu+Cu and Au+Au collisions at low-pT is observed, and this finding is similar to the observation from the STAR experiment at √sNN = 200 GeV. In contrast, a strong centrality and system size dependence, with the opposite sign of dv1/dη, is found for the high-pT charged hadrons. The AMPT-SM model demonstrates a clear violation of the expected scaling of charged hadrons (dv1/dη)/A1/3 across different colliding systems.