2023/12/24 by Jin-Wen Kang, Sa Wang, Kang, Jin-Wen +5
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Nuclear Theory (nucl-th) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2312.15518
openalex publication_date 2023/12/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
This paper presents a phenomenological study on the angle between the Standard and the Winner-Take-All (WTA) jet axes (ΔR\rm axis\rm WTA-Std) in high-energy nuclear collisions. The p+p baseline is provided by the Pythia8 event generator. The in-medium jet propagation is simulated by the linear Boltzmann transport (LBT) model, which considers both the elastic and inelastic jet-medium interactions. Our theoretical results calculated by the LBT model show that the ΔR\rm axis\rm WTA-Std distribution in Pb+Pb at √(s)=5.02 TeV is narrower than that in p+p, which agrees well with the recent ALICE measurements. The narrowing of ΔR\rm axis\rm WTA-Std seems to violate the pT-broadening nature of the jet quenching effect, usually explained by the influence of "selection bias". However, the physical details still need to be fully understood. Utilizing a matching-jet method to track the jet evolution in the QGP to remove the selection bias in the Monte Carlo simulations, we observe that the ΔR\rm axis\rm WTA-Std distribution becomes broader due to the jet-medium interactions. At the same time, by rescaling the quark/gluon-jet fractions in Pb+Pb collisions to be the same as that in p+p, we find that the fraction change may not significantly influence the modification pattern of jet ΔR\rm axis\rm WTA-Std. On the other hand, the selected jet sample in A+A collisions has a significantly narrower initial ΔR\rm axis\rm WTA-Std distribution than the p+p baseline, and such a biased comparison between p+p and A+A conceals the actual jet-broadening effect in the experimental measurements. The investigations presented in this paper will deepen our understanding of the relationship between the actual intra-jet modifications in the QGP and the experimental observations.