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  • Exploring origins for corre...
    Lim, S. H.; Nagle, J. L.

    Physical review. C, 06/2021, Letnik: 103, Številka: 6
    Journal Article

    High statistics data sets from experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) with small and large collision species have enabled a wealth of new flow measurements, including the event-by-event correlation between observables. One exciting such observable $ρ(v^2_n, p_T)$ gauges the correlation between the mean transverse momentum of particles in an event and the various flow coefficients (vn) in the same event P. Bozek, Phys. Rev. C 93, 044908 (2016). Recently it has been proposed that very low multiplicity events may be sensitive to initial-state glasma correlations G. Giacalone, B. Schenke, and C. Shen, Phys. Rev. Lett. 125, 192301 (2020) rather than flow-related dynamics. We find utilizing the ip-jazma framework that the color domain explanation for the glasma results are incomplete. We then explore predictions from pythia8, and the version for including nuclear collisions called pythia-angantyr, which have only nonflow correlations, and from the ampt model which has both nonflow and flow-type correlations. We find that pythia-angantyr has nonflow contributions to $ρ(v^2_n, p_T)$ in p + O, p + Pb, and O + O collisions that are positive at low multiplicity and comparable to the glasma correlations. It is striking that in pythia8 in p + p collisions there is actually a sign change from positive to negative $ρ(v^2_n, p_T)$ as a function of multiplicity. The ampt results match the experimental data general trends in Pb+Pb collisions at the LHC, except at low multiplicity where ampt has the opposite sign. In p + Pb collisions, ampt has the opposite sign from experimental data and we explore this within the context of parton geometry. Predictions for p + O, O + O, and Xe + Xe are also presented.