Measurement of flow harmonics correlations with mean transverse momentum in lead–lead and proton–lead collisions at √sNN−−−=5.02 TeVwith the ATLAS detector
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To assess the properties of the quark–gluon plasma formed in ultrarelativistic ion collisions, the ATLAS experiment at the LHC measures a correlation between the mean transverse momentum and the flow harmonics. The analysis uses data samples of lead–lead and proton–lead collisions obtained at the centre-of-mass energy per nucleon pair of 5.02 TeV, corresponding to total integrated luminosities of 22 μb−1 and 28 nb−1, respectively. The measurement is performed using a modified Pearson correlation coefficient with the charged-particle tracks on an event-by-event basis. The modified Pearson correlation coefficients for the 2nd-, 3rd-, and 4th-order flow harmonics are measured in the lead–lead collisions as a function of event centrality quantified as the number of charged particles or the number of nucleons participating in the collision. The measurements are performed for several intervals of the charged-particle transverse momentum. The correlation coefficients for all studied harmonics exhibit a strong centrality evolution, which only weakly depends on the charged-particle momentum range. In the proton–lead collisions, the modified Pearson correlation coefficient measured for the 2nd-order flow harmonics shows only weak centrality dependence. The lead-lead data is qualitatively described by the predictions based on the hydrodynamical model.
CitationAad G, Abbott B, Abbott DC, Abed Abud A, Abeling K, Abhayasinghe DK, Abidi SH, AbouZeid H, Abraham NL, Abramowicz H, Bjørke K, Bugge MK, Cameron DG, Catmore JR, Feigl S, Garonne V, Gramstad E, Hellesund S, Morisbak V, Oppen H, Ould-Saada F, Pedersen M, Read AL, Rye EB, Røhne OM, Sandaker H, Vadla KOH, Buanes T, Djuvsland JI, Eigen G, Fomin N, Lee GR, Lipniacka A, Martin dit Latour B, Mæland S, Stugu B, Træet AS, Abreu H, Abulaiti Y, Acharya BS, Achkar B, Adachi S, Adam L, Adam-Bourdarios C, Adamczyk L, Adamek L, Adelman J, Adersberger M, Adigüzel A, Adorni S, ATLAS C. Measurement of flow harmonics correlations with mean transverse momentum in lead–lead and proton–lead collisions at √sNN−−−=5.02 TeV with the ATLAS detector. European Physical Journal C. 2019;79:985
Copyright CERN for the benefit of the ATLAS collaboration 2019