New results on soft particle production in heavy-ion collisions with ATLAS

Abstract

The measurement of flow $v_2$-$v_5$ harmonics in Xe+Xe collisions at the energy of $\sqrt{s_{NN}}$ = 5.44~\TeV were recently performed in the ATLAS experiment at the LHC. Results on the $p_T$ and centrality dependence of $v_n$ harmonics are presented. A comparison of the measured $v_n$ to Pb+Pb results and theoretical predictions is shown. The data indicate stronger event-to-event fluctuations of $v_n$ harmonics in the Xe+Xe collision system as compared to Pb+Pb collisions. For Pb+Pb collisions at the energy of $\sqrt{s_{NN}}$ = 5.02 TeV, the modified Pearson's correlation coefficient for event-wise the mean transverse momentum and the square of the magnitude of flow harmonics is also. Significant, non-zero correlation coefficients for $v_2$, $v_3$ and $v_4$ harmonics are obtained. The coefficients weakly depend on the transverse momentum range of the selected particles. The coefficient for the second order harmonic is negative in peripheral events, has a significant positive value for mid-central events and drops in the most central collisions. Measured Pearson's coefficients are compared to model predictions.