Multi-harmonic correlations of different flow amplitudes in Pb-Pb collisions at $\sqrt{s_{_{\rm NN}}}=2.76$ TeV

The event-by-event correlations between three flow amplitudes are measured for the first time in Pb--Pb collisions, using higher-order Symmetric Cumulants. We find that different three-harmonic correlations develop during the collective evolution of the medium, when compared with correlations that exist in the initial state. These new results cannot be interpreted in terms of previous lower-order flow measurements, since contributions from two-harmonic correlations are explicitly removed in the new observables. Comparison with Monte Carlo simulations provides new and independent constraints for the initial conditions and system properties of nuclear matter created in heavy-ion collisions.

 

Phys. Rev. Lett. 127 (2021) 092302
HEP Data
e-Print: arXiv:2101.02579 | PDF | inSPIRE
CERN-EP-2021-005
Figure group

Figure 1

Centrality dependence of SC(2,3,4), SC(2,3,5), SC(2,4,6) and SC(3,4,5) (a) and of NSC(2,3,4) and NSC(2,3,5) (b) in Pb--Pb collisions at $\sqrt{s_{_{\rm NN}}}=2.76$~TeV. The statistical (systematic) uncertainties are shown with the lines (boxes). The data points are shifted horizontally for visibility.

Figure 2

Predictions from the hydrodynamical models for the centrality dependence for the SC($k,l,m$) [panels (a), (c), (e) and (f)] and NSC($k,l,m$) [panels (b) and (d)] in Pb--Pb collisions at $\sqrt{s_{_{\rm NN}}}=2.76$~TeV. The statistical uncertainties are shown with coloured bands. The predictions are compared with the ALICE results from Fig.~\ref{s:Results_fig1} shown with red markers. The bands represent the statistical uncertainty of each model.