New ATLAS results on integrated flow and correlations between flow harmonics in Pb+Pb collisions

The measurement of centrality and pseudorapidity dependence of the $p_{T}$-integrated flow harmonics, $v_{2}$ up to $v_{5}$, in Pb+Pb collisions at $\sqrt {s_{NN}}$=2.76 TeV with the ATLAS detector at the LHC are presented. These measurements give a clear picture of the average geometry as well as fluctuations in it. These measurements are extended to include the correlations between flow harmonics of different order, which are sensitive to the quantum fluctuations in the initial geometry and hydrodynamic response in the final state collective expansion. In the last QM conference, ATLAS showed the first results on $v_2-v_n$ (n=2-5) correlation obtained by varying the event ellipticity in narrow centrality intervals using an event-shape engineering technique. That measurement has now been extended to include new results on $v_3-v_n$ (n=2-5) correlations. Several unique features in these correlations suggest new sources of geometrical fluctuations in the initial state. To better constrain the initial condition, measurements of the longitudinal multiplicity correlation are also presented.