Speaker
Description
Measurements of the azimuthal anisotropy of charged particles in heavy-ion collisions are sensitive to the detailed properties of the quark-gluon plasma, in particular its dependence on initial conditions, transport coefficients and time evolution. The presented measurements are based on 0.49 n$\mathrm{b}^{-1}$ of Pb+Pb data collected by the ATLAS detector in 2015 with center-of-mass energy $\sqrt{s_{NN}}=5.02$ TeV. The elliptic flow and higher-order Fourier coefficients ($v_{2}$ - $v_{7}$) are presented in a wide range of transverse momenta ($p_\mathrm{T}<60$ GeV), pseudorapidity ($|\eta|<2.5$) and 0-80% collision centrality. The collected minimum-bias sample is enhanced by triggers for "ultra-central" collisions, providing an opportunity to perform precise measurements of flow harmonics in the fluctuation-dominated regime. The magnitude of azimuthal anisotropy is estimated by measuring the angular correlations of produced particles using both the scalar product and event plane methods. To suppress non-flow, $v_{n}$ harmonics are calculated by correlating two flow vectors estimated in two different detectors separated in pseudorapidity (the forward calorimeter $3.2<|\eta|<4.8$, or the inner detector $|\eta|<2.5$), and in the opposite hemispheres. The obtained results are compared to the $v_{n}(p_\mathrm{T})$ values at measured in $\sqrt{s_{NN}}=2.76$ TeV Pb+Pb collisions and recent $\sqrt{s_{NN}}=5.44$ TeV Xe+Xe collisions as well as to predictions of hydrodynamical models.
| Content type | Experiment |
|---|---|
| Collaboration | ATLAS |
| Centralised submission by Collaboration | Presenter name already specified |
