Measurement of the azimuthal anisotropy of charged particles produced in √sNN = 5.02 TeV Pb+Pb collisions with the ATLAS detector

Measurements of the azimuthal anisotropy in lead–lead collisions at $$\sqrt{s_{_\text {NN}}}$$ = 5.02 TeV are presented using a data sample corresponding to 0.49 $${\mathrm {nb}}^{-1}$$ integrated luminosity collected by the ATLAS experiment at the LHC in 2015. The recorded minimum-bias sample is enhanced by triggers for “ultra-central” collisions, providing an opportunity to perform detailed study of flow harmonics in the regime where the initial state is dominated by fluctuations. The anisotropy of the charged-particle azimuthal angle distributions is characterized by the Fourier coefficients, $$v_{2}$$ – $$v_{7}$$ , which are measured using the two-particle correlation, scalar-product and event-plane methods. The goal of the paper is to provide measurements of the differential as well as integrated flow harmonics $$v_{n}$$ over wide ranges of the transverse momentum, 0.5  $$<$$  60 GeV, the pseudorapidity, $$|\eta |<$$  2.5, and the collision centrality 0–80%. Results from different methods are compared and discussed in the context of previous and recent measurements in Pb+Pb collisions at $$\sqrt{s_{_\text {NN}}}$$ = 2.76  $$\mathrm{TeV}$$ and 5.02  $$\mathrm{TeV}$$ . In particular, the shape of the $$p_{\mathrm{T}}$$ dependence of elliptic or triangular flow harmonics is observed to be very similar at different centralities after scaling the $$v_{n}$$ and $$p_{\mathrm{T}}$$ values by constant factors over the centrality interval 0–60% and the $$p_{\mathrm{T}}$$ range 0.5  $$< p_{\mathrm{T}}<$$  5 GeV.