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Anisotropic flow of charged particles in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV

The ALICE collaboration Adam, Jaroslav ; Adamova, Dagmar ; Aggarwal, Madan Mohan ; et al.
Phys.Rev.Lett. 116 (2016) 132302, 2016.
Inspire Record 1419244 DOI 10.17182/hepdata.72886

We report the first results of elliptic ($v_2$), triangular ($v_3$) and quadrangular flow ($v_4$) of charged particles in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV with the ALICE detector at the CERN Large Hadron Collider. The measurements are performed in the central pseudorapidity region $|\eta|<0.8$ and for the transverse momentum range $0.2<p_{\rm T}<5$ GeV/$c$. The anisotropic flow is measured using two-particle correlations with a pseudorapidity gap greater than one unit and with the multi-particle cumulant method. Compared to results from Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV, the anisotropic flow coefficients $v_{2}$, $v_{3}$ and $v_{4}$ are found to increase by ($3.0\pm0.6$)%, ($4.3\pm1.4$)% and ($10.2\pm3.8$)%, respectively, in the centrality range 0-50%. This increase can be attributed mostly to an increase of the average transverse momentum between the two energies. The measurements are found to be compatible with hydrodynamic model calculations. This comparison provides a unique opportunity to test the validity of the hydrodynamic picture and the power to further discriminate between various possibilities for the temperature dependence of shear viscosity to entropy density ratio of the produced matter in heavy-ion collisions at the highest energies.

22 data tables

Centrality dependence of $v_2$, with two- and multi-particle correlations, integrated over the $p_{\rm T}$ range 0.2 < $p_{\rm T}$ < 5.0 GeV/$c$, at $\sqrt{s_{\rm NN}}$ = 5.02 TeV.

Centrality dependence of $v_2$, with two- and multi-particle correlations, integrated over the $p_{\rm T}$ range 0.2 < $p_{\rm T}$ < 5.0 GeV/$c$, at $\sqrt{s_{\rm NN}}$ = 5.02 TeV.

Centrality dependence of $v_3$ and $v_4$, with two-particle correlations, integrated over the $p_{\rm T}$ range 0.2 < $p_{\rm T}$ < 5.0 GeV/c, at $\sqrt{s_{\rm NN}}$ = 5.02 TeV.

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Forward-central two-particle correlations in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration Adam, Jaroslav ; Adamova, Dagmar ; Aggarwal, Madan Mohan ; et al.
Phys.Lett.B 753 (2016) 126-139, 2016.
Inspire Record 1379977 DOI 10.17182/hepdata.70826

Two-particle angular correlations between trigger particles in the forward pseudorapidity range ($2.5 < |\eta| < 4.0$) and associated particles in the central range ($|\eta| < 1.0$) are measured with the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The trigger particles are reconstructed using the muon spectrometer, and the associated particles by the central barrel tracking detectors. In high-multiplicity events, the double-ridge structure, previously discovered in two-particle angular correlations at midrapidity, is found to persist to the pseudorapidity ranges studied in this Letter. The second-order Fourier coefficients for muons in high-multiplicity events are extracted after jet-like correlations from low-multiplicity events have been subtracted. The coefficients are found to have a similar transverse momentum ($p_{\rm T}$) dependence in p-going (p-Pb) and Pb-going (Pb-p) configurations, with the Pb-going coefficients larger by about $16\pm6$%, rather independent of $p_{\rm T}$ within the uncertainties of the measurement. The data are compared with calculations using the AMPT model, which predicts a different $p_{\rm T}$ and $\eta$ dependence than observed in the data. The results are sensitive to the parent particle $v_2$ and composition of reconstructed muon tracks, where the contribution from heavy flavour decays are expected to dominate at $p_{\rm T}>2$ GeV/$c$.

4 data tables

$v_{2}^{\mu}\{\rm{2PC,sub}\}$ extracted from muon-track correlations.

$v_{2}^{\mu}\{\rm{2PC,sub}\}$ coefficients from muon-tracklet correlations in p-going direction.

$v_{2}^{\mu}\{\rm{2PC,sub}\}$ coefficients from muon-tracklet correlations in Pb-going direction.

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Measurement with the ATLAS detector of multi-particle azimuthal correlations in p+Pb collisions at $\sqrt{s_{NN}}$ =5.02 TeV

The ATLAS collaboration Aad, Georges ; Abajyan, Tatevik ; Abbott, Brad ; et al.
Phys.Lett.B 725 (2013) 60-78, 2013.
Inspire Record 1223123 DOI 10.17182/hepdata.66179

In order to study further the long-range correlations ("ridge") observed recently in p+Pb collisions at sqrt(s_NN) =5.02 TeV, the second-order azimuthal anisotropy parameter of charged particles, v_2, has been measured with the cumulant method using the ATLAS detector at the LHC. In a data sample corresponding to an integrated luminosity of approximately 1 microb^(-1), the parameter v_2 has been obtained using two- and four-particle cumulants over the pseudorapidity range |eta|<2.5. The results are presented as a function of transverse momentum and the event activity, defined in terms of the transverse energy summed over 3.1<eta<4.9 in the direction of the Pb beam. They show features characteristic of collective anisotropic flow, similar to that observed in Pb+Pb collisions. A comparison is made to results obtained using two-particle correlation methods, and to predictions from hydrodynamic models of p+Pb collisions. Despite the small transverse spatial extent of the p+Pb collision system, the large magnitude of v_2 and its similarity to hydrodynamic predictions provide additional evidence for the importance of final-state effects in p+Pb reactions.

10 data tables

The second flow harmonic measured with the two-particle cumulants as a function of transverse momentum in the event activity bin of 25-40 GeV.

The second flow harmonic measured with the two-particle cumulants as a function of transverse momentum in the event activity bin of 40-55 GeV.

The second flow harmonic measured with the two-particle cumulants as a function of transverse momentum in the event activity bin of 55-80 GeV.

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