Elliptic flow of identified hadrons in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV

Abstract

The elliptic flow coefficient ($v_2$) of identified particles in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV was measured with the ALICE detector at the LHC. The results were obtained with the Scalar Product method, a two-particle correlation technique, using a pseudo-rapidity gap of $|\Delta \eta |>0.9$ between the identified hadron under study and the reference particles. The $v_2$ is reported for ${\pi }^{\pm }$, ${\mathrm{K}}^{\pm }$, ${\mathrm{K}}_{\mathrm{S}}^0$, p+$\overline{\mathrm{p}}$, $\varphi$, $\Lambda$+$\overline{\mathrm{\Lambda }}$, ${\Xi }^{-}$+${\overline{\Xi }}^{+}$ and ${\Omega }^{-}$+${\overline{\Omega }}^{+}$ in several collision centralities. In the low transverse momentum ($p_{\mathrm{T}}$) region, $p_{\mathrm{T}}<2$GeV/$c$, $v_2(p_{\mathrm{T}})$ exhibits a particle mass dependence consistent with elliptic flow accompanied by the transverse radial expansion of the system with a common velocity field. The experimental data for ${\pi }^{\pm }$ and $\mathrm{K}$ are described fairly well by hydrodynamical calculations coupled to a hadronic cascade model (VISHNU) for central collisions. However, the same calculations fail to reproduce the $v_2(p_{\mathrm{T}})$ for p+$\overline{\mathrm{p}}$, $\varphi$, $\Lambda$+$\overline{\mathrm{\Lambda }}$ and ${\Xi }^{-}$+${\overline{\Xi }}^{+}$. For transverse momentum values larger than about 3 GeV/$c$, particles tend to group according to their type, i.e. mesons and baryons. However, the experimental data at the LHC exhibit deviations from the number of constituent quark (NCQ) scaling at the level of $\pm$20$\%$ for $p_{\mathrm{T}}>3$GeV/$c$.

80 pages, 13 captioned figures in text and 50 in appendix A, 7 tables, authors from page 74, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/1742

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Cited by in corpus (5)

• Long-range two-particle correlations of strange hadrons with charged particles in pPb and PbPb collisions at LHC energies
• Measuring and interpreting charge dependent anisotropic flow
• Long-range angular correlations at the LHC with ALICE
• Hadronic observables from a hadronic rescattering model in $Pb+Pb$ collisions at $\sqrt{s_{NN}}=2.76$ TeV
• Collective phenomena in high-energy nuclear collisions