## Higher harmonic flow coefficients of identified hadrons in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

##### Type

Journal article###### Peer reviewed

###### publishedVersion

##### View/Open

##### Date

2016-09##### Author

##### Metadata

Show full item record##### Abstract

The elliptic, triangular, quadrangular and pentagonal anisotropic flow coefficients for $\pi^{\pm}$, $\mathrm{K}^{\pm}$ and p+$\overline{\mathrm{p}}$ in Pb-Pb collisions at $\sqrt{s_\mathrm{{NN}}} = 2.76$ TeV were measured with the ALICE detector at the Large Hadron Collider. The results were obtained with the Scalar Product method, correlating the identified hadrons with reference particles from a different pseudorapidity region. Effects not related to the common event symmetry planes (non-flow) were estimated using correlations in pp collisions and were subtracted from the measurement. The obtained flow coefficients exhibit a clear mass ordering for transverse momentum ($p_{\mathrm{T}}$) values below $\approx$ 3 GeV/$c$. In the intermediate $p_{\mathrm{T}}$ region ($3 < p_{\mathrm{T}} < 6$ GeV/$c$), particles group at an approximate level according to the number of constituent quarks, suggesting that coalescence might be the relevant particle production mechanism in this region. The results for $p_{\mathrm{T}} < 3$ GeV/$c$ are described fairly well by a hydrodynamical model (iEBE-VISHNU) that uses initial conditions generated by A Multi-Phase Transport model (AMPT) and describes the expansion of the fireball using a value of 0.08 for the ratio of shear viscosity to entropy density ($\eta/s$), coupled to a hadronic cascade model (UrQMD). Finally, expectations from AMPT alone fail to quantitatively describe the measurements for all harmonics throughout the measured transverse momentum region. However, the comparison to the AMPT model highlights the importance of the late hadronic rescattering stage to the development of the observed mass ordering at low values of $p_{\mathrm{T}}$ and of coalescence as a particle production mechanism for the particle type grouping at intermediate values of $p_{\mathrm{T}}$ for all harmonics.

##### Citation

Adam J, Adamová D, Aggarwal MM, Aglieri Rinella G, Agnello M, Agrawal N, Ahammed Z, Ahmad SF, Ahn SU, Aiola S, Alme J, Helstrup H, Hetland KF, Kileng B, Altinpinar S, Djuvsland Ø, Lønne P, Nystrand J, Rehman Au, Røhrich D, Tambave GJ, Ullaland K, Velure A, Wagner B, Zhang H, Zhou Z, Zhu H, Arsene IC, Bätzing P, Dordic O, Lindal S, Mahmood SM, Milosevic J, Qvigstad H, Richter M, Røed K, Skaali TB, Tveter TS, Wikne JC, Zhao C, Langøy R, Lien JA, Akindinov A, Alam SN, De Albuquerque DS, Aleksandrov D, Alessandro B, Alexandre D, Alfaro Molina JR, Alici A, ALICE C. Higher harmonic flow coefficients of identified hadrons in Pb-Pb collisions at √sNN=2.76 TeV. Journal of High Energy Physics (JHEP). 2016;2016:164##### Publisher

Springer##### Subject

Hadron-Hadron scattering##### Collections

Copyright CERN, for the benefit of the ALICE Collaboration