Elliptic flow of identified hadrons in small collisional systems measured with ALICE

Abstract

Recent observations of long-range multi-particle azimuthal correlations in p--Pb and high multiplicity pp collisions provided new insights into collision dynamics and opened a possibility to study collective effects in these small systems. New measurement of $p_{\mathrm{T}}$-differential elliptic flow ($v_2$) coefficient for inclusive charged hadrons as well as a variety of identified particle species in p--Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV recorded by ALICE during the LHC Run 2 data taking are presented. Besides high precision measurements of $v_2(p_{\mathrm{T}})$ for ${\pi }^{\pm },{\mathrm{K}}^{\pm }$ and $\mathrm{p}(\bar{\mathrm{p}})$, the very first results for ${\mathrm{K}}_{\mathrm{S}}^0,\mathrm{\Lambda }(\bar{\mathrm{\Lambda }})$ and $\varphi$ are shown. In order to eliminate non-flow contamination, a pseudorapidity separation between correlated particles is applied as well as subtraction of remaining non-flow estimate based on a measurement of minimum-bias pp collisions at $\sqrt{s}=13$ TeV. Moreover, reported characteristic mass ordering and approximate NCQ and $\mathrm{K}{\mathrm{E}}_{\mathrm{T}}$ scaling of $v_2$ allows to test various theoretical models, constrain the initial conditions, and probe the origin of collective behavior in small collision systems.

arXiv comment4 pages, 2 figures, conference proceedings, submitted to Null. Phys. A

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