Measurements of azimuthal anisotropies at forward and backward rapidity with muons in high-multiplicity p-Pb collisions at √sNN=8.16 TeV

The study of the azimuthal anisotropy of inclusive muons produced in p-Pb collisions at root sNN = 8.16 TeV, using the ALICE detector at the LHC is reported. The measurement of the second-order Fourier coefficient of the particle azimuthal distribution, v2, is performed as a function of transverse momentum pT in the 0-20% high-multiplicity interval at both forward (2.03 < yCMS < 3.53) and backward (-4.46 < yCMS < -2.96) rapidities over a wide pT range, 0.5 < pT 10 GeV/c, in which a dominant contribution of muons from heavy-flavour hadron decays is expected at pT 2 GeV/c. The v2 coefficient of inclusive muons is extracted using two different techniques, namely two-particle cumulants, used for the first time for heavy-flavour measurements, and forward-central two-particle correlations. Both techniques give compatible results. A positive v2 is measured at both forward and backward rapidities with a significance larger than 4.7 and 7.6 sigma, respectively, in the interval 2 < pT < 6 GeV/c. Comparisons with previous measurements in p-Pb collisions at root sNN = 5.02 TeV, and with AMPT and CGC-based theoretical calculations are discussed. The findings impose new constraints on the theoretical interpretations of the origin of the collective behaviour in small collision systems. (c) 2023 European Organization for Nuclear Research. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.

Automated summary

This study reports the investigation of azimuthal anisotropy of inclusive muons produced in p-Pb collisions at root sNN = 8.16 TeV using the ALICE detector at the LHC. The measurement of the second-order Fourier coefficient, v2, is performed as a function of transverse momentum pT in different rapidity ranges. The results show a positive v2 at both forward and backward rapidities in a specific pT interval, which imposes new constraints on the theoretical interpretations of collective behavior in small collision systems.