Transverse momentum and process dependent azimuthal anisotropies in ${\sqrt{s}}_{NN}$=8.16 TeV p+Pb collisions with the ATLAS detector

The azimuthal anisotropy of charged particles produced in ${\sqrt{s}}_{NN}$=8.16 TeV p+Pb collisions is measured with the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 165 nb${}^{-1}$ that was collected in 2016. Azimuthal anisotropy coefficients, elliptic $v_2$ and triangular $v_3$, extracted using two-particle correlations with a non-flow template fit procedure, are presented as a function of particle transverse momentum (p${}_T$) between 0.5 and 50 GeV. The $v_2$ results are also reported as a function of centrality in three different particle p${}_T$ intervals. The results are reported from minimum-bias events and jet-triggered events, where two jet p${}_T$ thresholds are used. The anisotropies for particles with p${}_T$ less than about 2 GeV are consistent with hydrodynamic flow expectations, while the significant non-zero anisotropies for p${}_T$ in the range 9–50 GeV are not explained within current theoretical frameworks. In the p${}_T$ range 2–9 GeV, the anisotropies are larger in minimum-bias than in jet-triggered events. Possible origins of these effects, such as the changing admixture of particles from hard scattering and the underlying event, are discussed.