Measurement of Fourier harmonics associated with the long-range correlations in ${\mbox{$p$+Pb}}$ collisions at ${\mbox{$\sqrt{s_{\mathrm{NN}}}$}}$ = 5.02 TeV with the ATLAS detector.

Measurements of the first five azimuthal harmonics, $v_1$ to $v_5$, are presented, using 28 ${\mbox{${\rm nb}^{-1}$}}$ of $p$+Pb collisions at ${\mbox{$\sqrt{s_{\mathrm{NN}}}$}}$ = 5.02 TeV measured with the ATLAS detector at the LHC. The results are presented as a function of transverse momentum (${\mbox{$p_{\mathrm{T}}$}}$) in the range 0.4 $< {\mbox{$p_{\mathrm{T}}$}} <$ 12 GeV and in different intervals of event activity defined by the number of reconstructed tracks. The extracted $v_n$ values for $n$ = 2 to 5 decrease with $n$. The $v_2$ and $v_3$ values are found to be positive in the measured ${\mbox{$p_{\mathrm{T}}$}}$ range. The $v_1$ is also measured as a function of ${\mbox{$p_{\mathrm{T}}$}}$ and is observed to change sign around ${\mbox{$p_{\mathrm{T}}$}} \approx$ 1.5$-$2.0 GeV and then increase to about 0.1 for ${\mbox{$p_{\mathrm{T}}$}} >$ 4 GeV. The $v_2$(${\mbox{$p_{\mathrm{T}}$}}$), $v_3$(${\mbox{$p_{\mathrm{T}}$}}$) and $v_4$(${\mbox{$p_{\mathrm{T}}$}}$) are compared to the $v_n$ coefficients in Pb+Pb collisions at ${\mbox{$\sqrt{s_{\mathrm{NN}}}$}}$ = 2.76 TeV with similar event multiplicities. Reasonable agreement is observed after accounting for the difference in the average ${\mbox{$p_{\mathrm{T}}$}}$ of particles produced in the two collision systems.