Figure 83

Associated yield per trigger particle in $\Delta \varphi$ and $\Delta \eta$ for pairs of charged particles with $2 p_{\rm T,trig} 4$ GeV/{\it c} and $1 p_{\rm T,assoc} 2$ GeV/{\it c} in p--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV for the 0--20\% multiplicity class, after subtraction of the associated yield obtained in the 60--100\% event class under the assumption that the latter multiplicity class is completely dominated by non-flow correlations . A clear double-ridge signal spanning a large range in $\Delta\eta$ can be seen on the near-side $|\Delta\varphi| \approx 0$ and on the away-side $|\Delta\varphi| \approx \pi$, indicative of the possibility of a collective behaviour in p--Pb collisions.