Study of collective anisotropies $v_2$ and $v_3$ and their fluctuations in $pA$ collisions at LHC within a relativistic transport approach

Abstract

We have developed a relativistic transport approach at fixed $\eta /s(T)$ that incorporates initial space fluctuations generated by wounded quark model to study the hadron observables in 5.02 TeV p+Pb collisions. We find that our approach is able to correctly predict quite well several existing experimental measurements assuming a matter with $\eta /s=1/4\pi$, a result similar to previous studies within a viscous hydrodynamics approach. Besides, we further discuss the sensitivity of the results on both $\eta /s(T)$ and the smearing width. Our transport approach has the possibility to include in initial conditions the power law tail associated to minijet, and this improvement extends the agreement with the experimental data to higher $p_T$ ranges. We also perform a comparison to Pb+Pb collisions pointing out that even if the collective flows have a similar magnitude the features of the matter created are different. By studying the correlation between collective flows and initial geometry, we find that the correlation decreases faster in small systems with the increase of $n$ and centrality. In particular we show that the variance of ${\sigma }_{v_n}/⟨v_n⟩$ has a quite different evolution with centrality for p+Pb, so their measurement could provide some further hint about the correctness of current modelling.

Comments: 10 pages, 15 figures