Is hadronic flow produced in p--Pb collisions at the Large Hadron Collider?

TL;DR

This study uses the UrQMD model to analyze azimuthal correlations in p--Pb collisions at 5.02 TeV, finding that the system does not produce collective flow but shows mass-ordering effects due to hadronic interactions.

Contribution

It demonstrates that the observed mass-ordering in p--Pb collisions can arise from hadronic interactions without collective flow, challenging assumptions about flow signatures.

Findings

UrQMD simulations show no collective flow in p--Pb collisions.

Mass-ordering of $v_2(p_T)$ is due to hadronic interactions, not fluid expansion.

p--Pb system behaves mainly as a non-flow dominant system.

Abstract

Using the Ultra-relativistic Quantum Molecular Dynamics ({\tt UrQMD}) model, we investigate the azimuthal correlations in p--Pb collisions at $\sqrt{s_{_{\rm NN}}}=5.02$ TeV. It is shown that the simulated hadronic p--Pb system can not generate the collective flow signatures, but mainly behaves as a non-flow dominant system. However, the characteristic $v_{2}(p_{\rm T})$ mass-ordering of pions, kaons and protons is observed in {\tt UrQMD} simulations, which is the consequence of hadronic interactions and not necessarily associated with strong fluid-like expansions.