Collective flow in p-Pb and d-Pb collisions at TeV energies

TL;DR

The paper investigates whether small systems created in p-Pb and d-Pb collisions at TeV energies can form a dense, collectively expanding medium. Using event-by-event 3+1D viscous hydrodynamics with Glauber Monte Carlo initial conditions and a lattice-informed equation of state, they predict particle spectra and azimuthal flow coefficients. They find nonzero elliptic and triangular flow: v2 about 3-4% in p-Pb and up to ~10% in central d-Pb, with initial eccentricities seed these flows. The results suggest measurable collective effects in small systems and provide a framework for comparing to future LHC measurements and informing heavy-ion phenomenology.

Abstract

We apply the hydrodynamic model for the dynamics of matter created in p-Pb collisions at 4.4TeV and d-Pb collisions at 3.11TeV. The fluctuating initial conditions are calculated in the Glauber Monte-Carlo model for several centrality classes. The expansion is performed event by event in 3+1-dimensional viscous hydrodynamics. Noticeable elliptic and triangular flows appear in the distributions of produced particles.

Figures (20)

• Figure 1: (Color online) The distribution of participant nucleons at different impact parameters (boxes) and the average number of nucleons as function of the impact parameter (solid line) for p-Pb interactions.
• Figure 2: (Color online) The probability distribution of participant nucleons in p-Pb interactions. The three centrality classes considered in the simulations are defined by cuts in the number of participant nucleons.
• Figure 3: (Color online) Same as Fig. \ref{['fig:nwpprob']} but for d-Pb interactions.
• Figure 4: (Color online) Eccentricity (solid line) and triangularity (dashed line) in p-Pb interactions as function of the number of participant nucleons.
• Figure 5: (Color online) Same as Fig. \ref{['fig:e2pPb']} but for d-Pb interactions.