Predictions for 5.023 TeV Pb+Pb collisions at the LHC

TL;DR

This paper predicts bulk observables for 5.023 TeV Pb+Pb collisions at the LHC using a combined NLO pQCD, saturation, and viscous hydrodynamics model, extending previous energy predictions and analyzing their centrality dependence.

Contribution

It provides new predictions for bulk observables at 5.023 TeV Pb+Pb collisions using the EKRT model, including multiplicity and flow coefficients, with implications for QCD matter viscosity.

Findings

Predicted charged hadron multiplicity in 0-5 ext{ }ackslash%} centrality: 1876-2046.

Flow coefficients and correlations similar to 2.76 TeV results.

Power-law increase of multiplicity with collision energy, exponent ~0.17.

Abstract

We compute predictions for various low-transverse-momentum bulk observables in $\sqrt{s_{NN}} = 5.023$ TeV Pb+Pb collisions at the LHC from the event-by-event next-to-leading-order perturbative-QCD + saturation + viscous hydrodynamics ("EKRT") model. In particular, we consider the centrality dependence of charged hadron multiplicity, flow coefficients of the azimuth-angle asymmetries and correlations of event-plane angles. The centrality dependencies of the studied observables are predicted to be very similar to those at 2.76 TeV, and the magnitudes of the flow coefficients and event-plane angle correlations are predicted to be close to those at 2.76 TeV. The flow coefficients may, however, offer slightly more discriminating power on the temperature dependence of QCD matter viscosity than the 2.76 TeV measurements. Our prediction for the multiplicity in the 0-5\% centrality class, obtained using the two temperature-dependent shear-viscosity-to-entropy ratios that give the best overall fit to RHIC and LHC data is $dN_{\rm ch}/d\eta\big|_{|\eta|\le 0.5} =1876\dots2046$. We also predict a power-law increase from 200 GeV Au+Au collisions at RHIC to 2.76 and 5.023 TeV Pb+Pb collisions at the LHC, $dN_{\rm ch}/d\eta\big|_{|\eta|\le 0.5} \propto s^{0.164\dots0.174}$.