Geometrical scaling for energies available at the BNL Relativistic Heavy Ion Collider to those at the CERN Large Hadron Collider

TL;DR

This paper investigates how the average transverse momentum of identified hadrons scales with energy and system size from RHIC to LHC, revealing universal patterns and deviations at high energies.

Contribution

It extends geometrical scaling analysis to include LHC energies and compares different collision systems, highlighting system size independence and energy-dependent deviations.

Findings

Average p_T dependence on energy decreases from BES to LHC.

At LHC energies, a deviation from linearity in central collisions is observed.

Scaling behaviors are consistent across different collision systems and energies.

Abstract

Based on the recent RHIC and LHC experimental results, the $\langle p_T\rangle$ dependence of identified light flavour charged hadrons on $\sqrt{(\frac{dN}{dy})/S_{\perp}}$, relevant scale in gluon saturation picture, is studied from $\sqrt{s_{NN}}$=7.7 GeV up to 5.02 TeV. This study is extended to the slopes of the $\langle p_T\rangle$ dependence on the particle mass and the $\langle\beta_T\rangle$ parameter from Boltzmann-Gibbs Blast Wave (BGBW) fits of the $p_T$ spectra. A systematic decrease of the slope of the $\langle p_T\rangle$ dependence on $\sqrt{(\frac{dN}{dy})/S_{\perp}}$ from BES to the LHC energies is evidenced. While for the RHIC energies, within the experimental errors, the $\langle p_T\rangle$/$\sqrt{(\frac{dN}{dy})/S_{\perp}}$ does not depend on centrality, at the LHC energies a deviation from a linear behaviour is observed towards the most central collisions. The influence of the corona contribution to the observed trends is discussed. The slopes of the $\langle p_T\rangle$ particle mass dependence and the $\langle\beta_T\rangle$ parameter from BGBW fits scale well with $\sqrt{(\frac{dN}{dy})/S_{\perp}}$. Similar systematic trends for pp at $\sqrt{s}$=7 TeV are in a good agreement with the ones corresponding to Pb-Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV and 5.02 TeV pointing to a system size independent behaviour.