Suppression of high $p_{T}$ hadrons in $Pb+Pb$ Collisions at LHC

TL;DR

This paper predicts the suppression of high transverse momentum hadrons in lead-lead collisions at LHC using a perturbative QCD model with jet quenching effects calibrated by RHIC data, incorporating hydrodynamics for bulk matter evolution.

Contribution

It introduces a predictive framework combining NLO pQCD with medium-modified fragmentation functions and hydrodynamics, calibrated by RHIC and LHC data, to analyze high-$p_{T}$ hadron suppression at LHC.

Findings

Predicted nuclear modification factor $R_{AA}$ for high-$p_{T}$ pions at LHC.

Quantified the effect of jet quenching on hadron spectra.

Constrained initial parton density using ALICE charged hadron multiplicity data.

Abstract

Nuclear modification factor $R_{AA}(p_{T})$ for large transverse momentum pion spectra in $Pb+Pb$ collisions at $\sqrt{s}=2.76$ TeV is predicted within the NLO perturbative QCD parton model. Effect of jet quenching is incorporated through medium modified fragmentation functions within the higher-twist approach. The jet transport parameter that controls medium modification is proportional to the initial parton density and the coefficient is fixed by the RHIC data on suppression of large $p_{T}$ hadron spectra. Data on charged hadron multiplicity $dN_{ch}/d\eta=1584 \pm 80$ in central $Pb+Pb$ collisions from the ALICE Experiment at the LHC are used to constrain the initial parton density both for determining the jet transport parameter and the 3+1D ideal hydrodynamic evolution of the bulk matter that is employed for the calculation of $R_{PbPb}(p_{T})$ for neutral pions.