In-Medium Energy Loss and Correlations in Pb-Pb Collisions at sqrt(s_NN) = 2.76 TeV

TL;DR

This paper reports on measurements of in-medium energy loss and particle correlations in Pb-Pb collisions at 2.76 TeV, providing insights into quark-gluon plasma properties at unprecedented energies.

Contribution

It presents new experimental results on particle suppression and correlations at LHC energies, extending understanding of quark-gluon plasma effects beyond previous RHIC findings.

Findings

Observation of particle suppression (R_AA) at high pT

Detection of away-side jet suppression (I_AA)

Evidence of collective effects like the ridge at low pT

Abstract

ALICE (A Large Ion Collider Experiment) is the dedicated heavy-ion experiment at the LHC. In fall 2010, Pb-Pb collisions were recorded at a center-of-mass energy of 2.76 TeV per nucleon pair, about 14 times higher than the energy achieved in A-A collisions at RHIC. The study of the produced hot and dense matter with an unprecedented energy density allows the characterization of the quark-gluon plasma, the deconfined state of quarks and gluons, predicted by QCD. The study of in-medium partonic energy loss allows insights into the density of the medium and the energy-loss mechanisms. This paper presents results based on inclusive spectra as well as two and more-particle correlations of charged particles. These are well suited to assess in-medium effects, ranging from the suppression of particles (R_AA) and away-side jets (I_AA) at high pT to long-range phenomena attributed to collective effects like the ridge at low pT. The analysis is discussed and the results are presented in the context of earlier RHIC measurements where appropriate.