Measurement of jet suppression in central Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

Submission Date: 
05/02/2015
Article Information
Submission Form
System: 
Pb-Pb
Energy: 
2.76 TeV
Abstract Plain Text: 

The transverse momentum (pT) spectrum and nuclear modification factor (RAA) of reconstructed jets in 0–10% and 10–30% central Pb–Pb collisions at sNN = 2.76 TeV were measured. Jets were reconstructed from charged and neutral particles, utilizing the ALICE

tracking detectors and Electromagnetic Calorimeter (EMCal), with the anti-kT jet algorithm for a resolution parameter R = 0.2. The jet pT spectra are reported in the pseudo-rapidity interval of |ηjet| < 0.5 for 40 < pT,jet < 120 GeV/c in 0–10% and for 30 < pT,jet < 100 GeV/in 10–30% collisions. Reconstructed jets were required to contain a leading charged particle with pT > 5 GeV/c to suppress jets constructed from mainly combinatorial background in Pb–Pb collisions. In pp collisions at s = 2.76 TeV, the leading charged particle requirement only has a small effect for measured jets with pT,jet > 40 GeV/c. The nuclear modification factor, obtained by dividing the jet spectrum measured in Pb–Pb with that in pp collisions scaled the number of independent nucleon–nucleon collisions estimated in a Glauber model is found to be 0.28 ± 0.07 in 0–10% and 0.36 ± 0.08 in 10–30% collisions, almost independent of pT,jet within the uncertainties of the measurement. The observed suppression is in agreement with expectations from two different model calculations.