Measurement of jet pT spectra in Pb–Pb collisions at = 2.76 TeV with the ALICE detector at the LHC

Salvatore Aiola

doi:10.1088/1742-6596/446/1/012005

Abstract

Reconstruction of jets in high-energy heavy-ion collisions is challenging due to the large and fluctuating background coming from the underlying event. We report results on full jet reconstruction, obtained from data collected in 2011 by the ALICE detector at LHC for Pb-Pb collisions at = 2.76 TeV. The analysis makes use of the tracking system and the electromagnetic calorimeter. Signal jets, which come from hard scattered partons, are reconstructed using the anti-kT jet finder algorithm. The average background is subtracted on a jet-by-jet basis to reduce the contribution to the jet reconstructed energy coming from the underlying event. The jet spectrum is corrected to account for fluctuations in the background momentum density and detector effects through unfolding.

Highlights

QCD jets are produced in high-energy particle collisions as a result of the fragmentation of a high momentum scattered parton
The measured values of the observable, the jet pT, are subject to random fluctuations, due to regionto-region differences in the background momentum density and to the detector response. This means that each observation is characterized by a true value ptTr,ujeet, and by a measured value pmT,ejaets
We have reported on√the analysis techniques utilized to reconstruct jets in the 10% most central Pb–Pb collisions at sNN = 2.76 TeV recorded by ALICE in 2011

Summary

Introduction

QCD jets are produced in high-energy particle collisions as a result of the fragmentation of a high momentum scattered parton They are reconstructed using a welldefined algorithm, which acts as a working definition of a jet, to be used consistently in phenomenological models. The measured values of the observable, the jet pT, are subject to random fluctuations, due to regionto-region differences in the background momentum density and to the detector response. This means that each observation is characterized by a true (and unknown) value ptTr,ujeet, and by a measured value pmT,ejaets. The generator-level and detector-level jets are matched following a geometrical criterion

Results

Nevt Ncoll

Conclusions