Neutral pion and η meson production at midrapidity in Pb-Pb collisions at √sNN = 2.76 TeV

Abstract

Neutral pion and η meson production in the transverse momentum range 1 < p T < 20 GeV / c have been measured at midrapidity by the ALICE experiment at the Large Hadron Collider (LHC) in central and semicentral Pb-Pb collisions at √ s NN = 2.76 TeV. These results were obtained using the photon conversion method as well as the Photon Spectrometer (PHOS) and Electromagnetic Calorimeter detectors. The results extend the upper p T reach of the previous ALICE π 0 measurements from 12 to 20 GeV / c and present the first measurement of η meson production in heavy-ion collisions at the LHC. The η / π 0 ratio is similar for the two centralities and reaches at high p T a plateau value of 0.457 ±

0 . 013 stat

±

0 . 018 syst . A suppression of similar magnitude for π 0 and η meson production is observed in Pb-Pb collisions with respect to their production in p p collisions scaled by the number of binary nucleon-nucleon collisions. We discuss the results in terms of Next to Leading Order (NLO) pQCD predictions and hydrodynamic models. The measurements show a stronger suppression than observed at lower center-of-mass energies in the p T range 6 < p T < 10 GeV / c . For p T < 3 GeV / c , hadronization models describe the π 0 results while for the η some tension is observed.