Neutral meson production in pp, p–Pb and Pb–Pb collisions with ALICE at the LHC

Abstract

The ALICE experiment is mainly devoted to the study of QGP expected to be created in heavy-ion collisions at the LHC. In the early stage of such collisions, partons can be scattered and photons can be produced in energetic hard processes. High energy partons will interact with the QGP, and from the measurement of the particles originated from the parton fragmentation in vacuum, one can infer transport properties of the QGP. Therefore, study of high-pT hadrons production is important to constrain the properties of the hot and dense medium. The strong suppression of the high-pT hadrons in heavy-ion collisions has been explained by the energy loss of the partons in medium and it can be investigated experimentally via the nuclear modification factor of hadrons.ALICE measured neutral mesons (π0 and η) at mid-rapidity in a wide pT range in pp, p-Pb and Pb-Pb collisions. Neutral mesons are reconstructed via complementary methods, using the electromagnetic calorimeters, PHOS and EMCal, and by the central tracking system, identifying photons converted to e+e− pairs in the material of the inner barrel detectors (ITS and TPC). Measurement of neutral meson spectra in pp collisions at s=0.9,2.76,7 and 8 TeV provides valuable comparison data for pQCD calculations and allows to study scaling properties of hadron production at the LHC energies. The study of neutral mesons production in p-Pb collisions helps to disentangle initial and final state effects on the suppression itself. The latest results of neutral meson measurement in pp, p-Pb and Pb-Pb collisions will be shown in this paper.