Direct photon and neutral pion production in pp and Pb-Pb collisions measured with the ALICE experiment at LHC

TL;DR

This paper presents measurements of direct photon and neutral pion production in pp and Pb-Pb collisions at the LHC, providing insights into the properties of the hot QCD medium and serving as references for heavy-ion collision analysis.

Contribution

It reports new experimental results from ALICE on photon and pion production, enhancing understanding of QCD medium properties and parton energy loss mechanisms.

Findings

Neutral pion suppression indicates parton energy loss in hot medium.

Photon measurements help probe the initial collision stage and medium temperature.

pp collision data serve as baseline and input for fragmentation functions.

Abstract

Measurements of direct photon and neutral pion production in heavy-ion collisions provide a comprehensive set of observables characterizing properties of the hot QCD medium. Direct photons provide means to test the initial stage of an AA collision and carry information about the temperature and space-time evolution of the hot medium. Neutral pion suppression probes the parton energy loss in the hot medium. Measurements of neutral meson spectra in pp collisions at LHC energies $\sqrt{s}=$0.9, 2.76, 7 TeV serve as a reference for heavy-ion collisions and also provide valuable input data for parameterization of the QCD parton Fragmentation Functions. In this talk, results from the ALICE experiment on direct photon and neutral pion production in pp and Pb-Pb collisions are summarized.