Photon and neutral pion production in pp and Pb-Pb collisions at LHC energies in the ALICE experiment

TL;DR

This paper reports on measurements of direct photon and neutral pion production in proton-proton and lead-lead collisions at LHC energies, providing insights into QCD validation and medium effects in heavy-ion collisions.

Contribution

It provides new experimental data on neutral pion and direct photon yields in pp and Pb-Pb collisions, testing QCD models and exploring medium-induced photon excess in heavy-ion collisions.

Findings

Neutral pion production tests QCD models in pp collisions.

Pb-Pb collisions show medium-induced suppression of neutral pions.

Excess of low-momentum photons in central Pb-Pb collisions indicates high-temperature matter.

Abstract

We present the results for direct photon and neutral pion production obtained from proton-proton and lead-lead collisions in the ALICE experiment. Measurement of neutral pions in pp collisions allows to test the validity of QCD-inspired models. The study of neutral pion yields in Pb-Pb collisions permits to study the medium-induced suppression relative to the pp case. The yield of direct photons is compared to perturbative QCD calculations. In the case of central Pb-Pb collisions the observed excess of photons below 4 GeV/c is used to find the effective temperature of the matter.