# Neutral meson production and correlation with charged hadrons in pp and Pb-Pb collisions with the ALICE experiment at the LHC

## TL;DR

This paper presents measurements of neutral meson production and their correlations with charged hadrons in proton-proton and lead-lead collisions at the LHC, providing insights into parton energy loss and medium properties of the Quark-Gluon Plasma.

## Contribution

It reports new measurements of neutral mesons and azimuthal correlations in pp and Pb-Pb collisions at 2.76 TeV, including the per-trigger yield modification factor $I_{AA}$, with comparisons to theoretical models.

## Key findings

- Neutral meson production measured at 2.76 TeV in pp collisions.
- Azimuthal $b0$-hadron correlations analyzed in pp and Pb-Pb collisions.
- Observed modifications in yield consistent with medium-induced energy loss effects.

## Abstract

Among the probes used to investigate the properties of the Quark-Gluon Plasma, the measurement of the energy loss of high-energy partons can be used to put constraints on energy-loss models and to ultimately access medium characteristics, such as the energy density or the temperature. The study of two-particle correlations allows us to obtain very different constraints compared to the nuclear modification factor. In particular, the correlation of charged hadrons with high energy $\pi^{0}$ or direct photons is believed to give a measurement of the parton energy loss and insights into the medium-induced modification of the fragmentation process. High energy neutral pions are reconstructed using the ALICE electromagnetic calorimeters EMCal and PHOS, and the charged particles are detected by the main tracking detectors ITS and TPC. In these proceedings, the measurement of neutral mesons at $\sqrt{s} = $2.76 TeV in pp collisions are presented, as well as the measurements of azimuthal $\pi^{0}$-hadron correlations in pp and Pb-Pb collisions at $\sqrt{s_{\rm{NN}}} = 2.76$~TeV, and the extracted per-trigger yield modification factor ($I_{AA}$). Comparisons with theoretical model calculations are also added.