Light neutral meson production in heavy ion collisions with ALICE in the era of precision physics at the LHC

TL;DR

This paper presents high-precision measurements of light neutral meson production in heavy-ion collisions at the LHC, providing insights into the Quark-Gluon Plasma and testing theoretical models with improved accuracy.

Contribution

It reports new ALICE Run 2 preliminary results on neutral meson spectra in pp and Pb--Pb collisions, enhancing measurement precision over a wide kinematic range.

Findings

Neutral meson spectra measured with high precision.

Results support and refine QGP energy loss models.

Improved understanding of QGP temperature and evolution.

Abstract

The production of light neutral mesons in AA collisions probes the physics of the Quark-Gluon Plasma (QGP), which is formed in heavy-ion collisions at the LHC. More specifically, the centrality dependent neutral meson spectra in AA collisions compared to its spectra in minimum-bias pp collisions, scaled with the number of hard collisions, provides information on the energy loss of partons traversing the QGP. The measurement allows to test with high precision the predictions of theoretical model calculations. In addition, the decay of the $\pi^{0}$ and $\eta$ mesons are the dominant backgrounds for all direct photon measurements. Therefore, pushing the limits of the precision of neutral meson production is key to learning about the temperature and space-time evolution of the QGP. In the ALICE experiment neutral mesons can be detected via their decay into two photons. The latter can be reconstructed using the two calorimeters EMCal and PHOS or via conversions in the detector material. The excellent momentum resolution of the conversion photons down to very low $p_{\mathrm{T}}$ and the high reconstruction efficiency and triggering capability of calorimeters at high $p_{\mathrm{T}}$, allow us to measure the $p_{\mathrm{T}}$ dependent invariant yield of light neutral mesons over a wide kinematic range. Combining state-of-the-art reconstruction techniques with the high statistics delivered by the LHC in Run 2 gives us the opportunity to enhance the precision of our measurements. In these proceedings, new ALICE run 2 preliminary results for neutral meson production in pp and Pb--Pb collisions at LHC energies are presented.