Neutral meson production in pp and Pb-Pb collisions measured by ALICE at the LHC

TL;DR

This paper reports measurements of neutral pion production and suppression in Pb-Pb and pp collisions at 2.76 TeV, revealing increased suppression with collision centrality and consistent associated particle yields.

Contribution

It provides new measurements of neutral pion nuclear modification factors and associated particle yields in heavy-ion collisions at the LHC.

Findings

Neutral pion suppression increases with collision centrality.

Associated particle yields are consistent with charged particle measurements.

Transverse momentum spectra are measured up to 12 GeV/c for Pb-Pb and 10 GeV/c for pp.

Abstract

The midrapidity $\pi^0$ nuclear modification factor, $R_{\rm{AA}}$, at $\sqrt{s_\mathrm{NN}} =$ 2.76 TeV in 6 centrality classes as well as the corresponding $\pi^0$ invariant yields in Pb-Pb and in pp collisions are presented. The transverse momentum range covered is 0.6 (0.4) GeV/$c$ $< p_{\mathrm{T}} <$ 12 (10) GeV/$c$ for Pb-Pb (pp) collisions. A suppression of neutral pions increasing with centrality is observed. The yield of charged particles associated with a high $p_{\mathrm{T}}$ neutral pion trigger (8 GeV/$c$ $< p_{\mathrm{T}} <$ 16 GeV/$c$) is measured in pp and Pb-Pb collisions at $\sqrt{s_\mathrm{NN}} =$ 2.76 TeV. The conditional per-trigger yield modification factor in the near and away side is in agreement with the measured one for charged particles.