Measuring the light meson nuclear modification factor in p-Pb collisions over an unprecedented $p_{\text{T}}$ range with ALICE

TL;DR

This paper reports measurements of light neutral meson production in p-Pb and pp collisions at high energies, extending the $p_T$ range and analyzing nuclear modification factors with implications for understanding nuclear effects.

Contribution

It provides the first measurement of the nuclear modification factor for $ ext{pi}^0$ and $ exteta$ mesons over an unprecedented $p_T$ range at 8.16 TeV, combining multiple detection techniques.

Findings

$R_{pPb}$ is consistent with theoretical models like NLO pQCD, CGC, and energy loss.

Suppression at low $p_T$ increases with collision energy.

Spectra cover almost two orders of magnitude in $p_T$.

Abstract

Differential invariant cross sections of light neutral mesons in p-Pb collisions at $\sqrt{s_{\text{NN}}}$ = 8.16 TeV and in pp collisions at $\sqrt{s}$ = 8 TeV have been measured up to very high transverse momentum ($p_{\text{T}}$). By combining independent reconstruction techniques available in ALICE using the EMCal and PHOS calorimeters as well as the central barrel tracking detectors, the combined spectra cover almost two orders of magnitude in $p_{\rm T}$ for the $\pi^{0}$ meson. The nuclear modification factor $R_{\text{pPb}}$ has been measured for the $\pi^{0}$ and $\eta$ mesons and is found to be consistent with NLO pQCD, CGC and energy loss calculations. Comparisons to the $R_{\text{pPb}}$ of $\pi^{0}$ measured in $\sqrt{s_{\text{NN}}}$ = 5.02 TeV hint at a stronger suppression at low $p_{\rm T}$ with increasing collision energy.