Nuclear modification factor of light neutral-meson spectra up to high transverse momentum in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV

TL;DR

This paper measures neutral meson production at high transverse momentum in p-Pb collisions at 8.16 TeV, providing insights into nuclear effects and constraining nuclear parton distribution models.

Contribution

It extends the transverse momentum range of neutral meson spectra measurements in p-Pb collisions at 8.16 TeV, offering new data to test nuclear modification models.

Findings

$R_{pPb}$ below unity for $p_T<10$ GeV/c

$R_{pPb}$ consistent with unity for $p_T>10$ GeV/c

No significant final state energy loss observed

Abstract

Neutral pion ($\pi^{0}$) and $\eta$ meson production cross sections were measured up to unprecedentedly high transverse momenta ($p_{\rm T}$) in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV. The mesons were reconstructed via their two-photon decay channel in the rapidity interval $-1.3< y <0.3$ in the ranges of $0.4<p_{\rm T}<200$ GeV/$c$ and $1.0<p_{\rm T}<50$ GeV/$c$, respectively. The respective nuclear modification factor ($R_{\rm pPb}$) is presented for $p_{\rm T}$ up to of 200 and 30 GeV/$c$, where the former was achieved by extending the $\pi^{0}$ measurement in pp collisions at $\sqrt{s}$ = 8 TeV using the merged cluster technique. The values of $R_{\rm pPb}$ are below unity for $p_{\rm T}<10$ GeV/$c$, while they are consistent with unity for $p_{\rm T}>10$ GeV/$c$, leaving essentially no room for final state energy loss. The new data provide strong constraints for nuclear parton distribution and fragmentation functions over a broad kinematic range and are compared to model predictions as well as previous results at $\sqrt{s_{\rm NN}}$ = 5.02 TeV.