Energy dependence of light neutral meson $p_{\rm T}$ spectrum produced in pp collisions at the LHC measured in ALICE

TL;DR

This paper reports measurements of neutral meson spectra in proton-proton collisions at various LHC energies, revealing scaling behaviors and differences from lower-energy experiments, providing insights into particle production mechanisms.

Contribution

It provides the first comprehensive measurement of $ ext{π}^0$ and $ ext{η}$ meson spectra across multiple energies at the LHC, highlighting scaling violations and potential suppression of higher twist processes.

Findings

Observation of $x_T$-scaling at high $p_T$

Violation of $m_T$-scaling at low $p_T$

Reduced $x_T$-scaling exponents compared to RHIC

Abstract

We present the measurement of light neutral mesons, $\pi^{0}$ and $\eta$, in pp collisions at different center-of-mass energies obtained with the ALICE experiment at the LHC. The $\pi^{0}$ and $\eta$ mesons are measured via photons reconstructed by the electromagnetic calorimeters and the central tracking system. The invariant cross-section of $\pi^{0}$ and $\eta$ mesons are measured in a broad $p_{\rm T}$ range at $\sqrt{s} = 0.9, 2.76, 7, 5.02$ and 8 TeV. The spectra of $\pi^{0}$ and $\eta$ mesons measured in pp collisions at different collision energies show $x_{\rm T}$-scaling at high $p_{\rm T}$ and violation of $m_{\rm T}$-scaling at low $p_{\rm T}$. The smaller $x_{\rm T}$-scaling exponents of our measurements compared to RHIC may hint at a reduced importance of higher twist processes at LHC.