\(\pi^0\) and \(\eta\) meson production in proton-proton collisions at \(\sqrt{s}=8\) TeV

Abstract

An invariant differential cross section measurement of inclusive \(\pi^{0}\) and \(\eta\) meson production at mid-rapidity in pp collisions at \(\sqrt{s}=8\) TeV was carried out by the ALICE experiment at the LHC. The spectra of \(\pi^{0}\) and \(\eta\) mesons were measured in transverse momentum ranges of \(0.3<p_{\rm T}<35\) GeV/\(c\) and \(0.5<p_{\rm T}<35\) GeV/\(c\), respectively. Next-to-leading order perturbative QCD calculations using fragmentation functions DSS14 for the \(\pi^{0}\) and AESSS for the \(\eta\) overestimate the cross sections of both neutral mesons, although such calculations agree with the measured \(\eta/\pi^{0}\) ratio within uncertainties. The results were also compared with PYTHIA~8.2 predictions for which the Monash~2013 tune yields the best agreement with the measured neutral meson spectra. The measurements confirm a universal behavior of the \(\eta/\pi^{0}\) ratio seen for NA27, PHENIX and ALICE data for pp collisions from \(\sqrt{s}=27.5\) GeV to \(\sqrt{s}=8\) TeV within experimental uncertainties. A relation between the \(\pi^{0}\) and \(\eta\) production cross sections for pp collisions at \(\sqrt{s}=8\) TeV is given by \(m_{\rm T}\) scaling for \(p_{\rm T}>3.5\) GeV/\(c\), However, a deviation from this empirical scaling rule is observed for transverse momenta below \(p_{\rm T}<3.5\) GeV/\(c\) in the \(\eta/\pi^0\) ratio with a significance of \(6.2\sigma\),