Neutral pion and $\eta$ meson production in proton-proton collisions at $\sqrt{s}$ = 8 TeV

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8 TeV
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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 neutral mesons $\pi^{0}$ and $\eta$ were measured in transverse momentum ranges of $0.3<\pT<35$~\GeVc and $0.5<\pT<35$~\GeVc, respectively. Next-to-leading order perturbative QCD calculations using fragmentation functions DSS14 for $\pi^{0}$ and AESSS for $\eta$ overestimate the cross sections of both neutral mesons, but agree with the measured $\eta/\pi^0$ ratio within uncertainties. The results are 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 \mT scaling for $\pT>3.5$~\GeVc. However, a deviation from this empirical scaling law is observed for transverse momenta below $\pT<3.5$~GeV/$c$ in the $\eta/\pi^0$ ratio with a significance of $6.2\sigma$.