Production of \(\pi^0\) and \(\eta\) mesons up to high transverse momentum in pp collisions at 2.76 TeV

Abstract

The invariant differential cross sections for inclusive \(\pi^{0}\) and \(\eta\) mesons at midrapidity were measured in pp collisions at \(\sqrt{s}=2.76\) TeV for transverse momenta \(0.4<p_{\rm T}<40\) GeV/\(c\) and \(0.6<p_{\rm T}<20\) GeV/\(c\), respectively, using the ALICE detector. This large range in \(p_{\rm T}\) was achieved by combining various analysis techniques and different triggers involving the electromagnetic calorimeter (EMCal). In particular, a new single-cluster, shower-shape based method was developed for the identification of high-\(p_{\rm T}\) neutral pions, which exploits that the showers originating from their decay photons overlap in the EMCal. The measured cross sections are found to exhibit a similar power-law behavior with an exponent of about \(6.3\), Next-to-leading-order perturbative QCD calculations differ from the measured cross sections by about \(30\)% for the \(\pi^0\), and between \(30\)-\(50\)% for the \(\eta\) meson, while generator-level simulations with PYTHIA 8.2 describe the data to better than \(10\)-\(30\)%, except at \(p_{\rm T}<1\) GeV/\(c\), The new data can therefore be used to further improve the theoretical description of \(\pi^{0}\) and \(\eta\) meson production.