Production of π0 and η mesons up to high transverse momentum in pp collisions at 2.76 TeV

Abstract

The invariant differential cross sections for inclu- sive π0 and η mesons at midrapidity were measured in pp collisions at √s = 2.76 TeV for transverse momenta 0.4<pT<40GeV/cand0.6<pT<20GeV/c,respec- tively, using the ALICE detector. This large range in pT was achieved by combining various analysis techniques and different triggers involving the electromagnetic calorime- ter (EMCal). In particular, a new single-cluster, shower-shape based method was developed for the identification of high- pT neutral pions, which exploits that the showers originat- ing from their decay photons overlap in the EMCal. Above 4 GeV/c, 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 π0, and between 30–50% for the η meson, while generator-level simulations with PYTHIA 8.2 describe the data to better than 10–30%, except at pT < 1 GeV/c. The new data can there- fore be used to further improve the theoretical description of π0 and η meson production.