Measurement of Neutral Pion Production at High $p_{\text{T}}$ in pp Collisions at $\sqrt{s} = 2.76$ TeV

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2.76 TeV
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The invariant differential cross sections for inclusive $\pz$ and $\eta$ mesons at midrapidity were measured in pp collisions at $\sqrt{s}=2.76$~TeV for transverse momenta $0.4<\pt<40$~GeV/$c$ and $0.6<\pt<20$~GeV/$c$, respectively, using the ALICE detector.
This large range in $\pt$ 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-$\pt$ neutral pions, which exploits that the showers originating from their decay photons overlap in the EMCal.
Above $4$~\gevc, 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 and generator-level simulations with \Pythia\ 8.2 describe the cross sections to about $30$\% for the $\pz$, and between $30$--$50$\% for the $\eta$ meson.
The new data can therefore be used to further improve the theoretical description of $\pz$ and $\eta$ meson production.