Transverse momentum distribution and nuclear modification factor of forward neutral pion in proton--lead collisions at $\sqrt{s_{NN}}=5.02$TeV

Abstract

The transverse momentum ($p_{\text{T}}$) distribution for inclusive neutral pions in the very forward rapidity region has been measured, with the Large Hadron Collider forward detector (LHCf), in proton--lead collisions at nucleon-nucleon center-of-mass energies of $\sqrt{s_{NN}}=5.02$TeV at the LHC. The $p_{\text{T}}$ spectra obtained in the rapidity range $-11.0<y_{\text{lab}}<-8.9$ and $0<p_{\text{T}}<0.6$GeV (in the detector reference frame) show a strong suppression of the production of neutral pions after taking into account ultra-peripheral collisions. This leads to a nuclear modification factor value, relative to the interpolated $p_{\text{T}}$ spectra in proton-proton collisions at $\sqrt{s}=5.02$TeV, of about 0.1--0.4. This value is compared with the predictions of several hadronic interaction Monte Carlo simulations.

13 pages, 7 figures; 9 tables, accepted in Phys. Rev. C