Measurements of charged particle spectra and nuclear modification factor in p+Pb collisions with the ATLAS detector

TL;DR

This paper reports measurements of charged particle spectra and the nuclear modification factor in p+Pb collisions at 5.02 TeV using the ATLAS detector, revealing significant variations with transverse momentum and collision centrality.

Contribution

The study provides the first detailed measurements of the nuclear modification factor in p+Pb collisions at this energy with wide rapidity coverage.

Findings

Nuclear modification factor varies with transverse momentum.

Stronger dependence observed in peripheral collisions.

Data enables comparison with theoretical models.

Abstract

The ATLAS detector at the LHC obtained the sample of p+Pb data at $\sqrt{s_{NN}}={}$5.02TeV with integrated luminosity of 25nb${}^{-1}$, which can be compared to the pp data obtained by interpolating pp measurements at $\sqrt{s}={}$2.76TeV and 7TeV. Due to the excellent capabilities of the ATLAS detector, and its stable operation in heavy ion as well as proton-proton physics runs, the data allow measurements of the nuclear modification factor, ratio of heavy ion charged particle spectra divided by pp reference, in different centrality classes over a wide range of rapidity. The charged particle nuclear modification factor is found to vary significantly as a function of transverse momentum with a stronger dependence in more peripheral collisions.