Energy Dependence of the Transverse Momentum Distributions of Charged Particles in pp Collisions Measured by ALICE

TL;DR

This paper measures the transverse momentum distributions of charged particles in proton-proton collisions at different energies, compares them to theoretical predictions, and discusses methods to create reference spectra for nuclear collision studies.

Contribution

It provides detailed measurements of $p_T$ spectra at multiple energies and proposes procedures to construct reference spectra for use in nuclear physics research.

Findings

Differential cross sections increase with collision energy.

NLO-pQCD describes the relative increase but not individual spectra.

Procedures for constructing reference spectra up to 50 GeV/c are discussed.

Abstract

Differential cross sections of charged particles in inelastic pp collisions as a function of $p_{\rm T}$ have been measured at $\sqrt{s}=$ 0.9, 2.76 and 7 TeV at the LHC. The $p_{\rm T}$ spectra are compared to NLO-pQCD calculations. Though the differential cross section for an individual $\sqrt{s}$ cannot be described by NLO-pQCD, the relative increase of cross section with $\sqrt{s}$ is in agreement with NLO-pQCD. Based on these measurements and observations, procedures are discussed to construct pp reference spectra at $\sqrt{s} =$ 2.76 and 5.02 TeV up to $p_{\rm T}$ = 50 GeV/$c$ as required for the calculation of the nuclear modification factor in nucleus-nucleus and proton-nucleus collisions.