Forward-backward correlations and charged-particle azimuthal distributions in pp interactions using the ATLAS detector

TL;DR

This paper reports measurements of forward-backward charged-particle correlations and azimuthal distributions in proton-proton collisions at 900 GeV and 7 TeV using the ATLAS detector, comparing results with Monte Carlo models.

Contribution

First measurement of forward-backward correlations in both multiplicity and summed transverse momentum in pp collisions at LHC energies.

Findings

Monte Carlo models generally agree with the data

Charged-particle azimuthal distributions reveal jet-like structures

Forward-backward correlations vary with collision energy

Abstract

Using inelastic proton-proton interactions at sqrt(s) = 900 GeV and 7 TeV, recorded by the ATLAS detector at the LHC, measurements have been made of the correlations between forward and backward charged-particle multiplicities and, for the first time, between forward and backward charged-particle summed transverse momentum. In addition, jet-like structure in the events is studied by means of azimuthal distributions of charged particles relative to the charged particle with highest transverse momentum in a selected kinematic region of the event. The results are compared with predictions from tunes of the PYTHIA and HERWIG++ Monte Carlo generators, which in most cases are found to provide a reasonable description of the data.