A Study of the Energy Dependence of the Underlying Event in Proton-Antiproton Collisions

TL;DR

This paper investigates how the underlying event in proton-antiproton collisions varies with energy, providing detailed measurements that can enhance QCD models for future high-energy collider experiments.

Contribution

It offers a comprehensive analysis of the energy dependence of underlying event components in proton-antiproton collisions, aiding model refinement for LHC energies.

Findings

Transverse region activity increases with energy.

Separation of hard and soft components improves modeling.

Data constrains Monte Carlo simulations at high energies.

Abstract

We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.