Underlying Event Studies for LHC Energies

TL;DR

This paper refines the definition of the underlying event in proton-proton collisions at LHC energies, especially for multi-jet events, by introducing surrounding rings and belts to better isolate the underlying event characteristics.

Contribution

It proposes a new geometric-based definition of the underlying event using surrounding rings and belts, improving analysis for multi-jet events at LHC energies.

Findings

Effective separation of underlying event from jet activity.

Analysis of multiplicity in defined geometries.

Study of mean transverse momentum in different regions.

Abstract

Underlying event was originally defined by the CDF collaboration decades ago. Here we improve the original definition to extend our analysis for events with multiple-jets. We introduce a definition for surrounding rings/belts and based on this definition the jet- and surrounding-belt-excluded areas will provide a good underlying event definition. We inverstigate our definition via the multiplicity in the defined geometry. In parallel, mean transverse momenta of these areas also studied in proton-proton collisions at $\sqrt{s}=7$ TeV LHC energy.