Modification of jet structure in high-multiplicity pp collisions due to multiple-parton interactions and observing a multiplicity-independent characteristic jet size

TL;DR

This paper investigates how high-multiplicity proton-proton collisions modify jet structures, revealing a characteristic jet size unaffected by multiplicity, and proposes experimental methods to study effects like multiple-parton interactions.

Contribution

It introduces a multiplicity-independent jet size measure and demonstrates how jet shape modifications can indicate underlying event effects such as MPI and CR.

Findings

Jet shape depends on event multiplicity.

A multiplicity-independent jet size is proposed.

Jet structure observables can differentiate simulation tunes.

Abstract

We study the multiplicity dependence of jet structures in pp collisions using Monte Carlo event generators. We give predictions for multiplicity-differential jet structures and present evidence for a non-trivial jet shape dependence on charged hadron event multiplicity, that can be used as a sensitive tool to experimentally differentiate between equally well-preforming simulation tunes. We also propose a way to validate the presence and extent of effects such as multiple parton interactions (MPI) or color reconnection (CR), based on the detection of non-trivial jet shape modification in high-multiplicity events at high pT. Using multiplicity-dependent jet structure observables in various pT windows might also help understanding the interplay between jet particles and the underlying event (UE). We introduce a multiplicity-independent characteristic jet size measure, and use a simplistic model to aid its physical interpretation.