Modification of Jet Structure in High-Multiplicity pp Collisions due to Multiple-Parton Interactions and Observing a Multiplicity-Independent Characteristic Jet Size

Zoltán Varga,Gergely Gábor Barnaföldi,Róbert Vértesi

doi:10.1155/2019/6731362

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 nontrivial 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 nontrivial 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.

Highlights

High-multiplicity events of small colliding systems at high center-of-mass energies show similar collective features to those observed in events of heavy-ion collisions with comparable multiplicities, such as long-range near-side correlations and Vn (“flow”) coefficients [1, 2]
We investigate the effects caused by the choice of the color reconnection (CR) scheme within PYTHIA on the simulated jet structures
For high multiplicity the jet shape behaves in the opposite way

Summary

Introduction

High-multiplicity events of small colliding systems at high center-of-mass energies show similar collective features to those observed in events of heavy-ion collisions with comparable multiplicities, such as long-range near-side correlations and Vn (“flow”) coefficients [1, 2]. A recent study suggests to verify a possible existence of a QGP-droplet by measuring properties of jets in association with a Z-boson in ultra-central pp collisions [10]. Another suggestion is to measure the structures of photontagged recoil jets in comparison to inclusive jets.

Simulation and Analysis

Results

Summary