KNO-like scaling within a jet in proton--proton collisions at LHC energies

TL;DR

This study uses PYTHIA 8 simulations to show that KNO scaling applies within jets in proton-proton collisions at LHC energies, revealing how certain interactions affect this scaling.

Contribution

It demonstrates the presence of KNO scaling within jets and clarifies the roles of MPI and color reconnection in its violation at high energies.

Findings

KNO scaling holds within jets without MPI.

MPI without color reconnection breaks KNO scaling.

Parton shower and MPI influence KNO scaling at high energies.

Abstract

We study the multiplicity distributions of events with hard jets in proton-proton collisions at LHC energies using PYTHIA 8 Monte-Carlo simulations. We demonstrate that the charged-hadron multiplicity distributions scale with jet momentum. This suggests that the Koba--Nielsen--Olesen (KNO) scaling holds within a jet. The in-jet scaling is fulfilled without multiple-parton interactions (MPI), but breaks down in case MPI is present without color reconnection. Our findings imply that KNO scaling is violated by parton shower or multiple-parton interactions in higher-energy collisions.