# Extraction of multiple parton interactions and color reconnection from forward-backward multiplicity correlations

## TL;DR

This study uses PYTHIA simulations to analyze forward-backward multiplicity correlations in proton-proton collisions at LHC energies, highlighting the roles of multiple parton interactions and color reconnection in explaining experimental data.

## Contribution

It demonstrates that combining multiple parton interactions and color reconnection effects is necessary to reproduce observed correlations and proposes a method to estimate the number of parton interactions from these correlations.

## Key findings

- Color reconnection and multiple parton interactions are essential to explain correlations.
- The analysis allows estimation of the average number of parton interactions.
- Predictions for correlation strength at higher energies are provided.

## Abstract

Forward-backward multiplicity correlations have been studied in electron-positron, proton-proton and more recently in lead-lead collisions. For the proton-proton case, comparison of experimental results to different models reveals an incomplete understanding of the physical phenomenon associated with these correlations. In this work, we present a study of forward-backward multiplicity correlations in proton-proton collisions using the PYTHIA event generator, at LHC energies. A detailed analysis is presented with and without weak decays, splitting data samples into soft and hard QCD processes, and comparing the computed correlations for short and long range pseudorapidity regions. Each of these regions is analyzed accounting for the effects of color reconnection and independent multiple parton interactions. We show that a combination of these effects is required to explain the latest measurements on proton-proton data. Furthermore, is shown that from measurements of multiplicity correlations is possible to extract the average number of multiple parton interactions in the event producing these correlations, and albeit model depending, to predict the strength of these correlations, not yet measured, for higher energy collisions.