# Study of angular correlations in Monte Carlo simulations

## TL;DR

This paper analyzes two-particle angular correlations in Monte Carlo simulations of Pb-Pb collisions, comparing models to experimental data to understand jet structures and their dependence on collision parameters.

## Contribution

It evaluates the near-side peak shape in angular correlations using Monte Carlo models, highlighting differences between AMPT and PYTHIA 8.235/Angantyr in reproducing experimental results.

## Key findings

- AMPT model better matches ALICE data than PYTHIA 8.235/Angantyr.
- Near-side peak variances depend on collision centrality and transverse momentum.
- Transport models provide more accurate correlation shapes than string fragmentation models.

## Abstract

In two-particle angular correlation measurements the distribution of charged hadron pairs are evaluated as a function of pseudorapidity ($\Delta \eta$) and azimuthal ($\Delta \varphi$) differences. In these correlations, jets manifest themselves as a near-side peak around $\Delta \eta = 0,$ $\Delta \varphi = 0$. These correlations can be used to extract transverse momentum ($p_T$) and centrality dependence of the shape of the near-side peak in Pb-Pb collision. The shape of the near-side peak is quantified by the variances of the distribution. The variances are evaluated from a fit combining the peak and the background. In this contribution, identified and unidentified angular correlations are shown from Pb-Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV from Monte Carlo simulations (AMPT, PYTHIA 8.235/Angantyr). Results show that transport models in AMPT give better results than PYTHIA 8.235/Angantyr when comparing to the experimental results of the ALICE collaboration.