# Update of a Multi-Phase Transport Model with Modern Parton Distribution Functions and Nuclear Shadowing

## TL;DR

This paper updates the AMPT model with modern parton distribution functions and nuclear shadowing, improving its ability to describe particle production in heavy ion collisions at RHIC and LHC energies.

## Contribution

The authors incorporate modern PDFs and impact parameter-dependent nuclear shadowing into the AMPT model, and refit parameters to experimental data for better accuracy.

## Key findings

- Updated AMPT model describes particle yields and spectra well at RHIC and LHC energies.
- Nuclear scaling of minijet transverse momentum cutoff improves model predictions for $AA$ collisions.
- Enhanced reliability for heavy flavor and high-$p_T$ particle predictions.

## Abstract

A multi-phase transport (AMPT) model has been successful in explaining a wide range of observables in relativistic heavy ion collisions. In this work, we implement a modern set of free proton parton distribution functions and an impact parameter-dependent nuclear shadowing in the AMPT model. After refitting the parameters of the two-component initial condition model to the experimental data on $pp$ and $p \bar p$ total and inelastic cross sections from $\sqrt s \sim $ 4 GeV to 13 TeV, we study particle productions in $pp$ and $AA$ collisions. We show that the updated AMPT model with string melting can reasonably describe the overall particle yields and transverse momentum spectra for both $pp$ and $AA$ collisions at RHIC and LHC energies after we introduce a nuclear scaling of the minijet transverse momentum cutoff for $AA$ collisions at LHC energies that is motivated by the color glass condensate. Since heavy flavor and high-$p_{\rm T}$ particles are produced by perturbative-QCD processes and thus directly depend on parton distribution functions of nuclei, the updated AMPT model is expected to provide a more reliable description of these observables.