# Quenching of Hadron Spectra in Heavy Ion Collisions at the LHC

## TL;DR

This paper demonstrates that the nuclear modification factor in heavy ion collisions at the LHC follows a universal pattern that can be modeled with energy loss theory, revealing insights into medium properties and quenching effects.

## Contribution

It introduces a simple energy loss model based on the BDMPS spectrum that accurately reproduces the universal shape of $R_{AA}$ across various hadrons and energies, and proposes a data-driven method to determine quenching parameters.

## Key findings

- Universal $R_{AA}$ shape across hadron species and energies
- Transport coefficient increases by 10-20% from 2.76 TeV to 5.02 TeV
- Model enables extraction of quenching weight moments without prior assumptions

## Abstract

The $p_\perp$ dependence of the nuclear modification factor $R_{\rm AA}$ measured in PbPb collisions at the LHC exhibits a universal shape, which can be very well reproduced in a simple energy loss model based on the BDMPS medium-induced gluon spectrum. The scaling is observed for various hadron species ($h^\pm$, $D$, $J/\psi$) in different centrality classes and at both colliding energies, $\sqrt{s}=2.76$ TeV and $\sqrt{s}=5.02$ TeV. Results indicate an 10-20% increase of the transport coefficient from $\sqrt{s}=2.76$ TeV to $\sqrt{s}=5.02$ TeV, consistent with that of particle multiplicity. Based on this model, a data-driven procedure is suggested, which allows for the determination of the first and second moments of the quenching weight without any prior knowledge of the latter.