# Jet quenching as a probe of the initial stages in heavy-ion collisions

## TL;DR

This paper demonstrates that jet quenching observables can serve as sensitive probes of the initial stages of heavy-ion collisions, providing insights into the early non-equilibrium dynamics and thermalization process.

## Contribution

It introduces a novel approach showing that combined jet quenching measurements can constrain the early-time energy loss and thermalization in heavy-ion collisions.

## Key findings

- Energy loss must be suppressed in the first 0.6 fm after collision.
- Jet observables can constrain initial non-equilibrium dynamics.
- Potential for more sophisticated jet measurements to refine understanding.

## Abstract

Jet quenching provides a very flexible variety of observables which are sensitive to different energy- and time-scales of the strongly interacting matter created in heavy-ion collisions. Exploiting this versatility would make jet quenching an excellent chronometer of the yoctosecond structure of the evolution process. Here we show, for the first time, that a combination of jet quenching observables is sensitive to the initial stages of heavy-ion collisions, when the approach to local thermal equilibrium is expected to happen. Specifically, we find that in order to reproduce at the same time the inclusive particle production suppression, $R_{AA}$, and the high-$p_T$ azimuthal asymmetries, $v_2$, energy loss must be strongly suppressed for the first $\sim 0.6$ fm. This exploratory analysis shows the potential of jet observables, possibly more sophisticated than the ones studied here, to constrain the dynamics of the initial stages of the evolution.