Angular Dependence of Jet Quenching Indicates Its Strong Enhancement Near the QCD Phase Transition

TL;DR

This paper investigates how jet quenching varies with matter density near the QCD phase transition, revealing a strong enhancement in the near-$T_c$ region and suggesting magnetic monopoles may play a role.

Contribution

It introduces a layer-wise geometrical limit for jet quenching and demonstrates that quenching is significantly stronger near the critical temperature, supported by models fitting RHIC data.

Findings

Jet quenching is dominated by the near-$T_c$ region.

The geometrical limit $v_2^{max}$ exceeds experimental data.

Jet quenching is several times stronger near $T_c$ than at higher temperatures.

Abstract

We study dependence of jet quenching on matter density, using "tomography" of the fireball provided by RHIC data on azimuthal anisotropy $v_2$ of high $p_t$ hadron yield at different centralities. Slicing the fireball into shells with constant (entropy) density, we derive a "layer-wise geometrical limit" $v_2^{max}$ which is indeed above the data $v_2<v_2^{max}$. Interestingly, the limit is reached only if quenching is dominated by shells with the entropy density exactly in the near-$T_c$ region. We show two models that simultaneously describe the high $p_t$ $v_2$ and $R_{AA}$ data and conclude that such a description can be achieved only if the jet quenching is few times stronger in the near-$T_c$ region relative to QGP at $T>T_c$. One possible reason for that may be recent indications that the near-$T_c$ region is a magnetic plasma of relatively light color-magnetic monopoles.