Dijet Acoplanarity in CUJET3 as a Probe of the Nonperturbative Color Structure of QCD Perfect Fluids

TL;DR

This paper investigates how dijet acoplanarity in high-energy heavy-ion collisions can reveal nonperturbative effects in the QCD medium, comparing models with and without nonperturbative degrees of freedom.

Contribution

It introduces a comparative analysis of perturbative and nonperturbative models of the QCD medium using dijet acoplanarity as a probe, highlighting the sensitivity to nonperturbative effects.

Findings

Dijet acoplanarity is significantly larger in the nonperturbative sQGMP model.

Both models produce similar jet energy loss, fitting $R_{AA}$ data.

Dijet measurements can potentially identify nonperturbative QCD phenomena.

Abstract

Using the CUJET3=DGLV+VISHNU jet-medium interaction framework, we show that dijet azimuthal acoplanarity in high energy $A+A$ collisions is sensitive to possible non-perturbative enhancement of the jet transport coefficient, $\hat{q}(T,E)$, in the QCD crossover temperature $T\sim 150-300$ MeV range. With jet-medium couplings constrained by global RHIC\& LHC $\chi^2$ fits to nuclear modification data on $R_{AA}$, we compare predictions of the medium induced dijet transverse momentum squared, $Q_s^2\sim \langle \hat{q} L \rangle \sim \Delta\phi^2 E^2$, in two models of the temperature, $T$, and jet energy $E$ dependence of the jet medium transport coefficient, $\hat{q}(T,E)$. In one model, wQGP, only perturbative quark and gluon dof are assumed. In the second model, sQGMP, nonperturbative three component semi-Quark-Gluon and Magnetic Monopole dof are asssumed. We show that the dijet path averaged medium induced azimuthal acoplanarity, $\Delta\phi^2$, in sQGMP is robustly a factor of $\sim 2$ larger than in perturbative wQGP while the radiative energy loss in both models is nearly identical as required to fit the same single jet nuclear modification $R_{AA}$ data. Future A+A dijet acoplanarity measurements correlated with $R_{AA}$ and azimuthal asymmetry $v_n$ measurements therefore appears to be a promising strategy to search for possible signatures of critical opalescence like phenomena in the QCD confinement temperature range.