Medium-induced radiation with vacuum propagation in the pre-hydrodynamics phase

Abstract

The recent discovery of the potential of jet quenching observables to constrain the initial stages after a heavy-ion collision makes imperative to have a better understanding of the process of medium-induced radiation before the formation of the quark-gluon plasma (QGP) and its impact on observables at high-$p_T$. In this work, we generalize the BDMPS-Z framework for medium-induced radiation to account for additional emissions occurring before the creation of the QGP. For simplicity, we assume that during the pre-hydrodynamics phase the hard parton propagates as in vacuum. This set-up, allows us to isolate the contribution from the additional initial radiation by comparing with the usual scenarios in which the emitter is created inside the medium but with different starting points. Using both a numerical implementation of the fully resummed emission spectrum and the usual analytical approximations, we find that replacing an initial slab of the medium by vacuum yields to a significant reduction of the emission spectrum for low radiated gluon energies, while the high-energy tails remain largely unmodified. Finally, we assess the effect of replacing the initial medium by vacuum propagation on the single-inclusive particle suppression $R_{AA}$ and high-$p_T$ azimuthal asymmetry $v_2$. Our findings indicate that considering vacuum propagation prior to hydrodynamization leads to an increase in the $v_2$, thus corroborating the importance of the treatment of jet quenching in the initial stages for the correct description of both observables.

25 pages, 9 figures. Matches published version in JHEP

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Cited by in corpus (9)

• Simulating jets and heavy quarks in the Glasma using the colored particle-in-cell method
• Precise description of medium-induced emissions
• Jet quenching parameter in QCD kinetic theory
• Heavy flavor angular correlations as a direct probe of the glasma
• The impact of glasma on heavy flavor azimuthal correlations and spectra
• Exploring the time axis within medium-modified jets
• Bayesian Constraints on Pre-Equilibrium Jet Quenching and Predictions for Oxygen Collisions
• In-medium gluon radiation spectrum with all-order resummation of multiple scatterings in longitudinally evolving media
• Jet quenching in out-of-equilibrium QCD matter