# Asymptotics of transverse momentum broadening in dense QCD media

### Submission summary

 As Contributors: Paul Caucal Arxiv Link: https://arxiv.org/abs/2111.01088v1 (pdf) Date accepted: 2022-03-01 Date submitted: 2021-11-02 11:29 Submitted by: Caucal, Paul Submitted to: SciPost Physics Proceedings Proceedings issue: 50th International Symposium on Multiparticle Dynamics (ISMD2021) Academic field: Physics Specialties: High-Energy Physics - Phenomenology Nuclear Physics - Theory Approach: Theoretical

### Abstract

We study the asymptotic behaviour of the transverse momentum broadening distribution of an energetic quark or gluon propagating through dense QCD matter, in the large system size $L$ limit, taking into account radiative corrections in the double logarithmic approximation. Thanks to a connection between the evolution of the jet quenching parameter $\hat{q}$ and the formation of traveling wave fronts in nonlinear physics, we obtain a formula for the $L$ dependence of the characteristic transverse momentum scale $Q_s$ of the distribution valid up to terms of order $1/\ln(L)$. We briefly discuss the physical implications of this formula for jet quenching and small-$x$ phenomenology.

###### Current status:
Publication decision taken: accept

Editorial decision: For Journal SciPost Physics Proceedings: Publish
(status: Editorial decision fixed and (if required) accepted by authors)

### Submission & Refereeing History

Submission 2111.01088v1 on 2 November 2021

## Reports on this Submission

### Strengths

Good context-setting in terms of jet quenching.

Mathematical content well explained, though relying on some expert knowledge of context. Reasonable within space constraints.

Good discussion of the interpretation of the results in terms of clearly explained Levy flights.

### Weaknesses

It would have been nice in the conclusions to go a little further in explaining the consequences of the Levy-flight behaviour in terms of "quenching power", i.e. if the <kT^2> distribution grows faster than from Brownian motion, does this imply a greater than naively expected broadening/quenching from QGP than from a "normal" medium? And is there a physical intuition for the super-diffusive behaviour, e.g. in terms of pQCD-correlated emissions?

A few minor spelling/grammar typos, below threshold for correction in proceedings.

### Report

A clearly written submission, covering a technical area with material accessible to generalists as well as specialists. Well suited for publication without revision.

• validity: high
• significance: high
• originality: high
• clarity: high
• formatting: excellent
• grammar: excellent