Perfect QCD -- a new Universal approach to soft QCD

TL;DR

This paper proposes a universal, strongly coupled framework for soft QCD processes in hadronic collisions, emphasizing coherent excitations and radiation, to better understand phenomena like particle production and flow in small systems.

Contribution

It introduces the concept of 'perfect QCD' as a guiding principle, suggesting a new microscopic model where initial state screening and coherent excitations dominate particle production.

Findings

Multi-parton interactions are negligible due to large initial state screening.

Particle production is primarily driven by radiation from excited remnants.

The model explains the absence of jet quenching and predicts flow in small systems.

Abstract

The ideas presented in this proceeding aims to be a first step towards a description of hadronic collisions where all soft processes are fundamentally strongly coupled and the same Universal strongly coupled physics drives both initial and final-state interactions. As it is not currently possible to derive such a picture from first principles, instead, an attempt to generalize the perfect liquid observation to a ``perfect QCD'' guiding principle is presented, focusing on implications for particle production in small systems. The first steps towards a microscopic model is taken by arguing that ``perfect QCD'' suggests that the screening in the initial state is so large that multi-parton interactions are of little or no importance. Instead, a target and projectile remnant is coherently excited and particle production is mainly driven by radiation in a qualitative similar manner as $e^+e^- \rightarrow q\bar{q}$. Finally, some of the possible implications of this ``excited remnant model'' are presented. It is argued that the time ordering of soft and hard physics can explain the absence of jet quenching in small systems and that the coherence scale of the projectile and target provides insights into what small systems will exhibit flow.