Constraining QCD transport coefficients in hadron colliders

Akihiko Monnai,B Pattison,T Sako,H Menjo,Y Itow

doi:10.1051/epjconf/201920812002

Akihiko Monnai, B Pattison + Show 3 more

Open Access

https://doi.org/10.1051/epjconf/201920812002

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Abstract

We review the phenomenology of relativistic nuclear collisions in the light of ultra-high energy cosmic ray physics. A novel phase of quantum chromodynamics called quark-gluon plasma is expected to appear in nuclear collisions at high energies. The produced hot matter is found to be well-described as a relativistic fluid with small viscosity. We show that the transport coefficient can be quantitatively extracted by comparing theoretical estimations of viscous hydrodynamic models to experimental data.

Highlights

The physics of relativistic nuclear collisions and that of ultra-high energy cosmic ray (UHECR) events share a common ground since the former has its roots in the study of multi-particle production introduced in the context of cosmic ray analyses [1]
While this is still lower t√han the typical energy scale of UHECR, which is about s = 300 TeV, we have in collider experiments the unique opportunity to perform detailed analyses of the nuclear collision events under a controlled environment
We have studied collective properties of the hot quantum chromodynamics (QCD) matter in relativistic nuclear collisions, which can be relevant in the analyses of ultra-high energy cosmic ray events

Summary

Introduction

The physics of relativistic nuclear collisions and that of ultra-high energy cosmic ray (UHECR) events share a common ground since the former has its roots in the study of multi-particle production introduced in the context of cosmic ray analyses [1]. Following construction of upgraded facilities, the beam energy has been increased by orders of magnitude since ; the top center-of-mass energy of proton-proton col√lisions at the CERN Large Hadron Collider (LHC) is s = 13 TeV While this is still lower t√han the typical energy scale of UHECR, which is about s = 300 TeV, we have in collider experiments the unique opportunity to perform detailed analyses of the nuclear collision events under a controlled environment. Au-Au collisions at a high-temperature phase of quantum chromodynamics (QCD) where quarks and gluons are deconfined from hadrons above 2 trillion degrees [6] It has been shown at RHIC and LHC that the QGP can be realized over various energies. The data show an excellent agreement with the nearly-perfect fluid picture, which indicates that the QGP is strongly coupled and locally thermalized This implies that one can use a relativistic hydrodynamic model for the effective description of the dynamical evolution of non-perturbative QCD systems. The transport and decay processes can be described using hadronic cascade models

Relativistic hydrodynamics and transport coefficients

Numerical analyses of heavy ion collisions

Summary and outlook