Heavy-ion collisions - hot QCD in a lab

TL;DR

Heavy-ion collisions enable the study of quark-gluon plasma properties in laboratory conditions, revealing insights into strongly-interacting matter and early universe conditions through advanced experimental techniques.

Contribution

This paper introduces experimental methods and summarizes recent results in studying the quark-gluon plasma created in heavy-ion collisions.

Findings

QGP formation predicted by lattice QCD at high temperatures

Experimental probes reveal the properties and dynamics of the short-lived QGP

Results connect laboratory-created QGP to early universe conditions

Abstract

High-energy heavy-ion collisions provide a unique opportunity to study the properties of the hot and dense strongly-interacting system composed of deconfined quarks and gluons -- the quark-gluon plasma (QGP) -- in laboratory conditions. The formation of a QGP is predicted by lattice QCD calculations as a crossover transition from hadronic matter (at zero baryochemical potential) and is expected to take place once the system temperature reaches values above 155 MeV and/or the energy density above $0.5~\mathrm{GeV}/\mathrm{fm}^{3}$. The nature of such a strongly coupled QGP has been linked to the early Universe at some microseconds after the Big Bang. To characterize the physical properties of the short-lived matter (lifetime of about $10~\mathrm{fm}/c$) experimental studies at Relativistic Heavy-Ion Collider and the Large Hadron collider use auto-generated probes, such as high-energy partons created early in the hadronic collisions, thermally emitted photons, and a set of particle correlations that are sensitive to the collective expansion and the dynamics of the system. The lectures briefly introduced some of the experimental techniques and provided a glimpse at some of the results.