The strong interaction, QCD, has a rich phase structure, much of which is not fully understood. At low temperatures and densities, the interaction has a linearly rising potential and the familiar confining properties where quarks are bound into hadrons. At temperatures above 156 MeV, QCD exists as a weakly interacting “quark gluon plasma” where hadrons typically are no longer bound. The plasma phase existed briefly in the very early Universe, and can be reproduced in heavy-ion collision experiments in CERN and the Brookhaven Laboratory.
This talk will review studies of the QCD phase structure using lattice gauge theory. I will present recent work with the Adelaide group on centre vortices - topological structures which can give hints about the confinement mechanism. Analyses of the hadronic spectrum from our FASTSUM lattice collaboration in both the confined and plasma phase will be summarised.