Traditionally the atomic nucleus has been regarded as a collection of bound protons and neutrons.
However, with the discovery of quarks and a more fundamental theory of the strong interaction, namely Quantum Chromodynamics, it has become clear that the old view needs to be replaced.
The change of the properties of protons and neutrons in matter is the topic of a great deal of research effort around the world.
It seems likely that such changes may be critical to understanding the equation of state of dense matter and hence the properties of neutron stars. Having a quark-level understanding of dense matter will also be necessary in order to explore the phase transition to quark matter at high density and temperature. Finally, the nucleon-nucleon force itself also needs to be derived from the quark level.
The theoretical physics research activities are primarily carried out under the umbrella of the ARC Centre for the Subatomic Structure of Matter (CSSM).