|Research Area||Plasma Physics|
|Principal Investigator(s)||Prof. Jonathan Flynn|
Quarks are the fundamental particles that make up 99.9 per cent of ordinary matter, such as protons and neutrons in atomic nuclei. Quarks are bound together by the strong nuclear force, mediated by the exchange of gluons. The theory describing the strong force is called Quantum Chromodynamics, or QCD. The strong force is actually weak when the quarks are close together but increases steadily as you try to separate them, making it impossible to isolate a single quark, a property known as ’confinement’. This means that in experiments we detect not quarks and gluons but particles which are complicated bound states. The basic properties of the six types or flavours of quarks, such as their masses or the strengths of the interactions which turn one type of quark into another, are thus very hard to determine. The interactions changing one flavour to another are related to the small difference between matter and antimatter, called CP violation, that may help to explain why our Universe is dominated by matter (and hence why we can exist at all).
Supercomputer simulations are needed to discover whether our current theories can explain this or if there is some new physics at work. The simulations are the vital link between fundamental theories and the observed particle interactions seen in high energy physics experiments. The calculations enable scientists to ’look inside’ quark and gluon bound states, such as the proton and a plethora of other states known collectively as hadrons. The calculation is performed by constructing a discrete four dimensional space-time grid (the lattice) and then solving the QCD equations of motion on this grid. Such lattice QCD simulations are the only known first-principles method for studying hadronic interactions.