Quantum Chromodynamics (QCD) describes the interactions of quarks and gluons through the force of nature called the strong force. It predicts in principle the masses and properties of their bound states, called hadrons. The proton and neutron are important hadrons, the key constituents of atomic nuclei. There are many other hadrons, however, made from the different types, or flavours, of quarks in different combinations and they range in mass from one tenth the proton mass to many times the proton mass. The calculation of hadron masses can only be done by numerical simulation of QCD on a lattice of space-time points. This is a numerical ‘Grand Challenge’ project and needs fast supercomputers to solve it. The calculations are important since, together with experimental results, they can test the Standard Model of particle physics precisely in a way that we hope will uncover inconsistencies that lead to new understanding of how particle physics works at a deeper level.

Glasgow and Edinburgh theorists work together as part of the UK-wide UKQCD collaboration in this area as well as with other groups internationally.

Calculations in lattice QCD can tell us about the internal structure of the proton |