Why QCD needs high performance computing

The study of Quantum Chromodynamics (QCD) remains one of the most challengi ng topics in elementary particle physics. The lattice formulation of QCD, i n which space-time is treated as a four-dimensional hypercubic grid of poin ts, provides the means for a numerical solution from first principles but m akes extreme demands upon computational performance. High Performance Compu ting (HPC) offers us the tantalizing prospect of a verification of QCD thro ugh the precise reproduction of the known masses of the strongly interactin g particles. It is also leading to the development of a phenomenological to ol capable of disentangling strong interaction effects from weak interactio n effects in the decays of one kind of quark into another, crucial for dete rmining parameters of the Standard Model of particle physics. We give a ped agogical review of lattice QCD, outline the computational methodology used and discuss the sources of systematic error that arise in numerical calcula tions. We describe progress in reducing discretization errors through the u se of improved formulations of lattice QCD and present a selection of recen t results. (C) 1999 Elsevier Science B.V. All rights reserved.