Meson properties from lattice QCD

Abstract

Quantum Chromo - Dynamics ( QCD ) is the part of the Standard Model which describes the interaction of the strong nuclear force with matter. QCD is asymptotically free, so at high energies perturbation expansions in the coupling can be used to calculate expectation values. Away from this limit, however, perturbation expansions in the coupling do not converge. Lattice QCD ( LQCD ) is a non - perturbative approach to calculations in QCD. LQCD first performs a Wick rotation t → - it [subscript E], and then discretises spacetime into a regular lattice with some lattice spacing a. QCD is then expressed in terms of parallel transport operators of the gauge field between grid points, and fermion fields which are defined at the grid points. Operators are evaluated in terms of these quantities, and the lattice spacing is then taken to zero to recover continuum values. We perform computer simulations of Lattice QCD in order to extract a variety of meson observables. In particular, we perform a comprehensive survey of the light and strange meson octets, obtain for the first time exotic meson results consistent with experiment, calculate the charge form - factor of the light and strange pseudoscalar mesons, and determine ( for the first time in Lattice QCD ) all three form - factors of the vector meson.