Masses and Boost-Invariant Wave Functions of Heavy Quarkonia from the Light-Front Hamiltonian of QCD

A new scheme for calculating masses and boost-invariant wave functions of heavy quarkonia is developed in a light-front Hamiltonian formulation of QCD. Only the simplest approximate version with one flavor of quarks and an ansatz for the mass gap for gluons is discussed. The resulting spectra look reasonably good in view of the crude approximations made in the simplest version.Comment: Talk at The Seventh Workshop on Continuous Advances in QCD, W.I.Fine Theoretical Physics Institute, University of Minnesota, Minneapolis, May 11-14, 2006; 7 pages, latex, World Scientific proceedings styl

Renormalization of Quantum Fields on the Lightcone Worldsheet I: Scalar Fields

We show that the lightcone worldsheet formalism, constructed to represent the sum of the bare planar diagrams of scalar \phi^3 field theory, survives the renormalization procedure in space-time dimensions D not greater than 6. Specifically this means that all the counter-terms, necessary to produce a successful renormalized perturbation expansion to all orders, can be represented as local terms in the lightcone worldsheet action. Because the worldsheet regulator breaks Lorentz invariance, we find the need for two non-covariant counter-terms, in addition to the usual mass, coupling and wave function renormalization. One of these can be simply interpreted as a rescaling of transverse coordinates with respect to longitudinal coordinates. The second one introduces couplings between the matter and ghost worldsheet fields on the boundaries.Comment: 18 pages, 3 figure