Speaker
Description
We use the Covariant Spectator Theory (CST) to calculate the mass spectrum and relativistic vertex functions of mesons as quark-antiquark bound states in which at least one of the quarks is either a charm or bottom quark. The quark-antiquark bound-state equation in CST is, similar to the Bethe-Salpeter equation, an integral equation in which the kernel consists of two-particle irreducible Feynman diagrams. However, in the loop integration over intermediate four-momenta, only pole terms originated by the quark propagators are kept, which represent the leading contributions. This procedure leads to equations that possess the correct one-body limit, which is necessary for a realistic description of heavy-light systems. Our interaction kernel consists of a relativistic generalization of a linear confining potential, whose Lorentz structure is taken as an adjustable mixture of scalar, pseudoscalar, and vector form, and a one-gluon exchange interaction. I will present our recent results for fits to the observed meson spectrum and discuss the conclusions we can draw about the Lorentz structure of the quark-antiquark interaction.
