On the study of quark confinement and quantum chromodynamics string

The scalar potential, time component vector potential and flux tube quark confinements are studied. The concept of Lorentz scalar quark confinement has a long history and is still widely used despite its well-known theoretical faults. We point out here that the predictions of scalar confinement also conflict directly with experiment. We investigate the dependence of heavy-light meson mass differences on the mass of the light quark. In particular, we examine the strange and non-strange D mesons. We find that the predictions of scalar confinement and time component vector confinement are in considerable conflict with measured values while the flux tube confinement works well to explain the experimental data. For the relativistic flux tube model, from the comparison of exact numerical solution with the analytic approximation solution for both heavy-light and light-light mesons, we see that they are much more in agreement with each other for higher excited states since the deep radial limit is better satisfied. The relativistic flux tube model gives the correct universal relations between the heavy-light and light-light meson spectroscopies.