Mesons in the relativistic flux tube model

The relativistic flux tube model is used to describe the spectra of all mesons, including the pseudoscalar light nonet. Quite good results are obtained, provided the flux tube is supplemented by a Coulomb-like potential, an interaction inspired from instanton effects, and a negative constant energy. Three different procedures to introduce this constant are compared, and two different Ansätze are tested to simulate the asymptotic freedom phenomenon. A matix method to solve the coupled nonlinear equations of the asymmetric flux tube is presented.