Abstract
Taking into account the relativistic and nonlocal character of interactions, the mass spectrum of mesons consisting of light-light and light-heavy quarks with orbital and radial excitations is determined. Our results show that good agreement with the experimental data for the slope and the intercept of the Regge trajectory can be obtained only by taking into account the nonperturbative and the nonlocal character of interactions. There is certainly a dependence of the constituent mass of constituent particles on the mass of a free state. When quarks are light, the difference in current and valent masses of quarks is greater than in valent masses of quarks; when quarks are heavy, the difference in theses masses is insignificant. One alternative version of the account of nonlocality is suggested for a definition of the properties of hadrons at large distances. The dependence of constituent mass on the radius of confinement is studied.