Closed String with Masses in Models of Baryons and Glueballs

The closed string carrying $n$ point-like masses is considered as the model of a baryon ($n=3$), a glueball ($n=2$ or 3) or another exotic hadron. For this system the rotational states are obtained and classified. They correspond to exact solutions of dynamical equations, describing an uniform rotation of the string with massive points. These rotational states result in a set of quasilinear Regge trajectories with different behavior. The stability problem for the so called central rotational states (with a mass at the rotational center) is solved with using the analysis of small disturbances. These states turned out to be unstable, if the central mass is less than some critical value.