Excited baryons in the MIT bag model

The Johnson-Thorn bag model which explains the rotational motion of the elongated MIT bag is extended so as to describe the longitudinal vibration along the elongated bag. Our model is a kind of string model for baryons but it reduces to the ordinary spherical MIT bag model in the ground states. It is shown that the mass spectra of the P11 and P33 resonances of baryons can be reproduced by the present model as well as the Regge trajectories.