Roper resonance in the relativistic three-quark model
  The relativistic three-quark equations are found in the framework of the dispersion relation technique. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitude are obtained. The calculated mass values of two ($ N=2, 56^* $) baryonic multiplets $ J^P ={{1/2}}^{+},{{3/2}}^{+} $ are in good agreement with the experimental ones. 
D.V. Ivanov