Strong interaction property of double Dirac string

We investigate the double Dirac string model for baryons proposed by Takabayashi. Explicit solutions to the wave equation for the double Dirac string are given. The elastic scattering amplitude of a nucleon and a pseudoscalar particle is calculated, the nucleon referring to the ground state of the string. Using the pseudoscalar coupling with the center-of-mass Dirac matrix, it is shown that the B amplitude has a pole-pole type duality, whereas the A amplitude vanishes identically. The imaginary part of the B amplitude has Regge asymptotics but the real one does not. A coupling scheme giving a non-vanishing A amplitude is also presented. (author)