Effect of the Baryon Excited States on theN−ΛandΛ−ΛForces

The $N-\Lambda$ and $\Lambda -\Lambda$ potentials caused by the exchange of two pions are calculated in the static theory, taking into account the resonance ${Y_1}^{*}$ in the $\pi -\Lambda$ system and the (3-3) resonance in the $\pi -N$ system. The recoil of the baryons is included in an approximate way. It is shown that the presence of these resonances diminishes the spin-dependent part of the central potential and the tensor potential, and increases the spin-independent part of the central potential. The triplet potential turns out to be slightly stronger than the singlet potential at large distances, and slightly weaker than it closer in. If the resonances are omitted, the triplet potential is the stronger over the whole range. This last result is in mild disagreement with other work. Its relation to the choice of a one-channel or two-channel formalism is discussed.