Three-Nucleon Interaction

A contribution to the long-range part of the three-nucleon potential arising from the interaction of virtual pions with the cloud of $s$-wave, two-pion resonances around a nucleon is investigated. Crude estimates are made for the effect of this potential in nuclear matter and in the triton. In nuclear matter the corresponding effective two-nucleon interaction at small distances is repulsive and strong enough to dominate the one-pion-exchange potential. The contribution to the triton binding energy is about 1.1 MeV.