The role of chiral symmetry in two-pion exchange nuclear potential

We evaluate the two pion exchange contribution to the nucleon-nucleon potential in configuration space using a "minimal chiral model" containing only pions and nucleons. We argue that this model has nowadays a rather firm conceptual basis, which entitles it to become a standard ingredient of any modern potential. The main features of this model is that the scalar-isoscalar component of the interaction is relatively small, due to cancellations between large terms, and fails to reproduce the intermediate range attraction in the central channel. We show that chiral symmetry is the responsible for these large cancellations in the two-pion exchange nucleon-nucleon interaction, which are similar to those occuring in free pion-nucleon scattering. Another feature of the model is that these results do not depend on how chiral symmetry is implemented.