Chiral Symmetry and the Nucleon-Nucleon Interaction

The main progress in the eld of nucleon-nucleon (NN) potentials, which we have seen in recent years, is the construction of some very quantitative (high-quality/high-precision) NN potentials. These potentials will serve as excellent input for microscopic nuclear structure calculations and will allow for a systematic investigation of o -shell effects. After this enormous quantitative work, it is now time to re-think the NN problem in fundamental terms. We need a derivation of the nuclear force which observes Lorentz invariance and the symmetries of QCD. Current Status of NN Potentials The New High-Precision NN Potentials. In 1993, the Nijmegen group published a phase-shift analysis of all proton-proton and neutron-proton data below 350 MeV lab. energy with a 2 per datum of 0.99 for 4301 data [1]. Based upon this analysis, charge-dependent NN potentials have been constructed by the Nijmegen [2], the Argonne [3], and the Bonn (CD-Bonn [4]) groups which reproduce the NN data with a /datum 1 (see Table 1). The main di erence between these new potentials is that some are local and some non-local. Ever since NN potentials have been developed, local potentials have enjoyed great popularity because they are easy to apply in con guration-space calculations. Note, however, that numerical ease is not a proof for the local Invited Talk presented at the XIII International Seminar on High Energy Physics Problems at the Joint Institute for Nuclear Research, Dubna (Russia), September 2-7, 1996. e-mail address: [email protected]