Three-nucleon force
Abstract
The expectation value of the two-pion-exchange three-body potential in the triton is estimated. The triton wave function is taken from a variational calculation with a hard-core two-nucleon potential. The effect of the (controversial) I = J = 0 dipion resonance (the σ-meson) is considered. The three-body potential consists of three parts: W = Wp + Ws + Wσ, where Wσ is due to the (virtual) π-N scattering via the σ-meson, while Wp and Ws are due respectively to the p-wave and s-wave π-N scattering via ``direct interactions''. The direct s-wave π-N interaction is set up so that, together with the π-N interaction via the σ-meson, it reproduces the observed s-wave π-N scattering length. Since it is rather meaningless to consider the two-pion-exchange potential alone at short distances, we introduce a cut-off distance d and set the three-body potential to be zero for distances less than d. The result is sensitive to d and also the hard-core raduis D of the two-body potential. For instance, for D = 0.4 fm, the contribution to the binding energy can be as big as about 1 MeV (attractive). Effects of the three-body force in nuclear matter are also discussed briefly.
Supported by the National Research Council of Canada.- Publication:
-
Nuclear Physics B
- Pub Date:
- August 1967
- DOI:
- 10.1016/0550-3213(67)90184-8
- Bibcode:
- 1967NuPhB...2..470L