Three-body force in nuclear matter

We report calculations on the contribution of the three-body potential $W$ to the energy of nuclear matter which include realistic correlations in all internucleon distances which are consistent with realistic two-body potentials ($V$) in the calculation of the dominant second order [$〈V\left(\frac{Q}{e}\right)W〉$] contribution to the binding energy. For the Reid soft core potential we get a binding energy contribution of 6 MeV/nucleon. This is to be compared with the binding energy of 1.7 MeV/nucleon obtained using hard core potentials. The latter result is consistent with the calculations of Loiseau, Nogami, and Ross. The physical reason for the large difference between the results obtained from hard core and soft core two-body potentials is clarified.