Medium corrections to the tensor interaction in nuclei: Energy difference of T=1 and T=0 J=0- states in 16O

It has been shown in the past that in a shell model calculation, restricted to 1Hbar*Omega 1p-1h configurations, the energy splitting between the lowest J=0-, T=0 and J=0-, T=1 states in 16O is mainly due to the tensor component of the nucleon-nucleon interaction. In this work, we extend the calculation to include 3Hbar*Omega 2p-2h and 3p-3h configurations. We use realistic G matrices derived from various One-Boson-Exchange potentials taking into account the effects of the Dirac-Brueckner-Hartree-Fock approach, i.e., a modification of the Dirac spinors for the nucleons in the medium. It is found that the splitting is rather sensitive to the long-range components of the isovector tensor force. The splitting is reduced considerably by including 2p-2h configurations, in particular.