Two-scale scalar mesons in nuclei
  We generalize the linear sigma model in order to develop a chiral-invariant model of nuclear structure. The model is natural, and contains not only the usual sigma meson which is the chiral partner of the pion but also a new chiral-singlet that is responsible for the medium-range nucleon-nucleon attraction. This approach provides significant advantages in terms of its description of nuclear matter and finite nuclei in comparison with conventional models based on the linear sigma model. 
K. Saito (1), H. Kouno (2), K. Tsushima (3), A.W. Thomas (4) ((1)   Department of Physics, Tokyo University of Science, Japa...