Nuclear physics brought about by the π-mesons studied from field theory and experiments

In nuclei π-mesons are playing key role. At first the important interactions of π-mesons in light nuclei is explained mentioning that the π-meson exchange force is tensor force. It is pointed out that the importance of π-meson is observed even in the deuterons. By the progress of computations it is possible at present to calculate nuclei up to the mass number of twelve. It is explained then how to handle the π-mesons in heavy nuclei referring to the discovery of the halo of 11Li and its analysis. Due to the pseudo scalar properties of the π-mesons, tensor force is the strong nucleon-nucleon interaction. It has been necessary to go through numbers of trials and errors to arrive at the discovery of the proper tensor force analysis. It is shown to be possible to handle them in the Tensor-Optimized Shell Model (TOSM) based on the variation method. The explanation of the Extended Brueckner Hartree-Fock (EBHF) method obtained by combining the TOSM with the mean field theory used in the heavy nuclei is given. EBHF theory has the structure including high momentum components in the 2p2h wave functions. Calculated equation of state of symmetric nuclear matter is shown as a function of density in which important contribution of the tensor force is observed. Properties of nuclear matter are discussed. (S. Funahashi)