Microscopic reaction theory for direct nuclear reactions

Abstract:  Various aspects of nuclear physics, such as the properties of nuclear forces and the ground and excited states of nuclei, can be obtained through the analysis of nuclear reactions. Up to now, these were investigated with some reaction models based on phenomenological optical potentials, however, this approach has a limit to explore a new field of nuclear physics. On the contrary, it would not be possible to solve nuclear many-body problems starting from nuclear forces exactly even if we use a high performance computer. In fact, ab initio calculations are not available in most cases. According to multiple scattering theory, we can solve nuclear many-body problems efficiently by using an effective interaction instead of a bare nuclear force. The difficulty in handling the many-body effects is taken into account for the effective interaction. It should be noted that the effective interaction is constructed with a nuclear force, therefore, there is no ad hoc parameter in reaction calculations using the interaction. Recently, the microscopic description of various kinds of direct nuclear reactions based on an effective interaction is feasible. We show the recent progress of the microscopic reaction theory and the development of a new microscopic reaction theory starting from two- and three-nucleon forces based on chiral effective field theory.