Nuclear Physics with Electromagnetic Interactions

Abstract

As we have already discussed in Chaps. 2 and 3, a great deal of information about how protons and neutrons move inside the nucleus can be understood simply in terms of protons and neutrons interacting via an effective force inside the nuclear medium. Because of the presence of many other nucleons, this effective force deviates strongly from the corresponding force acting between free nucleons. However, a more fundamental theory would treat all medium effects explicitly, implying that, besides the pure nucleonic degrees of freedom, the mesonic degrees of freedom also start playing an important role. One should even take into account the various excited modes of the nucleons themselves. Eventually, the underlying building blocks of all matter involving the quark and gluon degrees of freedom will emerge in a description of how nucleons are built and, in a later step maybe, of how those composite particles (protons, neutrons) interact in an A-body nucleonic system. For most purposes though, as is clearly seen in the first three chapters, only effective forces and effective nucleons enter the description of the atomic nucleus. If one now wishes to find out at which energy (or length scale) particular new characteristics signaling the presence of mesons, excited nucleonic states and, even deeper, quark and gluon degrees of freedom actually emerge, one will need the appropriate microscope and a high enough energy to do so.