Fundamental Symmetries and Theory

Let me begin by thanking Bernard Frois and the Organizing Committee for making it possible for us to enjoy both the 1998 International Nuclear Physics Conference and the lovely city of Paris. My charge today is to summarize fundamental symmetries and theory, a topic with a rich history in nuclear physics. A generation ago nuclear studies of β decay helped established the V-A nature of the weak interaction, the conserved vector current hypothesis, and other aspects of the weak interaction that became part of the standard model’s experimental foundation. Much of the work carried on today is in searches for cracks in that foundation, subtle violations of low-energy symmetries that may indicate the nature of physics beyond the standard model. The field has become much too broad to cover adequately in one talk. Thus the best I can do this morning is to try to capture the flavor of the field by presenting four selected vignettes. Two of these — the discussions of hadronic parity violation and precision β decay experiments — focus primarily on the standard model. Two others — time reversal tests and massive neutrinos — look beyond the standard model to the new physics that we expect to characterize the next level of unification.