Consequences of SU_3 Symmetry in Weak Interactions

These lectures will cover the relationship of SU_3 and the weak interactions. The lectures will be geared for experimental people so that they may get an idea of how our theoretical predictions arise. At first, I will speak a little bit about how calculations are made for the weak decays, then we shall consider SU_3 , and finally the effects of unitary symmetry upon the weak interactions. The subject matter is split in this way so that one may get a clearer idea of the origins of the various problems in the theory of weak interactions. Not all of our difficulties arise from SU, nor do all of the successes, and it is important to realize this. The theory of weak decays is very unsatisfactory except that it agrees with experiment. To understand that remark let us consider the muon. A muon is a particle which has exactly the same properties as the electron except that its mass is 207 times the mass of the electron. This statement completely describes our experiments with the muon, but such a comment is also unsatisfactory for a true theorist. Experimentalists find a beautiful and simple thing which is easy for the theorists to describe . Nevertheless, we must be unhappy about this situation because we have no idea of why this particle exists. Similarly, the theory of weak decay, up to the point where we encounter strangeness changing interact ions, is accurate but unsatisfactory. There are various mysterious properties which I shall mention as I go on, but I should like to remind you that the most mysterious aspect of the weak decays is that they exist at all. It seems so much simpler just to forget them. There is no clue from electromagnetism, from gravity, or from nuclear forces that the weak interactions must exist. They seem to have no connection with the rest of the world