Departures from the Eightfold Way: Theory of Strong Interaction Symmetry Breakdown

Abstract

We consider the three kinds of departure from exact unitary symmetry: medium-strong interactions which leave only isospin and hypercharge as good symmetries, electromagnetism, and weak interactions. We postulate the existence of an octet of scalar mesons that give the possibility of symmetry-breaking tadpole diagrams. Our fundamental dynamical assumption—that symmetry-violating processes are dominated by symmetry-breaking tadpole diagrams—gives an immediate explanation of the success of two empirical laws: the Gell-Mann-Okubo mass formulas and the nonleptonic $\Delta I=\frac{1}{2}$ rules. Moreover, including tadpole diagrams and some other electromagnetic corrections, we calculate the six electromagnetic mass splittings of mesons and baryons in terms of a single unknown parameter correctly to within 0.5 MeV.