Cabibbo theory

It is interesting to note that whereas there are neutral currents amongst the Jj (e.g. J3 and Jg a,re both neutral) they play no role in the weak interactions in the Cabibbo theory. It will be seen later that there is now explicit evidence for neutral currents in weak interactions. 

Fig. 1.5. Quark level interaction responsible for /3-decay in Cabibbo theory.

Notice that in Cabibbo theory it is only the combination... 

The agreement between the predictions of Cabibbo theory and the data is generally very good for weak decays and for low energy scattering processes. A very detailed analysis of the situation can be found in Bailin (1982). Here we shall simply list some of the more spectacular successes of the theory. 

The above extension of the Cabibbo scheme is due to Kobayashi and Maskawa (1973). Because of the success of the Cabibbo theory it must be true that the new pieces in the mixtures which played a role earlier, must... 

Since the Cabibbo theory of weak interactions and its successor the SM gauge theory of weak and electromagnetic interactions are most simply formulated in terms of leptons and quarks, and since the low energy data are nicely consistent with this and a picture of the hadrons as built up from quarks, it would be most natural to expect that the point-like granules, the partons, discovered inside the hadrons, are in fact the quarks. Prom the point of view of hadron model building one tends to think of quarks as particles with a well-defined mass, whereas our partons have a continuous range of mass rrij = a mN(0 < a < 1). But, as mentioned earlier, the... 

As discussed in Section 9.2 the success of the Cabibbo theory implies that... 

One of the most interesting outcomes of gauge theory is the impossibility of making a reasonable model using just three quarks within the conventional Cabibbo current approach. Gauge theories require a larger group than SU(3) for hadrons. At the simplest level we require one new quark, the charm quark c. 

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