O(5)xU(1) electro weak gauge theory and the triggering of the Cabbibo-rotation by 't Hooft-Polyakov monopole

The present study is based on the O(5)xU(1) ElectroWeak gauge theory with the two particle generations of quarks. With the spontaneously symmetry breaking down to the O(3) level the 't Hooft-Polyakov SO(3) monopole theory along with its triplet of scalar fields is reproduced and developed to the extent necessary to establish our results. It is shown that the existence of the monopole triggers the Cabibbo rotation of d and s flavours. It is exactly the Cabibbo angle in which the isovector φ-bar has to be rotated so as to spontaneously break the symmetry down to the O(3) level, together with, on the SO(3) sector to the U(1) level. As a byproduct it turns out that the Weinberg angle is twice the Cabbibo angle, a result already noted by the author elsewhere. (author). 17 refs