Generalised magnetic monopole for the yang-mills field

By analogy to the magnetic monopole first proposed by Dirac (1931), a generalised magnetic monopole, being a source of the Yang-Mills field, is constructed. The gauge invariance and the rotational symmetry lead in a natural way to the quantisation not only of the electric charge but also of the hypercharge numberY. It is shown that the generalised magnetic charges are not arbitrary, and some restrictions on their values are deduced.