Nonminimal SU(5) model

The existence of the solution of the symmetry-breaking problem SU(5)→SU(3) ×SU(2)×U(1${)}_Y$→SU(3)×U(1${)}_Q$ is shown in a nonminimal model where the 75-dimensional Higgs field is used instead of the usual 24-dimensional one. The result is given in an explicit and simple form. The relevance of this solution to existing theories and to problems related to proton decay is discussed.