A practical gauge invariant regularization of the SO(10) grand unified model

It is shown that a simple modification of the dimensional regularization allows to compute in a consistent and gauge invariant way any diagram with less than four loops in the SO(10) unified model. The method applies also to the Standard Model generated by the symmetry breaking SO(10)→SU(3)×SU(2)×U(1). A gauge invariant regularization for arbitrary diagram is also described.