Generic gravitational corrections to gauge couplings in SUSY SU(5) GUTs

We study non-universal corrections to the gauge couplings due to higher dimensional operators in supersymmetric SU(5) grand unified theories. The corrections are, in general, parametrized by three components originating from 24, 75 and 200 representations. We consider the prediction of α3(MZ) along each 24, 75 and 200 direction, and their linear combinations. The magnitude of GUT scale and its effects on proton decay are discussed. Non-SUSY case is also examined.