2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/176528We consider the gauge coupling running in a six-dimensional SO(10) orbifold GUT model. The bulk gauge symmetry is broken down to the standard model gauge group with an extra U(1)_X by orbifold boundary conditions and the extra U(1)_X is further broken through the U(1)_{B-L} breaking with bulk hyper multiplets. We obtain the corrections of Kaluza-Klein massive modes to the running of the gauge couplings and discuss their implication to the successful gauge coupling unification.10 pages, 2 figures, version to appear in Physics Letters BHigh Energy Physics - PhenomenologyHigh Energy Physics - Theorytext