Grand Unified Theory on Interval −

We investigate a construction of five-dimensional (5D) grand unified theories (GUTs) on an interval, which we call iGUTs. We analyze supersymmetric SO(10) iGUT as an example, where the gauge multiplet is spread over the 5D bulk. The SO(10) is directly reduced to the standard model gauge symmetry through the interval boundary conditions. Notice that this rank reduction is impossible in case of GUTs on orbifolds. Four scenarios are possible according to locations (bulk or brane) of Higgs and matter fields. We also show a construction of interval boundary conditions by introducing non-dynamical Higgs fields on the brane and taking their vacuum expectation values to infinity. We show how spectra and boundary conditions of bulk fields change in this limit. Suitable SO(10)-breaking interval boundary conditions can be realized by this construction. Finally we comment on a model in a warped background setup.