Orbifold reduction of the quark-lepton symmetric model

We investigate the quark-lepton symmetric gauge group in five dimensions, with the gauge symmetry broken by a combination of orbifold compactification of the extra dimension and the Higgs mechanism. The gauge sector of the model is investigated and contrasted with the four dimensional case. We obtain lower bounds on the mass of the exotic gauge bosons, the inverse compactification scale and the exotic leptons. Light neutrinos are obtained without requiring any scale larger than a TeV. However an ultraviolet cutoff of order ${10}^{11}\mathrm{GeV}$ is required to suppress proton decay inducing nonrenormalizable operators.