Temporary Grand Unified Theory in Unphysical World

Abstract

We construct grand unified models on an orbifold based on unphysical grand unification. The reduction to the standard model or its supersymmetric one is carried out using a variant of Parisi-Sourlas mechanism and nontrivial $Z_2$ parity assignment.Comment: 10 pages, added appendix and typos corrected, proofread version to appear on Prog. Theor. Phy