String MSSM through flipped SU(5) from Z_{12} orbifold
arXiv:hep-th/0608085
Abstract
In a orbifold compactification through an intermediate flipped SU(5), the string MSSM (MSSM) spectra (three families, one pair of Higgs doublets, and neutral singlets) are obtained with the Yukawa coupling structure. The GUT , even with exotics in the twisted sector, can be run to the observed electroweak scale value by mass parameters of vectorlike exotics near the GUT scale. We also obtain R-parity and doublet-triplet splitting.
5 pages