Higgs mass textures inflipped SU(5)

We analyze the Higgs doublet-triplet mass splitting problem in the version of nipped SU(5) derived from string theory. Analyzing non-renormalizable te rms up to tenth order in the superpotential, we identify a pattern of field vev's that keeps one pair of electroweak Higgs doublets light, while all o ther Higgs doublets and ail Higgs triplets are kept heavy, with the aid of the economical missing-doublet mechanism found in the field-theoretical ver sion of nipped SU(5). The solution predicts that second-generation charge - 1/3 quarks and charged leptons are much lighter than those in the third ge neration. (C) 1999 Elsevier Science B.V. All rights reserved.