Constructing 5d orbifold grand unified theories from heterotic strings

Abstract

A three-generation Pati-Salam model is constructed by compactifying the heterotic string on a particular T^6/Z_6 Abelian symmetric orbifold with two discrete Wilson lines. The compactified space is taken to be the Lie algebra lattice G_2+SU(3)+SO(4). When one dimension of the SO(4) lattice is large compared to the string scale, this model reproduces many features of a 5d SO(10) grand unified theory compactified on an S^1/Z_2 orbifold. (Of course, with two large extra dimensions we can obtain a 6d SO(10) grand unified theory.) We identify the orbifold parities and other ingredients of the orbifold grand unified theories in the string model. Our construction provides a UV completion of orbifold grand unified theories, and gives new insights into both field theoretical and string theoretical constructions.Comment: 15 pages, 3 figures, 1 table, revtex

Proton hexality in local grand unification

“…(For a discussion within the context of heterotic orbifolds, see e.g. [35].) In our bottom-up approach we pick the phases by hand.…”

Flavour Structure and Proton Decay in 6D Orbifold GUTs

“…This kind of model can naturally arise in compactifications of the heterotic string [26,27]. Quark and lepton mass matrices are approximately of lopsided type, with some characteristic modifications compared to the 4D lopsided picture.…”

Stringy origin of non-Abelian discrete flavor symmetries

“…The selection rules for heterotic orbifolds are well known [14,15,16], but little attention has been paid to the emerging non-Abelian flavor symmetries. Recently, explicit string compactifications, based on the 6 −II = 2 × 3 heterotic orbifold, with a D 4 flavor symmetry have been constructed [17,18,19,20]. In these models, the three generations are comprised of a singlet and a doublet under the D 4 symmetry.…”