Minimal standard heterotic string models

Abstract

Three generation heterotic-string vacua in the free fermionic formulation gave rise to models with solely the MSSM states in the observable Standard Model charged sector. The relation of these models to Z 2 × Z 2 orbifold compactifications dictates that they produce three pairs of untwisted Higgs multiplets. The reduction to one pair relies on the analysis of supersymmetric flat directions, that give superheavy mass to the dispensable Higgs states. We explore the removal of the extra Higgs representations by using the free fermion boundary conditions and hence directly at the string level, rather than in the effective low energy field theory. We present a general mechanism that achieves this reduction by using asymmetric boundary conditions between the left-and right-moving internal fermions. We incorporate this mechanism in explicit string models containing three twisted generations and a single untwisted Higgs doublet pair. We further demonstrate that an additional effect of the asymmetric boundary conditions is to substantially reduce the supersymmetric moduli

Niemeier Lattices in the Free Fermionic Heterotic–String Formulation

“…The heterotic-string models in the free fermionic formulation are among the most realistic string models constructed to date [31][32][33][34][35][36][37][38][39]. They correspond to 2 × 2 toroidal orbifold constructions at special points in the moduli space [49,[52][53][54][55][56][57].…”

“…The two-dimensional free fermions in the light-cone gauge (in the usual notation [28,29,[31][32][33][34][35][36][37][38][39] The class of models under investigation is generated by a maximal set of 7 basis vectors = {V 1 , V 2 , . .…”

Superstring Phenomenology

“…The Polyakov formalism allows us to make an important link with conformal field theory as follows. Note that (4.28) is unchanged by a Weyl transformation, 29) and so Weyl-equivalent metrics correspond to the same embedding in spacetime. The diff invariance allows the three degrees of freedom in γ ab to be replaced with just one; 30) where η ab = diag (−1, +1).…”

“…Therefore, the spinors |s form the so-called Dirac representation of the Lorentz algebra, and the ground states ψ µ 0 are seen to form a ten-dimensional spacetime fermion. Definining a ten-dimensional chirality operator, 29) PoS(cargese)001…”

Flux, gaugino condensation, and antibranes in heterotic M theory

“…Other groups are also making strides in heterotic model building, see for example [30][31][32][33][34][35].…”