相关论文: Can String Theory Predict the Weinberg Angle?

Three family SU(3)_C x SU(2)_L x U(1)_Y string models in several constructions generically possess two features: (i) an extra local anomalous U(1)_A and (ii) numerous (often fractionally charged) exotic particles beyond those in the minimal…

Using the bosonic supercurrent (or covariant lattice) formalism, we review how to compute scattering amplitudes in asymmetric orbifold string models. This method is particularly useful for calculating scattering of multiple asymmetrically…

We present a class of heterotic compactifications where it is possible to lower the string unification scale down to the GUT scale, while preserving the validity of the perturbative analysis. We illustrate this approach with an explicit…

We discuss a heterotic-string solution in which the observable sector effective field theory just below the string scale reduces to that of the MSSM, with the standard observable gauge group being just SU(3)_C x SU(2)_L x U(1)_Y and the…

By representing the electroweak gauge symmetry group $SU(2) \times U(1)$ by a hypertorus $S_2 \times S_1$, the electroweak mixing angle and the fine structure constant are predicted. By representing neutrinos as oscillating spheroid…

We discuss the possible applications supersymmetric theories might find in the field of elementary particle physics. The supersymmetric generalization of the $SU(3)\times SU(2)\times U(1)$ standard model is discussed in detail. Special…

What symmetry breaking would be required for gauginos from a supersymmetric theory to behave like left-handed quarks of the Standard Model? Starting with a supersymmetric SU(3)xSU(3)xU(1)xU(1) gauge theory, the 18 adjoint-representation…

We obtain three generation SU(3)_c X SU(2)_L X U(1)_Y string models in all of the exactly solvable (0,2) constructions sampled by fermionization. None of these examples, including those that are symmetric abelian orbifolds, rely on the Z_2…

We approach the following question: if supersymmetry is discovered, how can we select among different supersymmetric extensions of the Standard Model? In particular, we perform an analysis of the sparticle spectrum in low-energy string…

Higher dimensional grand unified theories, with gauge symmetry breaking by orbifold compactification, possess SU(5) breaking at fixed points, and do not automatically lead to tree-level gauge coupling unification. A new framework is…

In the superstring models we have not only the complete {\bf 27} multiplets of $E_6$ but also extra incomplete $({\bf 27}+{\overline {\bf 27}})$ chiral supermultiplets being alive at low energies. Associated with these additional…

Using the current precision electroweak data, we look for the minimal particle content which is necessary to add to the standard model in order to have a complete unification of gauge couplings and gravity at the weakly coupled heterotic…

The genus-dependence of multi-loop superstring amplitudes is bounded at large orders in perturbation theory using the super-Schottky group parametrization of supermoduli space. Partial estimates of supermoduli space integrals suggest an…

We explain the orbifold compactification in string models and present a Z_{12-I} orbifold compactification toward supersymmetric standard models. We also point out an effective R-parity from this string construction. The VEVs of gauge…

The recent conjecture of possible equivalence between the string scale $M_S$ and the minimal supersymmetric standard model unification scale M_U ~ 2.5 x 10^{16} GeV is considered in the context of string models. This conjecture suggests…

Recent string constructions with intersecting D6 and D5 brane models succeeded in predicting in the low energy limit a symmetry group and a fermionic spectrum similar to that of the SM. In such constructions additional U(1) fields are a…

We introduce a class of (0,2) superconformal field theories based on hybrid geometries, generalizing various known constructions. We develop techniques for the computation of the complete massless spectrum when the theory can be interpreted…

We consider the possibility of grand unification of the $\mathrm{ SU(3)_c \otimes SU(3)_L \otimes U(1)_X}$ model in an SU(6) gauge unification group. Two possibilities arise. Unlike other conventional grand unified theories, in SU(6) one…

We review efforts in string model building, focusing on the heterotic orbifold compactifications. We survey how one can, starting from an explicit string theory, obtain models which resemble Nature. These models exhibit the standard model…

I review findings of various research groups regarding perturbative heterotic string model building in the last 12 months. Attention is given to recent studies of extra U(1)'s and local discrete symmetries (LDS's) in generic string models.…