相关论文: D-branes and the Standard Model

We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that…

We propose a mechanism for mediating supersymmetry breaking in Type I string constructions. The basic set-up consists of a system of three D-branes: two parallel D-branes, a matter D-brane and a source D-brane, with supersymmetry breaking…

We construct three flipped SU(5) X U(1)_X models from F-theory, and consider two such models from free fermionic string model building. To achieve the decoupling scenario in F-theory models and the string-scale gauge coupling unification in…

We use the boundary state formalism to study, from the closed string point of view, superpositions of branes and anti-branes which are relevant in some non-perturbative string dualities. Treating the tachyon instability of these systems as…

String compactifications with D-branes may exhibit regular magnetic monopole solutions, whose presence does not rely on broken non-abelian gauge symmetry. These stringy monopoles exist on interesting metastable brane configurations, such as…

An extension of the Standard Model to the local gauge group $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ which is a subgroup of the electroweak-strong unification group $E_6$ is analyzed. The mass scales, the gauge boson masses, and the masses…

We provide a general overview of the current state of the art in four dimensional three generation model building proposals - using intersecting D-brane toroidal compactifications [without fluxes] of IIA, IIB string theories - which have…

These lectures present some topics of string phenomenology and contain two parts. In the first part, I review the possibility of lowering the string scale in the TeV region, that provides a theoretical framework for solving the mass…

The product-group unification is a model of unified theories, in which masslessness of the two Higgs doublets and absence of dimension-five proton decay are guaranteed by a symmetry. It is based on SU(5) x U(N) (N=2,3) gauge group. It is…

We review the possibility that the Supersymmetric Standard Model arises from orbifold constructions of the E_8 x E_8 Heterotic Superstring, and the phenomenological properties that such a model should have. In particular, trying to solve…

We consider string phenomenological models based on 11D Horava-Witten M-theory with 5 branes in the bulk. If the 5-branes cluster close to the distant orbifold plane (d_n\equiv 1-z_n\simeq 0.1) and if the topological charges of the physical…

The appearance of a broken supersymmetric U(1) gauge factor at the TeV scale is relevant for several reasons. If it truly exists, then one important consequence is that at the 100 GeV energy scale, the two-doublet Higgs structure is of a…

We consider the type 0 theories, obtained from the closed NSR string by a diagonal GSO projection which excludes space-time fermions, and study the D-branes into these theories. The low-energy dynamics of N coincident D-branes is governed…

A TeV-scale scenario is constructed in an attempt to understand the relationship between quark and lepton masses. This scenario combines a model of early (TeV) unification of quarks and leptons with the physics of large extra dimensions. It…

Simple models are proposed where the baryon and lepton number are gauged and spontaneously broken near the weak scale. The models use a fourth generation that is vector-like with respect to the strong, weak and electromagnetic interactions…

A common way to obtain standard-model-like Lagrangians in string theory is to place D3-branes inside flux compactifications. The bosonic and fermionic masses and couplings of the resulting gauge theory are determined by the ten-dimensional…

We evaluate the tree level four fermion string amplitudes in the TeV string mass scale models with intersecting $D6$-branes. The coefficient functions of contact interactions subsuming the contributions of string Regge resonance and winding…

We construct a left-right symmetric model based on the gauge group $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ in five dimensions where both the gauge bosons and fermions reside in all five dimensions. The orbifold boundary conditions are used…

By employing D6-branes intersecting at angles in $D = 4$ type I strings, we construct {\em five stack} string GUT models (PS-II class), that contain at low energy {\em exactly the Standard model} with no extra matter and/or extra gauge…

We construct a top-mode standard model where the third generation fermions and the SU(2)_L \times U(1)_Y gauge bosons are put on a 6-dimensional brane(5-brane) with the extra dimensions compactified on the TeV scale(R_5^{-1}=R_6^{-1} \equiv…