相关论文: Orientifolds, hypercharge embeddings and the Stand…

We show that for supersymmetric AdS vacua on Type IIA orientifolds with flux compactifications, the RR tadpole cancellation conditions can be completely relaxed, and then the four-dimensional N=1 supersymmetry conditions are the main…

Intersecting stacks of supersymmetric fractional branes on the Z_6' orientifold may be used to construct the supersymmetric Standard Model. If $a,b$ are the stacks that generate the SU(3)_{colour} and SU(2)_L gauge particles, then, in order…

We suggest SU(5)$'$ in the hidden sector toward a possible gauge mediated supersymmetry breaking scenario for removing the SUSY flavor problem, with an example constructed in $\Z_{12-I}$ with three families. The example we present has the…

Employing new scanning methods, we revisit the systematic construction of three-family $N=1$ supersymmetric Pati-Salam models in Type IIA orientifolds on ${\bf T}^6/(\mathbb Z_2\times \mathbb Z_2)$ with intersecting D6-branes. Arising from…

D6-branes intersecting at angles allow for phenomenologically appealing constructions of four dimensional string theory vacua. While it is straightforward to obtain non-supersymmetric realizations of the standard model, supersymmetric and…

In the context of supersymmetric compactifications of type II supergravity to four dimensions, we show that orientifold sources can be compatible with a generalized SU(3) x SU(3)-structure that is neither strictly SU(3) nor static SU(2). We…

We consider orientifold reductions to N=4 gauged supergravity in four dimensions. A special feature of this theory is that different factors of the gauge group can have relative angles with respect to the electro-magnetic SL(2) symmetry.…

We discuss the appearance of non-supersymmetric compactifications with exactly the Standard Model (SM) at low energies, in the context of IIB orientifold constructions with D5 branes intersecting at angles on the $T^4$ tori, of the…

We search for supersymmetric standard model realizations with extra singlets and extra $ U(1)$ using the heterotic string compactification on the $ Z_{6-II}$ orbifold with two Wilson lines. We analyze the vacuum restabilization mechanism…

In this talk we discus some properties of supersymmetric theories on orbifolds in five dimensions. The structure of FI--tadpoles may lead to (strong) localization of charged bulk scalars. Orbifold theories may suffer from various kinds of…

We provide a complete classification and statistical analysis of all type IIA orientifold compactifications with intersecting D6-branes on the orbifold T^6/Z'_6. The total number of four dimensional N=1 supersymmetric models is found to be…

We study the phenomenology of the strong-coupling limit of $E_8\times E_8$ heterotic string obtained from M-theory, using a Calabi-Yau compactification. After summarizing the standard embedding results, we concentrate on non-standard…

General features of the spectra of matter states in all 175 models found in a previous work by the author are discussed. Only twenty patterns of representations are found to occur. Accomodation of the Minimal Supersymmetric Standard Model…

We show that previous proposals to accommodate the MSSM with string theory N=0 non-supersymmetric compactifications coming from intersecting D6-branes may be made fully consistent with the cancellation of RR tadpoles. In this respect we…

We provide a systematic construction of three-family N=1 supersymmetric Pati-Salam models from Type IIA orientifolds on $\IT^6/(\IZ_2\times \IZ_2)$ with intersecting D6-branes. All the gauge symmetry factors $SU(4)_C\times SU(2)_L \times…

Supergravity solutions related to large N SU(N) pure gauge theories with eight supercharges have recently been shown to give rise to an ``enhancon'', a new type of hypersurface made of D-branes. We show that enhancons also arise in similar…

In tensor products of a left-right symmetric CFT, one can define permutation orientifolds by combining orientation reversal with involutive permutation symmetries. We construct the corresponding crosscap states in general rational CFTs and…

We study gauge symmetry breaking patterns of the five-dimensional $SU(5)$ grand gauge-Higgs unification compactified on an orbifold $S^1/{\mathbb Z}_2$ with the Hosotani mechanism in the framework of the diagonal embedding method. We find…

We construct new three-family ${\cal N}=1$ supersymmetric Pati-Salam models from intersecting D6-branes with original gauge group ${\rm U}(4)_C \times {\rm USp}(2)_L \times {\rm U}(2)_R$ on a Type IIA $\mathbb{T}^6/(\mathbb{Z}_2\times…

We explore the possibility of embedding the Pati-Salam model in the context of Type I brane models. We study a generic model with U(4)_C x U(2)_L x U(2)_R gauge symmetry and matter fields compatible with a Type I brane configuration.…