Related papers: Anomaly-Free Supersymmetric Models in Six Dimensio…
We carry a systematic study of possible extensions of the standard model based on the gauge group SU(3)_c X SU(4)_L X U(1)_X. We consider both models with particles with exotic electric charges and models which do not contain exotic…
In string theory, there are no continuous global symmetries. Discrete symmetries frequently appear, and these can often be understood as unbroken subgroups of larger, spontaneously broken gauge symmetries (discrete gauge symmetries). In…
We revisit the relation between the anomalies in four and six dimensions and the Chern-Simons couplings one dimension below. While the dimensional reduction of chiral theories is well-understood, the question which three and…
We study dynamical gauge symmetry breaking via compactified space in the framework of SU(N) gauge theory in M^{d-1}\times S^1 (d=4,5,6) space-time. In particular, we study in detail the gauge symmetry breaking in SU(2) and SU(3) gauge…
We present an orbifold compactification of the minimal seven dimensional supergravity. The vacuum is a slice of AdS_7 where six-branes of opposite tension are located at the orbifold fixed points. The cancellation of gauge and gravitational…
We discuss the construction of four dimensional non-supersymmetric models obtained from configurations of D6-branes intersecting at angles. We present the first examples of string GUT models which break exactly to the Standard Model (SM) at…
We consider the multi-instanton collective coordinate integration measure in N=2 supersymmetric SU(N) gauge theory with N_F fundamental hypermultiplets. In the large-N limit, at the superconformal point where N_F=2N and all VEVs are turned…
We argue for the existence of additional constraints on SU(2) gauge theories in four dimensions when realized in ultraviolet completions admitting an analog of D-brane nucleation. In type II string compactifications these constraints are…
In a minimal extension of the Standard Model, in which new neutral fermions have been introduced, we show that the requirement of vanishing anomalies fixes the hypercharges of all fermions uniquely. This naturally leads to electric charge…
We construct a seven-dimensional brane world in a slice of AdS_7, where the boundary matter content is fixed by the cancellation of anomalies. The seven-dimensional minimal N=2 gauged supergravity is compactified on the orbifold S^1/Z_2,…
Anomalies can be elegantly analyzed by means of the Dai-Freed theorem. In this framework it is natural to consider a refinement of traditional anomaly cancellation conditions, which sometimes leads to nontrivial extra constraints in the…
We discuss anomaly cancellation in $U(2)$ gauge theories in four dimensions. For a $U(2)$ gauge theory defined with a spin structure, the vanishing of the bordism group $\Omega_5^{\text{Spin}}(BU(2))$ implies that there can be no global…
We examine SL(2, Z) anomalies in ten and eight-dimensional supergravities, the induced local counterterms and their realization in string theory. Composite connections play an important role in the cancellation mechanism. At the same time…
Compactified string theories give rise to discrete symmetries which are essential if they are to provide a realistic low energy theory. We find that in a class of four dimensional string theories these symmetries are constrained by similar…
An interesting family gauge boson (FGB) model (Model A) has been proposed by Sumino. The model can give FGBs with a considerably low energy scale in spite of the sever constraints form the observed $K^0$-$\bar{K}^0$ mixing and so on. An…
We reexamine the question of quantum consistency of supergravities in eight dimensions. Theories with 16 supercharges suffer from the anomalies under the action of its discrete modular groups. In minimally supersymmetric theory coupled to…
We delineate a procedure to classify 6d N=(1,0) gauge theories composed, in part, of a semi-simple gauge group and hypermultiplets. We classify these theories by requiring that they satisfy some consistency conditions. The primary…
We discuss local \R-symmetry as a potentially powerful new model building tool. We first review and clarify that a $U(1)$ \R-symmetry can only be gauged in local and not in global supersymmetry. We determine the anomaly-cancellation…
We study a number of supersymmetric solutions in the form of $Mkw_3\times S^3$- and $AdS_3\times S^3$-sliced domain walls in the maximal gauged supergravity in seven dimensions. These solutions require non-vanishing three-form fluxes to…
We show that the heterotic supersymmetry (Killing spinor equations) and the anomaly cancellation imply the heterotic equations of motion in dimensions five, six, seven, eight if and only if the connection on the tangent bundle is an…