14351759
Fermionic Spectrum on General Dimensional Hyperdiamond Lattice
We have constructed general dimensional hyperdiamond lattices which are analogues of the three dimensional diamond lattice. Each site has the minimal number of bonds as possible in that dimension and the structure of the bond vectors is similar to that of the Clifford algebra. Furthermore, the spectrum zeros of the tight-binding hopping model on the hyperdiamond lattice are also investigated. The number of zeros is larger than two except for the two dimensional lattice, so that the minimal-doubling action cannot be realized on these lattices.
119324754
Duality and integrability of a supermatrix model with an external source
We study the Hermitian supermatrix model involving an external source. We derive the determinantal formula for the supermatrix partition function, and also for the expectation value of the characteristic polynomial ratio, which yields the duality between the characteristic polynomial and the external source with an arbitrary matrix potential function. We also show that the supermatrix integral satisfies the one and two dimensional Toda lattice equations as well as the ordinary matrix model.
7646194
Index theorem and overlap formalism with naive and minimally doubled fermions
We present a theoretical foundation for the Index theorem in naive and minimally doubled lattice fermions by studying the spectral flow of a Hermitean version of Dirac operators. We utilize the point splitting method to implement flavored mass terms, which play an important role in constructing proper Hermitean operators. We show the spectral flow correctly detects the index of the would-be zero modes which is determined by gauge field topology. Using the flavored mass terms, we present new types of overlap fermions from the naive fermion kernels, with a number of flavors that depends on the choice of the mass terms. We succeed to obtain a single-flavor naive overlap fermion which maintains hypercubic symmetry.
106401419
Phase structure of two-dimensional topological insulators by lattice strong-coupling expansion
The phase structure of 2-dimensional topological insulators under a sufficiently strong electron- electron interaction is investigated. The effective theory is constructed by extending the idea of the Kane-Mele model on the graphenelike honeycomb lattice, in terms of U(1) lattice gauge theory (quantum electrodynamics, QED). We analyze the phase structure by the techniques of strong coupling expansion of lattice gauge theory. As a result, we find that the topological phase structure of the system is modified by the electron-electron interaction. There evolves a new phase with the antiferromagnetism not parallel to the direction pointed by the spin-orbit coupling, in between the conventional and the topological insulator phases. We also discuss the physical implication of the new phase structure found here, in analogy to the parity-broken phase in lattice quantum chromodynamics (QCD), known as "Aoki phase".
117091130
Hall and spin Hall viscosity ratio in topological insulators
We study responses to metric perturbation in topological insulator models. In this paper we introduce a novel quantity, Hall viscosity to particle density ratio, which is analogous to the viscosity to entropy ratio suggested by AdS/CFT correspondence. This quantity corresponds to the filling fraction which characterizes the quantum Hall states, and hence it could be discussed in Haldane's zero-field quantum Hall system. We also consider dissipationless viscosity in the time reversal invariant quantum spin Hall system, which is related to a spin current.
55474215
Phase structure of topological insulators by lattice strong-coupling expansion
The effect of the strong electron correlation on the topological phase structure of 2-dimensional (2D) and 3D topological insulators is investigated, in terms of lattice gauge theory. The effective model for noninteracting system is constructed similarly to the lattice fermions with the Wilson term, corresponding to the spin-orbit coupling. Introducing the electron-electron interaction as the coupling to the gauge field, we analyze the behavior of emergent orders by the strong coupling expansion methods. We show that there appears a new phase with the in-plane antiferromagnetic order in the 2D topological insulator, which is similar to the so-called "Aoki phase" in lattice QCD with Wilson fermions. In the 3D case, on the other hand, there does not appear such a new phase, and the electron correlation results in the shift of the phase boundary between the topological phase and the normal phase.
10988502
Spectrum of eleven-dimensional supergravity on a pp -wave background
We calculate the spectrum of the linearized supergravity around the maximally supersymmetric pp-wave background in eleven dimensions. The resulting spectrum agrees with that of zero-mode Hamiltonian of a supermembrane theory on the pp-wave background. We also discuss the connection with the Kaluza-Klein zero modes of an ${\mathrm{AdS}}_{4}\ifmmode\times\else\texttimes\fi{}{\mathrm{S}}^{7}$ background.
118395821
Type IIA orientifolds and orbifolds on non-factorizable tori
Abstract We investigate type II orientifolds on non-factorizable torus with and without its oribifolding. We explicitly calculate the Ramond–Ramond tadpole from string one-loop amplitudes, and confirm that the consistent number of orientifold planes is directly derived from the Lefschetz fixed point theorem. We furthermore classify orientifolds on non-factorizable Z N × Z M orbifolds, and construct new supersymmetric type IIA orientifold models on them.
118497701
Chiral generations on intersecting 5-branes in heterotic string theory
We show that there exist two 27 and one $$ \bold{\overline {27}} $$ of E6, net one D = 4, $$ \mathcal{N} $$ = 1 chiral matter supermultiplet as zero modes localized on the intersection of two 5-branes in the E8 × E8 heterotic string theory. The smeared intersecting 5-brane solution is used via the standard embedding to construct a heterotic background, which provides, after a compactification of some of the transverse dimensions, a five-dimensional Randall-Sundrum II like brane-world set-up in heterotic string theory. As a by-product, we present a new proof of anomaly cancellation between those from the chiral matter and the anomaly inflow onto the brane without small instanton.
119125755
Chiral Zero Modes on intersecting Heterotic 5-branes
We show that there exist two 27 and one of E6, net one chiral supermultiplet as zero modes localized on the intersecting 5-branes in the E8 × E8 heterotic string theory. A heterotic background is constructed by the standard embedding in the smeared solution, and the Dirac equation is solved explicitly on this background. It provides, after the compactification of some of the transverse dimensions, an interesting five-dimensional brane-world set-up in heterotic string theory.
8177695
Gauged linear sigma models for noncompact Calabi-Yau varieties
Abstract We study gauged linear sigma models for noncompact Calabi–Yau manifolds described as a line bundle on a hypersurface in a projective space. This gauge theory has a unique phase if the Fayet–Iliopoulos parameter is positive, while there exist two distinct phases if the parameter is negative. We find four massless effective theories in the infrared limit, which are related to each other under the Calabi–Yau/Landau–Ginzburg correspondence and the topology change. In the T-dual theory, on the other hand, we obtain two types of exact massless effective theories: one is the sigma model on a newly obtained Calabi–Yau geometry as a mirror dual, while the other is given by a Landau–Ginzburg theory with a negative power term, indicating N = 2 superconformal field theory on SL ( 2 , R ) / U ( 1 ) . We argue that the effective theories in the original gauged linear sigma model are exactly realized as N = 2 Liouville theories coupled to well-defined Landau–Ginzburg minimal models.