6471453
Tachyon condensation on fuzzy sphere and noncommutative solitons
Abstract We study a brane–antibrane system and a non-BPS D-brane in SU(2) WZW model. We first discuss the tachyon condensation using the vertex operator formalism and find the generation of codimension two D-branes after the condensation. Our result is consistent with the recent interpretation that a D2-brane is a bound state of D0-branes. Then we investigate the world-volume effective theory on a non-BPS D-brane. It becomes a field theory on the “fuzzy sphere” when the level is sent to infinity. The most interesting feature is that there exist the noncommutative tachyonic solitons and we can identify them with D0-branes. We also discuss the brane–antibrane system from the world-volume point of view and comment on the relation to the noncommutative version of the index theorem.
119541412
Boundary states in Gepner models
We extend the construction of the boundary states in Gepner models to the non-diagonal modular invariant theories, and derive the same supersymmetric conditions as the diagonal theories. We also investigate the relation between the microscopic charges of the boundary states and Ramond charges of the B-type D-branes on the Calabi-Yau threefolds with one Kahler modulus in the large volume limit.
17506465
Singular Calabi-Yau manifolds and ADE classification of CFTS
Abstract We study superstring propagations on the Calabi–Yau manifold which develops an isolated ADE singularity. This theory has been conjectured to have a holographic dual description in terms of N=2 Landau–Ginzburg theory and Liouville theory. If the Landau–Ginzburg description precisely reflects the information of ADE singularity, the Landau–Ginzburg model of D 4 ,E 6 ,E 8 and Gepner model of A 2 ⊗A 2 ,A 2 ⊗A 3 ,A 2 ⊗A 4 should give the same result. We compute the elements of D 4 ,E 6 ,E 8 modular invariants for the singular Calabi–Yau compactification in terms of the spectral flow invariant orbits of the tensor product theories with the theta function which encodes the momentum mode of the Liouville theory. Furthermore we find the interesting identity among characters in minimal models at different levels. We give the complete proof for the identity.
16198184
Comments on D-branes in Kazama-Suzuki models and Landau-Ginzburg theories
We study D-branes in Kazama-Suzuki models by means of the boundary state description. We can identify the boundary states of Kazama-Suzuki models with the solitons in = 2 Landau-Ginzburg theories. We also propose a geometrical interpretation of the boundary states in Kazama-Suzuki models.
118695956
Spherical D2-brane from multiple D0-branes
We show that the spherical D2-brane in SU(2) WZW model can be well described as the “fuzzy sphere” configuration of D0-branes. We further investigate the stability of some configurations of D0-branes in NS5 background.
23166563
Notes on quantum entanglement of local operators
A bstractThis is an expanded version of the short report arXiv:1401.0539, where we studied the time evolution of (Renyi) entanglement entropies for the excited state defined by acting a given local operator on the ground state. In the present paper, we introduce (Renyi) entanglement entropies of given local operators which are defined by late time values of excesses of (Renyi) entanglement entropies. They measure the degrees of freedom of local operators and characterize them in conformal field theories from the viewpoint of quantum entanglement. We explain how to compute them in free massless scalar field theories and we also investigate their time evolution. Our results can be interpreted in terms of the relativistic propagation of entangled pairs. The main new results which we acquire in the present paper are as follows. Firstly, we provide an explanation which shows that (Renyi) entanglement entropies of a specific operator are given by (Renyi) entanglement entropies whose reduced density matrices are given by the binomial distribution. That operator is constructed of only the scalar field. Secondly, we found the sum rule which (Renyi) entanglement entropies of those local operators obey. Those local operators are located separately. Moreover we argue that (Renyi) entanglement entropies of specific operators in conformal field theories are given by (Renyi) entanglement entropies whose reduced density matrices are given by the binomial distribution. These specific operators are constructed of single-species operators. We also argue that general operators obey the sum rule which we mentioned above.