arXiv subjects

V. Sadov

Publications and source records attributed to V. Sadov.

9 recordsLinked to original sources

arXiv1996

F-theory, Geometric Engineering and N=1 Dualities

We consider geometric engineering of N=1 supersymmetric QFTs with matter in terms of a local model for compactification of F-theory on Calabi-Yau fourfold. By bringing 3-branes near 7-branes we engineer N=1 supersymmetric $SU(N_c)$ gauge theory with $N_f$ flavors in the fundamental. We identify the Higgs branch of this system with the instanton moduli space on the compact four dimensional space of the 7-brane worldvolume. Moreover we show that the Euclidean 3-branes wrapped around the compact part of the 7-brane worldvolume can generate superpotential for $N_f=N_c-1$ as well as lead to quantum corrections to the moduli space for $N_f=N_c$. Finally we argue that Seiberg's duality for N=1 supersymmetric QCD may be mapped to T-duality exchanging 7-branes with 3-branes.

hep-th↗

arXiv1996

Geometric Singularities and Enhanced Gauge Symmetries

Using ``Tate's algorithm,'' we identify loci in the moduli of F-theory compactifications corresponding to enhanced gauge symmetry. We apply this to test the proposed F-theory/heterotic dualities in six dimensions. We recover the perturbative gauge symmetry enhancements of the heterotic side and the physics of small $SO(32)$ instantons, and discover new mixed perturbative/non-perturbative gauge symmetry enhancements. Upon further toroidal compactification to 4 dimensions, we derive the chain of Calabi-Yau threefolds dual to various Coulomb branches of heterotic strings.

hep-th↗

arXiv1995

D-Strings on D-Manifolds

We study the mechanism for appearance of massless solitons in type II string compactifications. We find that by combining $T$-duality with strong/weak duality of type IIB in 10 dimensions enhanced gauge symmetries and massless solitonic hypermultiplets encountered in Calabi-Yau compactifications can be studied perturbatively using D-strings (the strong/weak dual to type IIB string) compactified on ``D-manifolds''. In particular the nearly massless solitonic states of the type IIB compactifications correspond to elementary states of D-strings. As examples we consider the D-string description of enhanced gauge symmetries for type IIA string compactification on ALE spaces with $A_n$ singularities and type IIB on a class of singular Calabi-Yau threefolds. The class we study includes as a special case the conifold singularity in which case the perturbative spectrum of the D-string includes the expected massless hypermultiplet with degeneracy one.

hep-th↗

arXiv1995

D-Branes and Topological Field Theories

In the presence of a D-brane a string theory develops a new subsector. We show that for curved D-branes the corresponding sector is a (partially twisted) topological field theory. We use this result to compute the degeneracy of 2-branes wrapped around $K3$ cycles as well as 3-branes wrapped around CY threefold vanishing 3-cycles. In both cases we find the degeneracy is in accord with expectation. The counting of BPS states of a gas of 0-branes in the presence of a 4-brane in $K3$ is considered and it is noted that the effective 0-brane charge is shifted by 1, due to a quantum correction. This is in accord with string duality and the fact that left-moving ground state energy of heterotic string starts at $-1$. We also show that all the three different topological twistings of four dimensional $N=4$ Yang-Mills theory do arise from curved three-branes embedded in different spaces (Calabi-Yau manifolds and manifolds with exceptional holonomy groups).

hep-th↗

arXiv1995

Topological Reduction of 4D SYM to 2D $σ$--Models

By considering a (partial) topological twisting of supersymmetric Yang-Mills compactified on a 2d space with `t Hooft magnetic flux turned on we obtain a supersymmetric $σ$-model in 2 dimensions. For N=2 SYM this maps Donaldson observables on products of two Riemann surfaces to quantum cohomology ring of moduli space of flat connections on a Riemann surface. For N=4 SYM it maps $S$-duality to $T$-duality for $σ$-models on moduli space of solutions to Hitchin equations.

hep-th↗

arXiv1994

On equivalence of Floer's and quantum cohomology

(In the revised version the relevant aspect of noncompactness of the moduli of instantons is discussed. It is shown nonperturbatively that any BRST trivial deformation of A-model which does not change the ranks of BRST cohomology does not change the topological correlation functions either) We show that the Floer cohomology and quantum cohomology rings of the almost Kahler manifold M, both defined over the Novikov ring of the loop space LM of M, are isomorphic. We do it using a BRST trivial deformation of the topological A-model. As an example we compute the Floer = quantum cohomology of the 3-dimensional flag space Fl_3.

hep-th↗

arXiv1994

Quantum cohomology of partial flag manifolds

We compute the quantum cohomology rings of the partial flag manifolds F_{n_1\cdots n_k}=U(n)/(U(n_1)\times \cdots \times U(n_k)). The inductive computation uses the idea of Givental and Kim. Also we define a notion of the vertical quantum cohomology ring of the algebraic bundle. For the flag bundle F_{n_1\cdots n_k}(E) associated with the vector bundle E this ring is found.

hep-th↗

arXiv1993

The hamiltonian reduction of the BRST complex and N=2 SUSY

We study the nonunitary representations of N=2 Super Virasoro algebra for the rational central charges c<3. The resolutions for the irreducible representations of N=2 SVir in terms of the "2-d gravity modules" are obtained and their characters are computed. The correspondence between the N=2 nonunitary "minimal" models and the Virasoro minimal models coupled to 2-d gravity is shown at the level of states. We also define the hamiltonian reduction of the BRST complex of sl(N)/sl(N) coset to the BRST complex of the W-gravity coupled to the W matter. The case of sl(2) is considered explicitly. It leads to the presentation of N=2 Super Virasoro algebra by the Lie algebra cohomology. Finally, we reveal the mechanism of the correspondence between sl(2)/sl(2)$ coset and 2-d gravity.

hep-th↗

arXiv1993

Free field resolution for nonunitary representations of N=2 SuperVirasoro

We study N=2 SuperVirasoro SCFT for the generic value of the central charge. The main tool is the nonstandard bosonisation suggested in \ref\rRoz{L. Rozansky a letter to M. Bershadsky, 1989}, \ref\rSeBGR{B. Gato-Rivera, A. Semikhatov Phys. Letts. B293 (1992) 72},\ref\rBLNW{M. Bershadsky, W. Lerche, D. Nemeshansky, N. Warner N=2 Extended superconformal structure of Gravity and W Gravity coupled to Matter HUTP-A034/92}. The free field resolutions for the irreducible representations are obtained; the characters of these representations are computed. The quantum hamiltonian reduction from the Kac-Moody $\hat{sl}_k(2|1)$ to N=2 $SVir$ is constructed.

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