arXiv subjects

Stanislav Kuperstein

Publications and source records attributed to Stanislav Kuperstein.

32 records · Page 2Linked to original sources

arXiv2009

ABJ(M) and Fractional M2's with Fractional M2 Charge

Recently Aharony, Bergman and Jafferis (ABJ) have argued that a 3d U(N+M)xU(N) Chern-Simons gauge theory at level (k,-k) may have a vacuum with N=6 supersymmetry only if M M(M-k)-1 with no restriction on the B-field. IIB brane cartoons and 11d supergravity solutions corresponding to N=3 vacua that do not preserve N=6 supersymmetry are argued to represent cascading gauge theories, generalizing the N=2 Seiberg duality conjectured by Giveon and Kutasov. While as usual the M2-brane charge runs as a result of the twisted Bianchi identity for *G_4, the M5-brane charge running relies on the fact that it wraps a torsion homology cycle.

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arXiv2009

Chiral Symmetry Breaking with non-SUSY D7-branes in ISD backgrounds

Supersymmetric probe branes satisfy the kappa-symmetry condition which ensures that the action is minimized with respect to both variations of the embedding and of the world-volume gauge field. We observe that the kappa-symmetry condition for a D7-brane in an imaginary self-dual (ISD) background can be generalized yielding minimization of the action with respect to variations of the gauge field only but not of the embedding. This provides a new way to construct non-BPS solutions for D7-branes once the embedding extremizes the geometrical volume of the brane. We then apply this method to the Klebanov-Strassler background and find a new D7-anti D7-brane configuration that realizes the spontaneous breaking of flavor chiral symmetry as evidenced by the Goldstone boson identified in the spectrum. This result generalizes our previous construction for the Klebanov-Witten model. We compare our setup with the Sakai-Sugimoto model and discuss possible applications to QCD-like physics.

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arXiv2009

A Comment on Kerr-CFT and Wald Entropy

We point out that the entropies of black holes in general diffeomorphism invariant theories, computed using the Kerr-CFT correspondence and the Wald formula (as implemented in the entropy function formalism), need not always agree. A simple way to illustrate this is to consider Einstein-Gauss-Bonnet gravity in four dimensions, where the Gauss-Bonnet term is topological. This means that the central charge of Kerr-CFT computed in the Barnich-Brandt-Compere formalism remains the same as in Einstein gravity, while the entropy computed using the entropy function gives a universal correction proportional to the Gauss-Bonnet coupling. We argue that at least in this example, the Kerr-CFT result is the physically reasonable one. The resolution to this discrepancy might lie in a better understanding of boundary terms.

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arXiv2009

Which BPS Baryons Minimize Volume?

A BPS 3-cycle in a Sasaki-Einstein 5-manifold in general does not minimize volume in its homology class, as we illustrate with several examples of non-minimal volume BPS cycles on the 5-manifolds Y(p,q). Instead they minimize the energy of a wrapping D-brane, extremizing a generalized calibration. We present this generalized calibration and demonstrate that it reproduces both the Born-Infeld and the Wess-Zumino parts of the D3-brane energy.

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arXiv2009

A New Holographic Model of Chiral Symmetry Breaking

A new family of models of flavour chiral symmetry breaking is proposed. The models are based on the embedding of a stack of D7-branes and a stack of anti D7-branes in the conifold background. This family of gravity models is dual to a field theory with spontaneous breaking of conformal invariance and chiral flavour symmetry. We identify the corresponding Goldstone bosons and compute the spectra of massive scalar and vector mesons. The dual quiver gauge theory is also discussed. We further analyse a model where chiral symmetry is not broken.

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arXiv2008

The Mesonic Branch of the Deformed Conifold

Using coordinates that manifest the S^2-S^3 split of the base, we study D3-branes localized on the three-sphere in the Klebanov-Strassler background. We find a numerical solution for the warp factor and show the emergence of the AdS throat near the stack. In the dual gauge theory, this corresponds to an RG flow along the mesonic branch. We demonstrate how the cubic superpotential of the N=4 SYM theory emerges at the end of the RG flow.

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arXiv2008

Gauge Theory RG Flows from a Warped Resolved Orbifold

We study gauge-string duality of D3-branes localized at a point on the resolution of the ALE orbifold $\IC^3/\IZ_3$. By explicitly solving for the warp factor, we demonstrate the holographic RG flow from $AdS_5 \times S^5/\IZ_3$ (far away from the resolution) to the usual $AdS_5\times S^5$ (close to the stack). On the gauge theory side, this maps to the flow between the quiver gauge theory and ${\cal N}=4$ super Yang-Mills. We present two possible scenarios for this RG flow depending on the choice of the VEVs. In particular, one of the scenarios proceeds by two steps involving both Higgsing and confinement.

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arXiv2008

Trivializing a Family of Sasaki-Einstein Spaces

We construct an explicit diffeomorphism between the Sasaki-Einstein spaces Y^{p,q} and the product space S^3 \times S^2 in the cases q \le 2. When q=1 we express the Kähler quotient coordinates as an SU(2) bundle over S^2 which we trivialize. When q=2 the quotient coordinates yield a non-trivial SO(3) bundle over S^2 with characteristic class p, which is rotated to a bundle with characteristic class 1 and re-expressed as Y^{2,1}, reducing the problem to the case q=1. When q>2 the fiber is a lens space which is not a Lie group, and this construction fails. We relate the S^2 \times S^3 coordinates to those for which the Sasaki-Einstein metric is known. We check that the RR flux on the S^3 is normalized in accordance with Gauss' law and use this normalization to determine the homology classes represented by the calibrated cycles. As a by-product of our discussion we find a diffeomorphism between T^{p,q} and Y^{p,q} spaces, which means that T^{p,q} manifolds are also topologically S^3 \times S^2.

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arXiv2007

Glueball operators and the microscopic approach to N=1 gauge theories

We explain how to generalize Nekrasov's microscopic approach to N=2 gauge theories to the N=1 case, focusing on the typical example of the U(N) theory with one adjoint chiral multiplet X and an arbitrary polynomial tree-level superpotential Tr W(X). We provide a detailed analysis of the generalized glueball operators and a non-perturbative discussion of the Dijkgraaf-Vafa matrix model and of the generalized Konishi anomaly equations. We compute in particular the non-trivial quantum corrections to the Virasoro operators and algebra that generate these equations. We have performed explicit calculations up to two instantons, that involve the next-to-leading order corrections in Nekrasov's Omega-background.

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arXiv2007

Cascading Quivers from Decaying D-branes

We use an argument analogous to that of Kachru, Pearson and Verlinde to argue that cascades in L^{a,b,c} quiver gauge theories always preserve the form of the quiver, and that all gauge groups drop at each step by the number M of fractional branes. In particular, we demonstrate that an NS5-brane that sweeps out the S^3 of the base of L^{a,b,c} destroys M D3-branes.

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arXiv2007

Trivializing and Orbifolding the Conifold's Base

The conifold is a cone over the space T^11, which is known to be topologically S^2xS^3. The coordinates used in the literature describe a sphere-bundle which can be proven to be topologically trivializable. We provide an explicit trivialization of this bundle, with simultaneous global coordinates for both spheres. Using this trivialization we are able to describe the topology of the base of several infinite families of chiral and non-chiral orbifolds of the conifold. We demonstrate that in each case the 2nd Betti number of the base matches the number of independent ranks in the dual quiver gauge theory.

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arXiv2006

On the pp-wave limit and the BMN structure of new Sasaki-Einstein spaces

We construct the pp-wave string associated with the Penrose limit of $Y^{p,q}$ and $L^{p,q,r}$ families of Sasaki-Einstein geometries. We identify in the dual quiver gauge theories the chiral and the non-chiral operators that correspond to the ground state and the first excited states. We present an explicit identification in a prototype model of $L^{1,7,3}$.

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arXiv2004

Analytic non-supersymmetric background dual of a confining gauge theory and the corresponding plane wave theory of Hadrons

We find a regular analytic 1st order deformation of the Klebanov-Strassler background. From the dual gauge theory point of view the deformation describes supersymmetry soft breaking gaugino mass terms. We calculate the difference in vacuum energies between the supersymmetric and the non-supersymmetric solutions and find that it matches the field theory prediction. We also discuss the breaking of the $U(1)_R$ symmetry and the space-time dependence of the gaugino bilinears two point function. Finally, we determine the Penrose limit of the non-supersymmetric background and write down the corresponding plane wave string theory. This string describes ``annulons''-heavy hadrons with mass proportional to large global charge. Surprisingly the string spectrum has two fermionic zero modes. This implies that the sector in the non-supersymmetric gauge theory which is the dual of the annulons is supersymmetric.

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arXiv2004

Non-critical supergravity (d>1) and holography

In this paper we investigate the supergravity equations of motion associated with non-critical ($d>1$) type II string theories that incorporate RR forms. Using a superpotential formalism we determine several classes of solutions. In particular we find analytic backgrounds with a structure of $AdS_{p+2}\times S^{d-p-2}$ and numerical solutions that asymptote a linear dilaton with a topology of $R^{1,d-3}\times R \times S^1$. The SUGRA solutions we have found can serve as anti holographic descriptions of gauge theories in a large $N$ limit which is different than the one of the critical gauge/gravity duality. It is characterized by $N\rt \infty$ and $g_{YM}^2 N \sim 1$. We have made the first steps in analyzing the corresponding gauge theory properties like Wilson loops and the glue-ball spectra.

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