arXiv subjects

Ori J. Ganor

Publications and source records attributed to Ori J. Ganor.

At least 37 records · Page 2Linked to original sources

arXiv2004

Twisted Six Dimensional Gauge Theories on Tori, Matrix Models, and Integrable Systems

We use the Dijkgraaf-Vafa technique to study massive vacua of 6D SU(N) SYM theories on tori with R-symmetry twists. One finds a matrix model living on the compactification torus with a genus 2 spectral curve. The Jacobian of this curve is closely related to a twisted four torus T in which the Seiberg-Witten curves of the theory are embedded. We also analyze R-symmetry twists in a bundle with nontrivial first Chern class which yields intrinsically 6D SUSY breaking and a novel matrix integral whose eigenvalues float in a sea of background charge. Next we analyze the underlying integrable system of the theory, whose phase space we show to be a system of N-1 points on $T$. We write down an explicit set of Poisson commuting Hamiltonians for this system for arbitrary N and use them to prove that equilibrium configurations with respect to all Hamiltonians correspond to points in moduli space where the Seiberg-Witten curve maximally degenerates to genus 2, thereby recovering the matrix model spectral curve. We also write down a conjecture for a dual set of Poisson commuting variables which could shed light on a particle-like interpretation of the system.

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arXiv2004

Noncommutative Dipole Field Theories And Unitarity

We extend the argument of Gomis and Mehen for violation of unitarity in field theories with space-time noncommutativity to dipole field theories. In dipole field theories with a timelike dipole vector, we present 1-loop amplitudes that violate the optical theorem. A quantum mechanical system with nonlocal potential of finite extent in time also shows violation of unitarity.

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arXiv2003

Twisted Backgrounds, PP-Waves and Nonlocal Field Theories

We study partially supersymmetric plane-wave like deformations of string theories and M-theory on brane backgrounds. These deformations are dual to nonlocal field theories. We calculate various expectation values of configurations of closed as well as open Wilson loops and Wilson surfaces in those theories. We also discuss the manifestation of the nonlocality structure in the supergravity backgrounds. A plane-wave like deformation of little string theory has also been studied.

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arXiv2002

Nonlocal Effects on D-branes in Plane-Wave Backgrounds

We argue that the effective field theory on D3-branes in a plane-wave background with 3-form flux is a nonlocal deformation of Yang-Mills theory. In the case of NSNS flux, it is a dipole field theory with lightlike dipole vectors. For an RR 3-form flux the dipole theory is strongly coupled. We propose a weakly coupled S-dual description for it. The S-dual description is local at any finite order in string perturbation theory but becomes nonlocal when all perturbation theory orders are summed together.

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arXiv2001

Nonlocal Field Theories and their Gravity Duals

The gravity duals of nonlocal field theories in the large N limit exhibit a novel behavior near the boundary. To explore this, we present and study the duals of dipole theories - a particular class of nonlocal theories with fundamental dipole fields. The nonlocal interactions are manifest in the metric of the gravity dual and type-0 string theories make a surprising appearance. We compare the situation to that in noncommutative SYM.

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arXiv2001

A Note on Intersecting and Fluctuating Solitons in 4D Noncommutative Field Theory

We examine the intersections, fluctuations and deformations of codimension two solitons in field theory on noncommutative $R^4$, in the limit of large noncommutativity. We find that holomorphic deformations are zero modes of flat branes, and we show that there is a zero mode localized at the intersection of two solitons.

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arXiv2000

New M(atrix)-models for Commutative and Noncommutative Gauge Theories

We propose a M(atrix) model for N=4 $SU(k)$ Super-Yang-Mills theory compactified on $T^4$. In this model it is possible to make $T^4$ noncommutative and it is easy to turn on all 6 components of the noncommutativity on $T^4$. The action of S-duality on the noncommutativity parameters is also manifest. The M(atrix)-model is given by the large $N$ limit of a $σ$-model on $T^2$ whose target space is the moduli space of $k$ SU(N) instantons on $T^3\times R$. We also propose that the $SU(k)$ 2+1D $Spin(8)$ theory (the low-energy description of $k$ M2-branes) on $T^3$ corresponds to the large $N$ limit of an integral over the latter instanton moduli space. The identification is based on the fact that Euclidean wrapped M2-branes in toroidally compactified M-theory correspond to instantons in the M(atrix)-model. In the new M(atrix) models, operators with nonzero momentum along $T^3$ (or $T^4$) correspond to insertions of Wilson lines along a 1-cycle that is determined by the momentum. Momentum is conserved in the large $N$ limit.

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arXiv2000

Constructions of Non Commutative Instantons on $T^4$ and $K_3$

We generalize the spectral-curve construction of moduli spaces of instantons on $\MT{4}$ and $K_3$ to noncommutative geometry. We argue that the spectral-curves should be constructed inside a twisted $\MT{4}$ or $K_3$ that is an elliptic fibration without a section. We demonstrate this explicitly for $T^4$ and to first order in the noncommutativity, for $K_3$. Physically, moduli spaces of noncommutative instantons appear as moduli spaces of theories with $\SUSY{4}$ supersymmetry in 2+1D. The spectral curves are related to Seiberg-Witten curves of theories with $\SUSY{2}$ in 3+1D. In particular, we argue that the moduli space of instantons of $U(q)$ Yang-Mills theories on a noncommutative $K_3$ is equivalent to the Coulomb branch of certain 2+1D theories with ${\cal N} = 4$ supersymmetry. The theories are obtained by compactifying the heterotic little-string theory on $T^3$ with global twists. This extends a previous result for noncommutative instantons on $\MT{4}$. We also briefly discuss the instanton equation on generic curved spaces.

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arXiv2000

Dipoles, Twists and Noncommutative Gauge Theory

T-duality of gauge theories on a noncommutative $T^d$ can be extended to include fields with twisted boundary conditions. The resulting T-dual theories contain novel nonlocal fields. These fields represent dipoles of constant magnitude. Several unique properties of field theories on noncommutative spaces have simpler counterparts in the dipole-theories.

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arXiv2000

Duality and Non-Commutative Gauge Theory

We study the generalization of S-duality to non-commutative gauge theories. For rank one theories, we obtain the leading terms of the dual theory by Legendre transforming the Lagrangian of the non-commutative theory expressed in terms of a commutative gauge field. The dual description is weakly coupled when the original theory is strongly coupled if we appropriately scale the non-commutativity parameter. However, the dual theory appears to be non-commutative in space-time when the original theory is non-commutative in space. This suggests that locality in time for non-commutative theories is an artifact of perturbation theory.

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arXiv2000

M(atrix)-Theory Scattering in the Noncommutative (2,0) theory

We study the Quantum-Mechanics on the hyper-Kahler manifold that is the blow-up of an $A_1$-singularity. This system is relevant for M(atrix)-theory as it was conjectured to describe scattering in the "noncommutative" deformation of a free 5+1D tensor multiplet in the sector with two units of longitudinal light-like momentum.

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arXiv2000

Pinned Branes and New Non Lorentz Invariant Theories

We describe a mechanism for localising branes in ambient space. When a 3-form flux is turned on in a Taub-NUT space, an M5-brane gets an effective potential that pins it to the center of the space. A similar effect occurs for M2-branes and D-branes with appropriate fluxes. In carefully chosen limits of the external parameters, this leads to new theories that are decoupled from gravity and appear to break Lorentz invariance. For example, we predict the existence of a new 5+1D theory that breaks Lorentz invariance at high-energy and has a low-energy description of N tensor multiplets with (1,0) supersymmetry. We also predict a new type of theory that, similarly to the little-string theory decouples from gravity by a dynamical (rather than kinematical) argument.

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arXiv2000

Chiral Compactifications of 6D Conformal Theories

We construct chiral N=1 gauge theories in 4D by compactifying the 6D Blum-Intriligator (1,0) theories of 5-branes at $A_k$ singularities on $T^2$ with a nontrivial bundle of the global U(1) symmetry of these theories.

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arXiv1999

Two Conjectures on Gauge Theories, Gravity, and Infinite Dimensional Kac-Moody Groups

We propose that the structure of gauge theories, the $(2,0)$ and little-string theories is encoded in a unique function on the real group manifold $E_{10}(R)$. The function is invariant under the maximal compact subgroup $K$ acting on the right and under the discrete U-duality subgroup $E_{10}(Z)$ on the left. The manifold $E_{10}(Z)\backslash E_{10}(R) /K$ contains an infinite number of periodic variables. The partition function of U(n), N=4 Super-Yang-Mills theory on $T^4$, with generic SO(6) R-symmetry twists, for example, is derived from the $n^{th}$ coefficient of the Fourier transform of the function with respect to appropriate periodic variables, setting other variables to the R-symmetry twists and the radii of $T^4$. In particular, the partition function of nonsupersymmetric Yang-Mills theory is a special case, obtained from the twisted $(2,0)$ or little-string theories. The function also seems to encode the answer to questions about M-theory on an arbitrary $T^8$. The second conjecture that we wish to propose is that this function is harmonic with respect to the $E_{10}(R)$ invariant metric. In a similar fashion, we propose that there exists a function on the infinite Kac-Moody group $DE_{18}$ that encodes the twisted partition functions of the $E_8$ 5+1D theories as well as answers to questions about the heterotic string on $T^7$.

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arXiv1999

Effects in Gauge Theories and a Harmonic Function on $E_{10}$

In a previous paper we conjectured that the structure of various gauge theories as well as M-theory on $T^8$ is encoded in a unique function $Ξ$ on the coset $E_{10}(Z)\backslash E_{10}(R)/K$ and that this function is harmonic with respect to the $E_{10}(R)$ invariant metric. In this paper we elaborate on the conjecture. We discuss various mass deformations of the D-instanton integral and their realizations in $Ξ$. We then present a conjectured prescription for extracting partition functions of the twisted little-string theory out of $Ξ$. We also study various effects of combinations of branes such as D0-branes near D4-branes with 2-form flux, D-instantons near Taub-NUT metrics, and more, in terms of harmonic functions on $E_d(R)/K$. We propose tests of the conjecture that are related to BPS states of global symmetries in gauge theories.

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arXiv1998

Instantons on a Non-commutative $T^4$ from Twisted (2,0) and Little-String Theories

We show that the moduli space of the $(2,0)$ and little-string theories compactified on $T^3$ with R-symmetry twists is equal to the moduli space of U(1) instantons on a non-commutative $T^4$. The moduli space of $U(q)$ instantons on a non-commutative $T^4$ is obtained from little-string theories of NS5-branes at $A_{q-1}$ singularities with twists. A large class of gauge theories with ${\cal N}=4$ SUSY in 2+1D and ${\cal N}=2$ SUSY in 3+1D are limiting cases of these theories. Hence, the moduli spaces of these gauge theories can be read off from the moduli spaces of instantons on non-commutative tori. We study the phase transitions in these theories and the action of T-duality. On the purely mathematical side, we give a prediction for the moduli space of 2 U(1) instantons on a non-commutative $T^4$.

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arXiv1998

U-duality Twists and Possible Phase Transitions in 2+1D Supergravity

We study 2+1D toroidal compactifications of M-theory with twists in the U-duality group. These compactifications realize many symmetric-manifolds from the classification of 2+1D extended supergravity moduli-spaces. We then focus on the moduli-space $SU(2,1)/U(2)$ obtained by dimensional reduction of pure N=2 supergravity in 3+1D. This space is realized with an explicit example. Assuming that there are no quantum corrections, we conjecture that the classical discrete duality group has to be augmented with an extra strong/weak coupling duality. This implies the existence of new phases of the theory in which the original 8 compactification radii are all fixed at the Planck scale.

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arXiv1998

On the Twisted (2,0) and Little-String Theories

We study the compactification of the $(2,0)$ and type-II little-string theories on $S^1$, $T^2$ and $T^3$ with an R-symmetry twist that preserves half the supersymmetry. We argue that it produces the same moduli spaces of vacua as compactification of the $(1,0)$ theory with $E_8$ Wilson lines given by a maximal embedding of SU(2). In certain limits, this reproduces the moduli space of SU(2) with a massive adjoint hyper-multiplet. In the type-II little-string theory case, we observe a peculiar phase transition where the strings condense. We conjecture a generalization to more than two 5-branes which involves instantons on non-commutative $T^4$. We conclude with open questions.

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