arXiv subjects

Ori J. Ganor

Publications and source records attributed to Ori J. Ganor.

48 records · Page 3Linked to original sources

arXiv1997

New Perspectives on Yang-Mills Theories With Sixteen Supersymmetries

We describe various approaches that give matrix descriptions of compactified NS five-branes. As a result, we obtain matrix models for Yang-Mills theories with sixteen supersymmetries in dimensions $2,3,4$ and 5. The equivalence of the various approaches relates the Coulomb branch of certain gauge theories to the moduli space of instantons on $T^4$. We also obtain an equivalence between certain six-dimensional string theories. Further, we discuss how various perturbative and non-perturbative features of these Yang-Mills theories appear in their matrix formulations. The matrix model for four-dimensional Yang-Mills is manifestly S-dual. In this case, we describe how electric fluxes, magnetic fluxes and the interaction between vector particles are realized in the matrix model.

hep-th↗

arXiv1997

Correlators of the Global Symmetry Currents of 4D and 6D Superconformal Theories

We study the two-point correlators of the currents of the $E_8$ global symmetry in the $N=(1,0)$ superconformal six-dimensional theory as well as in the 4D superconformal theories upon toroidal compactification. From the high-energy behavior of the correlator we deduce that in 4D 10 copies of the superconformal theory with $E_8$ global symmetry can be coupled to an N=2 $E_8$ gauge theory. We present three alternative derivations for the expression for the correlators. One from field-theory, one from M-theory and one from F-theory.

hep-th↗

arXiv1997

On The M(atrix)-Model For M-Theory On $T^6$

We study consistency conditions on a M(atrix)-model which would describe M-theory on $T^6$. We argue that there is a limit in moduli space for which it becomes a 6+1D theory and study the low-energy description of extended objects in the decompactified limit. We discuss the requirements from a M(atrix)-model which would describe such an $E_{6(6)}$ theory. We suggest that it could be a 5+1D theory and that a 1+1D theory with $(0,4)$ supersymmetry might be the M(atrix)-model for the M(atrix)-model of the $E_{6(6)}$ theory.

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arXiv1997

Higher Loop Effects in M(atrix) Orbifolds

Scattering of zero branes off the fixed point in $R^8/Z_2$, as described by a super-quantum mechanics with eight supercharges, displays some novel effects relevant to Matrix theory in non-compact backgrounds. The leading long distance behaviour of the moduli space metric receives no correction at one loop in Matrix theory, but does receive a correction at two loops. There are no contributions at higher loops. We explicitly calculate the two-loop term, finding a non-zero result. We find a discrepancy with M(atrix)-theory. Although the result has the right dependence on $v$ and $b$ for the scattering of zero branes off the fixed point the factors of $N$ do not match. We also discuss scattering in the orbifolds, $R^5/Z_2$ and $R^9/Z_2$ where we find the predicted fractional charges.

hep-th↗

arXiv1996

Branes, Fluxes and Duality in M(atrix)-Theory

We use the T-duality transformation which relates M-theory on T^3 to M-theory on a second T^3 with inverse volume to test the Banks-Fischler-Shenker-Susskind suggestion for the matrix model description of M-theory. We find evidence that T-duality is realized as S-duality for $U(\infty)$ N=4 Super-Yang-Mills in 3+1D. We argue that Kaluza Klein states of gravitons correspond to electric fluxes, wrapped membranes become magnetic fluxes and instantonic membranes are related to Yang-Mills instantons. The T-duality transformation of gravitons into wrapped membranes is interpreted as the duality between electric and magnetic fluxes. The identification of M-theory T-duality as SYM S-duality provides a natural framework for studying the M-theory 5-brane as the S-dual object to the unwrapped membrane. Using the equivalence between compactified M(atrix) theory and SYM, we find a natural candidate for a description of the light-cone 5-brane of M-theory directly in terms of matrix variables, analogous to the known description of the M(atrix) theory membrane.

hep-th↗

arXiv1996

A Note On Zeroes Of Superpotentials In F-Theory

We discuss the dependence of superpotential terms in 4D F-theory on moduli parameters. Two cases are studied: the dependence on world-filling 3-brane positions and the dependence on 2-form VEVs. In the first case there is a zero when the 3-brane hits the divisor responsible for the superpotential. In the second case, which has been extensively discussed by Witten in 3D M-theory, there is a zero for special values of 2-form VEVs when the M-theory divisor contains non-trivial 3-cycles. We give an alternative derivation of this fact for the special case of F-theory.

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arXiv1996

Branes, Calabi-Yau Spaces, and Toroidal Compactification of the N=1 Six-Dimensional E_8 Theory

We consider compactifications of the N=1, d=6, E_8 theory on tori to five, four, and three dimensions and learn about some properties of this theory. As a by-product we derive the SL(2,\IZ) duality of the N=2, d=4, SU(2) theory with N_f=4. Using this theory on a D-brane probe we shed new light on the singularities of F-theory compactifications to eight dimensions. As another application we consider compactifications of F-theory, M-theory and the IIA string on (singular) Calabi-Yau spaces where our theory appears in spacetime. Our viewpoint leads to a new perspective on the nature of the singularities in the moduli space and their spacetime interpretations. In particular, we have a universal understanding of how the singularities in the classical moduli space of Calabi--Yau spaces are modified by worldsheet instantons to singularities in the moduli space of the corresponding conformal field theories.

hep-th↗

arXiv1996

Toroidal Compactification of Heterotic 6D Non-Critical Strings Down to Four Dimensions

The low-energy limit of the 6D non-critical string theory with $N=1$ SUSY and $E_8$ chiral current algebra compactified on $T^2$ is generically an $N=2$ $U(1)$ vector multiplet. We study the analog of the Seiberg-Witten solution for the low-energy effective action as a function of $E_8$ Wilson lines on the compactified torus and the complex modulus of that torus. The moduli space includes regions where the Seiberg-Witten curves for $SU(2)$ QCD are recovered as well as regions where the newly discovered 4D theories with enhanced $E_{6,7,8}$ global symmetries appear.

hep-th↗

arXiv1996

Compactification of Tensionless String Theories

We study compactifications of the $N=2$ 6D tensionless string on various complex two-folds down to two-dimensions. In the IR limit they become non-trivial conformal field theories in 2D. Using results of Vafa and Witten on the partition functions of twisted Super-Yang-Mills theories, we can study the resulting CFT. We also discuss the contribution of instantons made by wrapping strings on 2-cycles of the complex two-fold.

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arXiv1996

A Test Of The Chiral E8 Current Algebra On A 6D Non-Critical String

Compactifying the $E_8$ non-critical string in 6D down to 5D the 6D strings give rise to particles and strings in 5D. Using the dual M-theory description compactified on an elliptically fibered Calabi-Yau we compare some of the 5D BPS states to what one expects from non-critical strings with an $E_8$ chiral current algebra. The $E_8$ multiplets of particle states comprise of 2-branes wrapping on irreducible curves together with bound states of several 2-branes.

hep-th↗

arXiv1996

Six-Dimensional Tensionless Strings In The Large N Limit

When $N$ five-branes of M-theory coincide the world-volume theory contains tensionless strings, according to Strominger's construction. This suggests a large $N$ limit of tensionless string theories. For the small $E_8$ instanton theories, the definition would be a large instanton number. An adiabatic argument suggests that in the large $N$ limit an effective extra uncompactified dimension might be observed. We also propose ``surface-equations'', which are an analog of Makeenko-Migdal loop-equations, and might describe correlators in the tensionless string theories. In these equations, the anti-self-dual two forms of 6D and the tensionless strings enter on an equal footing. Addition of strings with CFTs on their world-sheet is analogous to addition of matter in 4D QCD.

hep-th↗

arXiv1996

Small $E_8$ Instantons and Tensionless Non-critical Strings

T-duality is used to extract information on an instanton of zero size in the $E_8\times E_8$ heterotic string. We discuss the possibility of the appearance of a tensionless anti-self-dual non-critical string through an implementation of the mechanism suggested by Strominger of two coincident 5-branes. It is argued that when an instanton shrinks to zero size a tensionless non-critical string appears at the core of the instanton. It is further conjectured that appearance of tensionless strings in the spectrum leads to new phase transitions in six dimensions in much the same way as massless particles do in four dimensions.

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