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Sep 18, 2013
09/13

by
M. Porrati

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In this review, we summarize recent findings that show how standard 4-d Einstein gravity coupled to a conformal field theory can become massive in Anti de Sitter Space. Key ingredients in this phenomenon are non-standard ``transparent'' boundary condition given to the CFT fields and the fact that AdS space is not globally hyperbolic, due to the presence of a time-like boundary.

Source: http://arxiv.org/abs/hep-th/0306253v2

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Sep 21, 2013
09/13

by
M. Porrati

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Modifications to the primordial power spectrum of inflationary density perturbations have been studied recently using a boundary effective field theory approach. In the approximation of a fluctuating quantum field on a fixed background, the generic effect of new physics is encoded in parameters of order H/M. Here, we point out that the back-reaction on the metric can be neglected only when these parameters obey certain bounds that may put them beyond the reach of observation.

Source: http://arxiv.org/abs/hep-th/0402038v2

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Sep 18, 2013
09/13

by
M. Porrati

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We review model independent arguments showing that massless particles interacting with gravity in a Minkowski background space can have at most spin two. These arguments include a classic theorem due to Weinberg, as well as a more recent extension of the Weinberg-Witten theorem. A puzzle arising from an apparent counterexample to these theorems is examined and resolved.

Source: http://arxiv.org/abs/1209.4876v2

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Sep 21, 2013
09/13

by
M. Porrati

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We review the "no-go" theorems that severely constrain the breaking of N=2 supersymmetry to N=1 (both in rigid supersymmetry and supergravity), and we exhibit some models that evade them.

Source: http://arxiv.org/abs/hep-th/9609073v1

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Jul 20, 2013
07/13

by
M. Porrati

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We present a model-independent argument showing that massless particles interacting with gravity in a Minkowski background space can have at most spin two. This result is proven by extending a famous theorem due to Weinberg and Witten to theories that do not possess a gauge-invariant stress-energy tensor.

Source: http://arxiv.org/abs/0804.4672v3

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Sep 21, 2013
09/13

by
M. Porrati

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In both old and recent literature, it has been argued that the celebrated van Dam-Veltman-Zakharov (vDVZ) discontinuity of massive gravity is an artifact due to linearization of the true equations of motion. In this letter, we investigate that claim. First, we exhibit an explicit -albeit somewhat arbitrary- fully covariant set of equations of motion that, upon linearization, reduce to the standard Pauli-Fierz equations. We show that the vDVZ discontinuity still persists in that non-linear,...

Source: http://arxiv.org/abs/hep-th/0203014v2

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Sep 22, 2013
09/13

by
M. Porrati

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I review some interesting features of massive gravity in two maximally symmetric backgrounds: Anti de Sitter space and Minkowski space. While massive gravity in AdS can be seen as a spontaneously broken, UV safe theory, no such interpretation exists yet in the flat-space case. Here, I point out the problems encountered in trying to find such completion, and possible mechanisms to overcome them.

Source: http://arxiv.org/abs/hep-th/0409172v1

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Sep 22, 2013
09/13

by
M. Porrati

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We prove that the van Dam-Veltman-Zakharov discontinuity arising in the massless limit of massive gravity theories is peculiar to Minkowski space and it is not present in Anti De Sitter space, where the massless limit is smooth. More generally, the massless limit is smooth whenever the square of the graviton mass vanishes faster than the cosmological constant.

Source: http://arxiv.org/abs/hep-th/0011152v2

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Sep 23, 2013
09/13

by
M. Porrati

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We prove in two different ways that brane dynamics gives rise to all H-monopoles predicted by S-duality of N=4, 4-dimensional superstring compactifications. One method uses heterotic-type II duality and the self-dual 3-brane dynamics, the other uses the 5-brane description of small instantons in SO(32) superstrings.

Source: http://arxiv.org/abs/hep-th/9607082v3

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Sep 22, 2013
09/13

by
M. Porrati

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Effective Field Theory (EFT) is an efficient method for parametrizing unknown high energy physics effects on low energy data. When applied to time-dependent backgrounds, EFT must be supplemented with initial conditions. In these proceedings, I briefly describe such approach, especially in the case of inflationary, almost-de Sitter backgrounds. I present certain self-consistency constraints that bound the size of possible deviations of the initial state from the standard thermal vacuum. I also...

Source: http://arxiv.org/abs/hep-th/0409210v2

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Sep 22, 2013
09/13

by
M. Porrati

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We give an argument showing that in N=4 supersymmetric gauge theories there exists at least one bound state saturating the Bogomol'nyi bound with electric charge $p$ and magnetic charge $q$, for each $p$ and $q$ relatively prime, and we comment on the uniqueness of such state. This result is a necessary condition for the existence of an exact S-duality in N=4 supersymmetric theories.

Source: http://arxiv.org/abs/hep-th/9505187v3

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Sep 18, 2013
09/13

by
S. Ferrara; M. Porrati

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We consider the inclusion of brane charges in AdS_5 superalgebras that contain the maximal central extension of the super-Poincar\'e algebra on the boundary of AdS_5. For theories with N supersymmetries on the boundary, the maximal extension is OSp(1/8N,R), which contains the group $Sp(8N,R)\supset U(2N,2N) \supset SU(2,2)\times U(N)$ as extension of the conformal group. An ``intermediate'' extension to U(2N,2N/1) is also discussed, as well as the inclusion of brane charges in AdS_7 and AdS_4...

Source: http://arxiv.org/abs/hep-th/9903241v2

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Sep 20, 2013
09/13

by
M. Porrati; A. Zaffaroni

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We present M-theory compactifications on $K_3 \times K_3$ with membranes near the $A_n$ or $D_n$ singularities of the $K_3$ spaces. By realizing each of these compactifications in two different ways as type I' models with 2- and 6-branes, we explain the three-dimensional duality between gauge theories recently found by Intriligator and Seiberg. We also find new pairs of dual gauge theories, which we briefly describe.

Source: http://arxiv.org/abs/hep-th/9611201v1

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Sep 22, 2013
09/13

by
C. Bachas; M. Porrati

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We calculate exactly the rate of pair production of open bosonic and supersymmetric strings in a constant electric field. The rate agrees with Schwinger's classic result in the weak-field limit, but diverges when the electric field approaches some critical value of the order of the string tension. (Phyzzx file)

Source: http://arxiv.org/abs/hep-th/9209032v1

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Sep 23, 2013
09/13

by
M. Porrati; R. Rahman

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We couple a massive spin 2 particle to electromagnetism. By introducing new, redundant degrees of freedom using the Stueckelberg formalism, we extract an intrinsic, model independent UV cutoff of the effective field theory describing this system. The cutoff signals both the onset of a strongly interacting dynamical regime and a finite size for the spin 2 particle. We show that the existence of a cutoff is strictly connected to other pathologies of interacting high-spin fields, such as the...

Source: http://arxiv.org/abs/0801.2581v3

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Sep 18, 2013
09/13

by
M. Porrati; A. Starinets

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Recently, it has been conjectured that supergravity solutions with two asymptotically AdS regions describe the RG flow of a 4-d field theory from a UV fixed point to an interacting IR fixed point. In this paper we lend support to this conjecture by showing that, in the UV (IR) limit, the two-point function of a minimally-coupled scalar field depends only on the UV (IR) region of the metric, asymptotic to AdS_5. This result is consistent with the interpretation of the radial coordinate of Anti...

Source: http://arxiv.org/abs/hep-th/9903085v1

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Sep 23, 2013
09/13

by
M. Porrati; R. Rabadan

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We review boundary rigidity theorems assessing that, under appropriate conditions, Riemannian manifolds with the same spectrum of boundary geodesics are isometric. We show how to apply these theorems to the problem of reconstructing a $d+1$ dimensional, negative curvature space-time from boundary data associated to two-point functions of high-dimension local operators in a conformal field theory. We also show simple, physically relevant examples of negative-curvature spaces that fail to satisfy...

Source: http://arxiv.org/abs/hep-th/0312039v2

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Sep 21, 2013
09/13

by
F. Nitti; M. Porrati

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We show that all two-dimensional conformal field theories possess a hidden sl(2,R) affine symmetry. More precisely, we add appropriate ghost fields to an arbitrary CFT, and we use them to construct the currents of sl(2,R). We then define a BRST operator whose cohomology defines a physical subspace where the extended theory coincides with the original CFT. We use the sl(2,R) algebra to construct candidate wave functions for 3-d quantum gravity coupled to matter, and we discuss their viability.

Source: http://arxiv.org/abs/hep-th/0311069v2

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Jul 20, 2013
07/13

by
M. Porrati; A. Starinets

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We discuss various aspect of the holographic correspondence between 5-d gravity and 4-d field theory. First of all, we describe deformations of N=4 Super Yang-Mills (SYM) theories in terms of 5-d gauged supergravity. In particular, we describe N=0 and N=1 deformations of N=4 SYM to confining theories. Secondly, we describe recent proposals for the holographic dual of the renormalization group and for 4-d central charges associated to it. We conclude with a ``holographic'' proof of the Goldstone...

Source: http://arxiv.org/abs/hep-th/0009198v1

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Sep 22, 2013
09/13

by
M. Porrati; L. Girardello

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Chiral gauge theories can be defined in four-dimensional Anti de Sitter space, but AdS boundary conditions explicitly break the chiral symmetry in a specific, well defined manner, which in turns results in an anomalous Ward identity. When the 4D theory admits a dual description in terms of a 3D CFT, the 3D dual of the broken chiral symmetry is a certain double-trace deformation of the CFT, which produces the same anomalous chiral Ward identities that obtains in the 4D bulk theory.

Source: http://arxiv.org/abs/0908.3487v2

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Sep 21, 2013
09/13

by
S. Ferrara; M. Porrati

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We consider the maximal central extension of the supertranslation algebra in d=4 and 3, which includes tensor central charges associated to topological defects such as domain walls (membranes) and strings. We show that for all N-extended superalgebras these charges are related to nontrivial configurations on the scalar moduli space. For N=2 theories obtained from compactification on Calabi-Yau threefolds, we give an explicit realization of the moduli-dependent charges in terms of wrapped branes.

Source: http://arxiv.org/abs/hep-th/9711116v2

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100

Jul 20, 2013
07/13

by
M. Porrati; A. Starinets

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We study monotonicity and other properties of the canonical c-function (defined through the correlator of the energy-momentum tensor) in some holographic duals of 4-d quantum field theories. The canonical c-function and its derivatives are related to the 5-d Green's function of the dual supergravity theory. While positivity of the canonical c-function is obvious, we have not found a general proof of its monotonicity, even though c is monotonic in the few explicit examples we examine in this...

Source: http://arxiv.org/abs/hep-th/0009227v1

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Sep 17, 2013
09/13

by
S. Ferrara; M. Porrati

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We argue that extremal black holes of N=4 Poincare supergravity coupled to conformal matter have a quantum-exact dual 5-d description in the maximally supersymmetric extension of the Randall-Sundrum theory. This dual is a the classical, static supergravity solution describing a string with both Neveu-Schwarz and Ramond charge with respect to different antisymmetric tensor doublets. We also discuss the issue of the singularity present in a class of such supergravity solutions found by Cvetic, Lu...

Source: http://arxiv.org/abs/hep-th/0207255v2

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2.0

Jun 30, 2018
06/18

by
S. Ferrara; M. Porrati

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The supersymmetric extension of "Starobinsky" $R+\alpha R^2$ models of inflation is particularly simple in the "new minimal" formalism of supergravity, where the inflaton has no scalar superpartners. This paper is devoted to matter couplings in such supergravity models. We show how in the new minimal formalism matter coupling presents certain features absent in other formalisms. In particular, for the large class of matter couplings considered in this paper, matter must...

Topic: High Energy Physics - Theory

Source: http://arxiv.org/abs/1407.6164

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Sep 18, 2013
09/13

by
A. Giveon; M. Porrati

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Duality groups of Abelian gauge theories on four manifolds and their reduction to two dimensions are considered. The duality groups include elements that relate different space-times in addition to relating different gauge-coupling matrices. We interpret (some of) such dualities as the geometrical symmetries of compactified theories in higher dimensions. In particular, we consider compactifications of a (self-dual) 2-form in 6-D, and compactifications of a self-dual 4-form in 10-D. Relations...

Source: http://arxiv.org/abs/hep-th/9605118v2

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28

Sep 22, 2013
09/13

by
P. Nason; M. Porrati

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We compute the effect of small-size instanton corrections to current-current correlators, for all combinations of axial, vector, and possibly flavour non-diagonal currents. We apply our result to the hadronic decays of the $\tau$ lepton, in order to assess the reliability of the determination of $\as$ from the $\tau$ hadronic width.

Source: http://arxiv.org/abs/hep-ph/9302211v1

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Sep 22, 2013
09/13

by
M. Porrati; A. Rozenberg

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We propose a general method that allows to detect the existence of normalizable ground states in supersymmetric quantum mechanical systems with non-Fredholm spectrum. We apply our method to show the existence of bound states at threshold in two important cases: 1) the quantum mechanical system describing H-monopoles; 2) the quantum mechanics of D0 branes.

Source: http://arxiv.org/abs/hep-th/9708119v4

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Sep 17, 2013
09/13

by
S. Ferrara; M. Porrati

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We describe the low-energy effective theory of N=1 spontaneously broken supegravity obtained by flux-induced breaking in the presence of n D3 branes. This theory can be obtained by integrating out three massive gravitino multiplets in the hierarchical breaking N=4 to N=3 to N=2 to N=1. This integration also eliminates the IIB complex dilaton. The resulting theory is a no-scale supergravity model, whose moduli are the three chiral multiplets that correspond to the three radii of the three 2-tori...

Source: http://arxiv.org/abs/hep-th/0207135v2

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Sep 20, 2013
09/13

by
A. Giveon; M. Porrati

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In this talk, some aspects of duality symmetries are presented.

Source: http://arxiv.org/abs/hep-th/9610159v1

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Sep 18, 2013
09/13

by
M. Porrati; J. -W. Rombouts

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We re-examine the problem of strong coupling in a regularized version of DGP (or ``brane-induced'') gravity. We find that the regularization of ref. hep-th/0304148 differs from DGP in that it does not exhibit strong coupling or ghosts up to cubic order in the interactions. We suggest that the nonlocal nature of the theory, when written in terms of the 4-D metric, is a plausible reason for this phenomenon. Finally, we briefly discuss the possible behavior of the model at higher-order in...

Source: http://arxiv.org/abs/hep-th/0401211v2

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Sep 18, 2013
09/13

by
S. Ferrara; L. Girardello; M. Porrati

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It is shown that the minimal Higgs sector of a generic N=2 supergravity theory with unbroken N=1 supersymmetry must contain a Higgs hypermultiplet and a vector multiplet. When the multiplets parametrize the quaternionic manifold SO(4,1)/SO(4), and the special Kahler manifold SU(1,1)/U(1), respectively, a vanishing vacuum energy with a sliding massive spin 3/2 multiplet is obtained. Potential applications to N=2 low energy effective actions of superstrings are briefly discussed.

Source: http://arxiv.org/abs/hep-th/9510074v1

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Sep 22, 2013
09/13

by
M. Kleban; M. Porrati; R. Rabadan

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We discuss two types of instabilities which may arise in string theory compactified to asymptotically AdS spaces: perturbative, due to discrete modes in the spectrum of the Laplacian, and non-perturbative, due to brane nucleation. In the case of three dimensional Einstein manifolds, we completely characterize the presence of these instabilities, and in higher dimensions we provide a partial classification. The analysis may be viewed as an extension of the Breitenlohner-Freedman bound. One...

Source: http://arxiv.org/abs/hep-th/0409242v1

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Sep 21, 2013
09/13

by
M. Kleban; M. Porrati; R. Rabadan

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Finite entropy thermal systems undergo Poincare recurrences. In the context of field theory, this implies that at finite temperature, timelike two-point functions will be quasi-periodic. In this note we attempt to reproduce this behavior using the AdS/CFT correspondence by studying the correlator of a massive scalar field in the bulk. We evaluate the correlator by summing over all the SL(2,Z) images of the BTZ spacetime. We show that all the terms in this sum receive large corrections after at...

Source: http://arxiv.org/abs/hep-th/0407192v2

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Sep 21, 2013
09/13

by
L. Girardello; M. Porrati; A. Zaffaroni

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Since T-duality has been proved only perturbatively and most of the heterotic states map into solitonic, non-perturbative, type II states, the 6-dimensional string-string duality between the heterotic string and the type II string is not sufficient to prove the S-duality of the former, in terms of the known T-duality of the latter. We nevertheless show in detail that perturbative T-duality, together with the heterotic-type II duality, does imply the existence of heterotic H-monopoles, with the...

Source: http://arxiv.org/abs/hep-th/9508056v1

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Sep 22, 2013
09/13

by
L. Girardello; M. Porrati; A. Zaffaroni

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We present a spontaneously broken N=2 supergravity model that reduces in the flat limit to a globally supersymmetric N=2 system with explicit soft supersymmetry breaking terms. These soft terms generate a mass O(100 GeV) for mirror quarks and leptons, while leaving the physical fermions light, thereby overcoming one of the major obstacles towards the construction of a realistic N=2 model of elementary interactions.

Source: http://arxiv.org/abs/hep-th/9704163v1

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Sep 18, 2013
09/13

by
G. Dvali; G. Gabadadze; M. Porrati

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We address the issue of whether extra dimensions could have an infinite volume and yet reproduce the effects of observable four-dimensional gravity on a brane. There is no normalizable zero-mode graviton in this case, nevertheless correct Newton's law can be obtained by exchanging bulk gravitons. This can be interpreted as an exchange of a single {\it metastable} 4D graviton. Such theories have remarkable phenomenological signatures since the evolution of the Universe becomes high-dimensional...

Source: http://arxiv.org/abs/hep-th/0002190v2

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Sep 22, 2013
09/13

by
G. Dvali; G. Gabadadze; M. Porrati

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Theories with infinite volume extra dimensions open exciting opportunities for particle physics. We argued recently that along with attractive features there are phenomenological difficulties in this class of models. In fact, there is no graviton zero-mode in this case and 4D gravity is obtained by means of continuum bulk modes. These modes have additional degrees of freedom which do not decouple at low energies and lead to inconsistent predictions for light bending and the precession of...

Source: http://arxiv.org/abs/hep-th/0003054v3

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Sep 24, 2013
09/13

by
A. Cucchieri; S. Deser; M. Porrati

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We analyse the high-energy behavior of tree-level graviton Compton amplitudes for particles of mass m and arbitrary spin, concentrating on a combination of forward amplitudes that will be unaffected by eventual cross- couplings to other, higher spins. We first show that for any spin larger than 2, tree-level unitarity is already violated at energies well below the Planck scale M, if m < < M. We then restore unitarity to this amplitude up to M by adding non-minimal couplings that depend on...

Source: http://arxiv.org/abs/hep-th/9408073v2

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31

Sep 22, 2013
09/13

by
L. Girardello; C. Piccioni; M. Porrati

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We study D-branes in the background of a gravitational shock wave. We consider the case of parallel D-branes located on opposite sides with respect to the shock wave. Their interaction is studied by evaluating the cylinder diagram using the boundary states technique. Boundary states are defined at each D-brane and their scalar product is evaluated after propagation through the shock wave. Taking the limit where the gravitational shock wave vanishes we show that the amplitude evaluated is...

Source: http://arxiv.org/abs/hep-th/0403197v2

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2.0

Jun 28, 2018
06/18

by
S. Ferrara; M. Porrati; A. Sagnotti

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A scale invariant Goldstino theory coupled to Supergravity is obtained as a standard supergravity dual of a rigidly scale invariant higher--curvature Supergravity with a nilpotent chiral scalar curvature. The bosonic part of this theory describes a massless scalaron and a massive axion in a de Sitter Universe.

Topics: High Energy Physics - Phenomenology, High Energy Physics - Theory

Source: http://arxiv.org/abs/1508.02939

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Sep 18, 2013
09/13

by
L. Girardello; M. Porrati; A. Zaffaroni

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We study a duality, recently conjectured by Klebanov and Polyakov, between higher-spin theories on AdS_4 and O(N) vector models in 3-d. These theories are free in the UV and interacting in the IR. At the UV fixed point, the O(N) model has an infinite number of higher-spin conserved currents. In the IR, these currents are no longer conserved for spin s>2. In this paper, we show that the dual interpretation of this fact is that all fields of spin s>2 in AdS_4 become massive by a Higgs...

Source: http://arxiv.org/abs/hep-th/0212181v2

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2.0

Jun 30, 2018
06/18

by
S. Ferrara; M. Porrati; A. Sagnotti

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We derive new types of $U(1)^n$ Born-Infeld actions based on N=2 special geometry in four dimensions. As in the single vector multiplet (n=1) case, the non--linear actions originate, in a particular limit, from quadratic expressions in the Maxwell fields. The dynamics is encoded in a set of coefficients $d_{ABC}$ related to the third derivative of the holomorphic prepotential and in an SU(2) triplet of N=2 Fayet-Iliopoulos charges, which must be suitably chosen to preserve a residual N=1...

Topics: High Energy Physics - Theory, Mathematics, Mathematical Physics, General Relativity and Quantum...

Source: http://arxiv.org/abs/1411.4954

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Sep 23, 2013
09/13

by
S. Ferrara; L. Girardello; M. Porrati

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We analyze the relation between rigid and local supersymmetric N=2 field theories, when half of the supersymmetries are spontaneously broken. In particular, we show that the recently found partial supersymmety breaking induced by electric and magnetic Fayet-Iliopoulos terms in rigid theories can be obtained by a suitable flat limit of previously constructed N=2 supergravity models with partial super-Higgs in the observable sector.

Source: http://arxiv.org/abs/hep-th/9512180v1

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Sep 20, 2013
09/13

by
S. Ferrara; M. Porrati; A. Zaffaroni

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It is argued that N=6 supergravity on $AdS_5$, with gauge group $SU(3)\times U(1)$ corresponds, at the classical level, to a subsector of the ``chiral'' primary operators of N=4 Yang-Mills theories. This projection involves a ``duality transformation'' of N=4 Yang-Mills theory and therefore can be valid if the coupling is at a self-dual point, or for those amplitudes that do not depend on the coupling constant.

Source: http://arxiv.org/abs/hep-th/9810063v1

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337

Jul 19, 2013
07/13

by
A. Giveon; M. Porrati; E. Rabinovici

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A review article submitted to Physics Report: Target space duality and discrete symmetries in string theory are reviewed in different settings.

Source: http://arxiv.org/abs/hep-th/9401139v1

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Jul 20, 2013
07/13

by
P. A. Grassi; G. Policastro; M. Porrati

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The quantization of the Brink-Schwarz-Casalbuoni superparticle is performed in an explicitly covariant way using the antibracket formalism. Since an infinite number of ghost fields are required, within a suitable off-shell twistor-like formalism, we are able to fix the gauge of each ghost sector without modifying the physical content of the theory. The computation reveals that the antibracket cohomology contains only the physical degrees of freedom.

Source: http://arxiv.org/abs/hep-th/0009239v1

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Sep 19, 2013
09/13

by
P. A. Grassi; G. Policastro; M. Porrati

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The quantization of the complex linear superfield requires an infinite tower of ghosts. Using the Batalin-Vilkovisky technique, Grisaru, Van Proeyen, and Zanon have been able to define a correct procedure to construct a gauge-fixed action. We generalize their technique by introducing the Lagrange multipliers into the non-minimal sector and we study the characteristic BRST cohomology. We show how the physical subspace is singled out. Finally, we quantize the model in the presence of a background...

Source: http://arxiv.org/abs/hep-th/0010052v2

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Sep 21, 2013
09/13

by
S. Ferrara; A. Masiero; M. Porrati; R. Stora

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We construct the Bardeen anomaly and its related Wess-Zumino term in the supersymmetric standard model. In particular we show that it can be written in terms of a composite linear superfield related to supersymmetrized Chern-Simons forms, in very much the same way as the Green-Schwarz term in four-dimensional string theory. Some physical applications, such as the contribution to the g-2 of gauginos when a heavy top is integrated out, are briefly discussed.

Source: http://arxiv.org/abs/hep-th/9311038v1

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Sep 20, 2013
09/13

by
L. Girardello; A. Giveon; M. Porrati; A. Zaffaroni

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Evidence in favor of $SL(2,Z)$ S-duality in $N=4$ supersymmetric Yang-Mills theories in four dimensions and with general compact, simple gauge groups is presented. (Contribution to the Proceedings of the Strings '95 conference, March 13-18, 1995, USC, and the Proceedings of the Trieste Conference on S-Duality and Mirror Symmetry, June 5-9, 1995.)

Source: http://arxiv.org/abs/hep-th/9507064v1

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Sep 20, 2013
09/13

by
L. Girardello; M. Petrini; M. Porrati; A. Zaffaroni

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We find new, local, non-supersymmetric conformal field theories obtained by relevant deformations of the N=4 super Yang Mills theory in the large $N$ limit. We contruct interpolating supergravity solutions that naturally represent the flow from the N=4 super Yang Mills UV theory to these non-supersymmetric IR fixed points. We also study the linearization around the N=4 superconformal point of N=1 supersymmetric, marginal deformations. We show that they give rise to N=1 superconformal fixed...

Source: http://arxiv.org/abs/hep-th/9810126v5