| 1. |
- Bundzik, Daniel
(author)
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Star product and the general Leigh-Strassler deformation
- 2007
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In: Journal of High Energy Physics (JHEP). - : SISSA. - 1126-6708 .- 1029-8479. ; :04
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Journal article (peer-reviewed)abstract
- We extend the definition of the star product introduced by Lunin and Maldacena to study marginal deformations of = 4 SYM. The essential difference from the latter is that instead of considering U(1) × U(1) non-R-symmetry, with charges in a corresponding diagonal matrix, we consider two 3-symmetries followed by an SU(3) transformation, with resulting off-diagonal elements. From this procedure we obtain a more general Leigh–Strassler deformation, including cubic terms with the same index, for specific values of the coupling constants. We argue that the conformal property of = 4 SYM is preserved, in both β- (one-parameter) and γi-deformed (three-parameters) theories, since the deformation for each amplitude can be extracted in a prefactor. We also conclude that the obtained amplitudes should follow the iterative structure of MHV amplitudes found by Bern, Dixon and Smirnov.
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| 2. |
- Månsson, Teresia, 1974-
(author)
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The Liegh-Strassler deformation and the quest for integrability
- 2007
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In: Journal of High Energy Physics (JHEP). - : Institute of Physics Publishing (IOPP). - 1126-6708 .- 1029-8479.
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Journal article (peer-reviewed)abstract
- In this paper we study the one-loop dilatation operator of the full scalar field sector of Leigh-Strassler deformed =4 SYM theory. In particular we map it onto a spin chain and find the parameter values for which the Reshetikhin integrability criteria are fulfilled. Some years ago Roiban found an integrable subsector, consisting of two holomorphic scalar fields, corresponding to the XXZ model. He was pondering about the existence of a subsector which would form generalisation of that model to an integrable q(3) model. Later Berenstein and Cherkis added one more holomorphic field and showed that the subsector obtained this way cannot be integrable except for the case when q = eiβ, β. In this work we show if we add an anti-holomorphic field to the two holomorphic ones, we get indeed an integrable q(3) subsector. We find it plausible that a direct generalisation to a q(2|3) one-loop sector will exist, and possibly beyond one-loop.
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| 3. |
- Bundzik, Daniel, et al.
(author)
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The general Leigh-Strassler deformation and integrability
- 2006
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; :1
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Journal article (peer-reviewed)abstract
- The success of the identification of the planar dilatation operator of N = 4 SYM with an integrable spin chain Hamiltonian has raised the question if this also is valid for a deformed theory. Several deformations of SYM have recently been under investigation in this context. In this work we consider the general Leigh-Strassler deformation. For the generic case the S-matrix techniques cannot be used to prove integrability. Instead we use R-matrix techniques to study integrability. Some new integrable points in the parameter space are found.
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| 4. |
- Argurio, Riccardo, 1972, et al.
(author)
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Massless fermionic bound states and the gauge/gravity correspondence
- 2006
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 03:2006, s. 043-
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Journal article (peer-reviewed)abstract
- We study the equations of motion of fermions in type IIB supergravity in the context of the gauge/gravity correspondence. The main motivation is the search for normalizable fermionic zero modes in such backgrounds, to be interpreted as composite massless fermions in the dual theory. We specialize to backgrounds characterized by a constant dilaton and a self-dual three-form. In the specific case of the Klebanov-Strassler solution we construct explicitly the fermionic superpartner of the Goldstone mode associated with the broken baryonic symmetry. The fermionic equations could also be used to search for goldstinos in theories that break supersymmetry dynamically.
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| 5. |
- Henningson, Måns, 1964, et al.
(author)
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Zero-energy bound states of N=4 SYM on T^3: S-duality and the mapping class group
- 2008
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 0804:4, s. 066-
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Journal article (peer-reviewed)abstract
- We continue our studies of the low-energy spectrum of N = 4 super-Yang-Mills theory on a spatial three-torus. In two previous papers, we computed the spectrum of normalizable zero-energy states for all choices of gauge group and all values of the electric and magnetic 't Hooft fluxes, and checked its invariance under the SL2(Z) S-duality group. In this paper, we refine the analysis by also decomposing the space of bound states into irreducible unitary representations of the SL3(Z) mapping class group of the three-torus. We perform a detailed study of the S-dual pairs of theories with gauge groups Spin(2n+1) and Sp(2n). The predictions of S-duality (which commutes with the mapping class group) are fulfilled as expected, but the proof requires some surprisingly intricate combinatorial infinite product identities.
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| 6. |
- Akhmedov, Evgeny K., et al.
(author)
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Series expansions for three-flavor neutrino oscillation probabilities in matter
- 2004
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In: Journal of High Energy Physics (JHEP). - : IOP Publishing. - 1126-6708 .- 1029-8479. ; 2004:04, s. 078-
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Journal article (peer-reviewed)abstract
- We present a number of complete sets of series expansion formulas for neutrino oscillation probabilities in matter of constant density for three flavors. In particular, we study expansions in the mass hierarchy parameter alpha = Deltam(21)(2)/Deltam(31)(2) and mixing parameter s(13) = sin theta(13) up to second order and expansions only in alpha and only in s(13) up to first order. For each type of expansion we also present the corresponding formulas for neutrino oscillations in vacuum. We perform a detailed analysis of the accuracy of the different sets of series expansion formulas and investigate which type of expansion is most accurate in different regions of the parameter space spanned by the neutrino energy E, the baseline length L, and the expansion parameters alpha and s(13). We also present the formulas for series expansions in alpha and in s(13) up to first order for the case of arbitrary matter density profiles. Furthermore, it is shown that in general all the 18 neutrino and antineutrino oscillation probabilities can be expressed through just two independent probabilities.
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| 7. |
- Blennow, Mattias, et al.
(author)
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Damping signatures in future neutrino oscillation experiments
- 2005
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In: Journal of High Energy Physics (JHEP). - : IOP Publishing. - 1126-6708 .- 1029-8479. ; 2005:06, s. 049-
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Journal article (peer-reviewed)abstract
- We discuss the phenomenology of damping signatures in the neutrino oscillation probabilities, where either the oscillating terms or the probabilities can be damped. This approach is a possibility for tests of damping effects in future neutrino oscillation experiments, where we mainly focus on reactor and long-baseline experiments. We extensively motivate different damping signatures due to small corrections by neutrino decoherence, neutrino decay, oscillations into sterile neutrinos, or other mechanisms, and classify these signatures according to their energy ( spectral) dependencies. We demonstrate, at the example of short baseline reactor experiments, that damping can severely alter the interpretation of results, e. g., it could fake a value of sin(2)(2 theta(13)) smaller than the one provided by Nature. In addition, we demonstrate how a neutrino factory could constrain different damping models with emphasis on how these different models could be distinguished, i.e., how easily the actual type of effect could be identified. We find that the damping models cluster in different categories, which can be much better distinguished from each other than models within the same cluster.
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| 8. |
- Meloni, Davide, et al.
(author)
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Exact and approximate formulas for neutrino mixing and oscillations with non-standard interactions
- 2009
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In: Journal of High Energy Physics (JHEP). - : IOP Publishing. - 1126-6708 .- 1029-8479. ; 2009:04, s. 033-
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Journal article (peer-reviewed)abstract
- We present, both exactly and approximately, a complete set of mappings between the vacuum (or fundamental) leptonic mixing parameters and the effective ones in matter with non-standard neutrino interaction (NSI) effects included. Within the three-flavor neutrino framework and a constant matter density profile, a full set of sum rules is established, which enables us to reconstruct the moduli of the effective leptonic mixing matrix elements, in terms of the vacuum mixing parameters in order to reproduce the neutrino oscillation probabilities for future long-baseline experiments. Very compact, but quite accurate, approximate mappings are obtained based on series expansions in the neutrino mass hierarchy parameter eta equivalent to Delta m(21)(2)/Delta m(31)(2), the vacuum leptonic mixing parameter s(13) equivalent to sin theta(13), and the NSI parameters epsilon(alpha beta). A detailed numerical analysis about how the NSIs affect the smallest leptonic mixing angle theta(13), the deviation of the leptonic mixing angle theta(23) from its maximal mixing value, and the transition probabilities useful for future experiments are performed using our analytical results.
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| 9. |
- Agarwal, Abhishek, et al.
(author)
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Higher charges in dynamical spin chains for SYM theory
- 2005
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; :10, s. 1291-1302
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Journal article (peer-reviewed)abstract
- We construct, to the first two non-trivial orders, the next conserved charge in the su(2|3) sector of N=4 Super Yang-Mills theory. This represents a test of integrability in a sector where the interactions change the number of sites of the chain. The expression for the charge is completely determined by the algebra and can be written in a diagrammatic form in terms of the interactions already present in the Hamiltonian. It appears likely that this diagrammatic expression remains valid in the full theory and can be generalized to higher loops and higher charges thus helping in establishing complete integrability for these dynamical chains.
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| 10. |
- Ananth, S., et al.
(author)
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Eleven-dimensional supergravity in light-cone superspace
- 2005
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 5:5, s. 56-71
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Journal article (peer-reviewed)abstract
- We show that Supergravity in eleven dimensions can be described in terms of a constrained superfield on the light-cone, without the use of auxiliary fields. We build its action to first order in the gravitational coupling constant \kappa, by "oxidizing" (N=8,d=4) Supergravity. This is simply achieved, as for N=4 Yang-Mills, by extending the transverse derivatives into superspace. The eleven-dimensional SuperPoincare algebra is constructed and a fourth order interaction is conjectured.
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| 11. |
- Bachas, Constantin, et al.
(author)
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Nahm's equations, {$\scr N=1^*$} domain walls, and {D}-strings in {${\rm AdS}_5\times S_5$}
- 2001
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In: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; :7, s. Paper 41,28-
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Journal article (peer-reviewed)abstract
- We consider the following two problems: classical domain walls in the = 1* mass deformation of the maximally supersymmetric Yang Mills theory, and D-strings as external magnetic sources in the context of the AdS/CFT correspondence. We show that they are both described by Nahm's equations with unconventional boundary conditions, and analyze the relevant moduli space of solutions. We argue that general `fuzzy sphere' configurations of D-strings in AdS5 correspond to Wilson-'t Hooft lines in higher representations of the dual SU(n) gauge theory.
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| 12. |
- Bao, Ling, 1980, et al.
(author)
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A note on topological M5-branes and string-fivebrane duality
- 2008
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2008:6, s. 11-
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Journal article (peer-reviewed)abstract
- We derive the stability conditions for the M5-brane in topological M-theory using k-symmetry. The non-linearly self-dual 3-form on the world-volume is necessarily non-vanishing, as is the case also for the 2-form field strengths on coisotropic branes in topological string theory. It is demonstrated that the self-duality is consistent with the stability conditions, which are solved locally in terms of a tensor in the representation 6 of SU(3) subset of G(2). The double dimensional reduction of the M5-brane is the D4-brane, and its direct reduction is an NS5-brane. We show that the equation of motion for the 3-form on the NS5-brane wrapping a Calabi-Yau space is exactly the Kodaira-Spencer equation, providing support for a string-fivebrane duality in topological string theory.
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| 13. |
- Brink, Lars, 1943, et al.
(author)
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E7(7) on the Light Cone
- 2008
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2008:6
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Journal article (peer-reviewed)abstract
- We use the Cremmer-Julia E-7(7) non-linear symmetry of N = 8 Supergravity to derive its order k(2) on-shell Hamiltonian in terms of one chiral light-cone superfield. By requiring that E-7(7) commute with the super-Poincare group, we deduce to lowest non-trivial order in k, the light cone E-7(7) transformations of all fields of the theory, including the gravition. We then derive the dynamical supersymmetry transformation to order k(2), and express the Hamiltonian as a quadratic form in the chiral superfield.
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| 14. |
- Brink, Lars, 1943, et al.
(author)
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E8(8) in Light Cone Superspace
- 2008
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2008:7
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Journal article (peer-reviewed)abstract
- We derive the non-linear action of E-8(8) on the constrained chiral superfield in the light-cone superspace with eight complex Grassmann variables. We construct (to lowest order in the coupling) the sixteen dynamical supersymmetries which generate a Hamiltonian with E-8(8) invariance in three space-time dimensions, and show that it has only interactions with even powers of the coupling constant.
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| 15. |
- Chialva, Diego, et al.
(author)
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Deforming, revolving and resolving : New paths in the string theory landscape
- 2008
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In: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; 02
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Journal article (peer-reviewed)abstract
- In this paper we investigate the properties of series of vacua in the string theory landscape. In particular, we study minima to the flux potential in type IIB compactifications on the mirror quintic. Using geometric transitions, we embed its one-dimensional complex structure moduli space in that of another Calabi-Yau with h1,1 = 86 and h2,1 = 2. We then show how to construct infinite series of continuously connected minima to the mirror quintic potential by moving into this larger moduli space, applying its monodromies, and moving back. We provide an example of such series, and discuss their implications for the string theory landscape
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| 16. |
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| 17. |
- Eriksson, David, et al.
(author)
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New angles on top quark decay to a charged Higgs
- 2009
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In: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; 01:1, s. 024-
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Journal article (peer-reviewed)abstract
- To properly discover a charged Higgs Boson (H±) requires its spin and couplings to be determined. We investigate how to utilize t spin correlations to analyze the H± couplings in the decay t → bH+ → bτ+ντ. Within the framework of a general Two-Higgs-Doublet Model, we obtain results on the spin analyzing coefficients for this decay and study in detail its spin phenomenology, focusing on the limits of large and small values for tan β. Using a Monte Carlo approach to simulate full hadron-level events, we evaluate systematically how the H± → τ±ντ decay mode can be used for spin analysis. The most promising observables are obtained from azimuthal angle correlations in the transverse rest frames of t(). This method is particularly useful for determining the coupling structure of H± in the large tan β limit, where differences from the SM are most significant.
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| 18. |
- Ferretti, Gabriele, 1963, et al.
(author)
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Instantons and Toric Quiver Gauge Theories
- 2008
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2008:7
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Journal article (peer-reviewed)abstract
- We show how to construct the general action coupling (multi)instantons to gauge theories arising from branes probing arbitrary toric singularities. We give a general set of rules for how to construct such an action given the knowledge of the superpotential for the gauge theory. The main idea is to obtain the action by higgsing a theory whose instanton dynamics is known, namely an orbifold of N=4 super Yang-Mills. We find that the couplings of the fermionic zero-modes with the holomorphic fields are dictated by the structure of the superpotential describing the toric singularity. We present explicit examples such as the Suspended Pinch Point, the Conifold and the first three del Pezzo's. We perform various checks on these results by further higgsing to smaller orbifolds and present some applications, including both gauge theory and stringy instantons.
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| 19. |
- Ferretti, Gabriele, 1963, et al.
(author)
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Non-Perturbative Effects on a Fractional D3-Brane
- 2009
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 03:3, s. 040-
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Journal article (peer-reviewed)abstract
- In this note we study the N = 1 abelian gauge theory on the world volume of a single fractional D3-brane. In the limit where gravitational interactions are not completely decoupled we find that a superpotential and a fermionic bilinear condensate are generated by a D-brane instanton effect. A related situation arises for an isolated cycle invariant under an orientifold projection, even in the absence of any gauge theory brane. Moreover, in presence of supersymmetry breaking background fluxes, such instanton configurations induce new couplings in the 4-dimensional effective action, including non-perturbative contributions to the cosmological constant and non-supersymmetric mass terms.
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| 20. |
- Giangreco Marotta Puletti, Valentina
(author)
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Aspects of quantum integrability for pure spinor superstring in AdS5 × S5
- 2008
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In: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; :09, s. 070-
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Journal article (peer-reviewed)abstract
- We consider the monodromy matrix for the pure spinor IIB superstring on AdS5 × S5 at leading order at strong coupling, in particular its variation under an infinitesimal and continuous deformation of the contour. Such variation is equivalent to the insertion of a local operator. Demanding the BRST-closure for such an operator rules out its existence, implying that the monodromy matrix remains contour-independent at the first order in perturbation theory. Furthermore we explicitly compute the field strength corresponding to the flat connections up to leading order and directly check that it is free from logarithmic divergences. The absence of anomaly in the coordinate transformation of the monodromy matrix and the UV-finiteness of the curvature tensor finally imply the integrability of the pure spinor superstring at the first order.
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| 21. |
- Gran, Ulf, 1973, et al.
(author)
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Geometry of all supersymmetric four-dimensional N=1 supergravity backgrounds
- 2008
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 06:6, s. 102-
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Journal article (peer-reviewed)abstract
- We solve the Killing spinor equations of ${\cal N}=1$ supergravity, with four supercharges, coupled to any number of vector and scalar multiplets in all cases. We find that backgrounds with N=1 supersymmetry admit a null, integrable, Killing vector field. There are two classes of N=2 backgrounds. The spacetime in the first class admits a parallel null vector field and so it is a pp-wave. The spacetime of the other class admits three Killing vector fields, and a vector field that commutes with the three Killing directions. These backgrounds are of cohomogeneity one with homogenous sections either $\bR^{2,1}$ or $AdS_3$ and have an interpretation as domain walls. The N=3 backgrounds are locally maximally supersymmetric. There are N=3 backgrounds which arise as discrete identifications of maximally supersymmetric ones. The maximally supersymmetric backgrounds are locally isometric to either $\bR^{3,1}$ or $AdS_4$.
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| 22. |
- Gran, Ulf, 1973, et al.
(author)
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Geometry of all supersymmetric type I backgrounds
- 2007
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; :8, s. 074-
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Journal article (peer-reviewed)abstract
- We find the geometry of all supersymmetric type I backgrounds by solving the gravitino and dilatino Killing spinor equations, using the spinorial geometry technique, in all cases. The solutions of the gravitino Killing spinor equation are characterized by their isotropy group in Spin(9,1), while the solutions of the dilatino Killing spinor equation are characterized by their isotropy group in the subgroup Sigma(P) of Spin(9,1) which preserves the space of parallel spinors P. Given a solution of the gravitino Killing spinor equation with L parallel spinors, L = 1,2,3,4,5,6,8, the dilatino Killing spinor equation allows for solutions with N supersymmetries for any 0
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| 23. |
- Gran, Ulf, 1973, et al.
(author)
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IIB solutions with N>28 Killing spinors are maximally supersymmetric
- 2007
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2007:12, s. 070-
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Journal article (peer-reviewed)abstract
- We show that all IIB supergravity backgrounds which admit more than 28 Killing spinors are maximally supersymmetric. In particular, we find that for all N>28 backgrounds the supercovariant curvature vanishes, and that the quotients of maximally supersymmetric backgrounds either preserve all 32 or N
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| 24. |
- Gran, Ulf, 1973, et al.
(author)
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On relating multiple M2 and D2-branes
- 2008
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2008:10
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Journal article (peer-reviewed)abstract
- Due to the difficulties of finding superconformal Lagrangian theories for multiple M2-branes, we will in this paper instead focus on the field equations. By relaxing the requirement of a Lagrangian formulation we can explore the possibility of having structure constants fABCD satisfying the fundamental identity but which are not totally antisymmetric. We exemplify this discussion by making use of an explicit choice of a non-antisymmetric fABCD constructed from the Lie algebra structure constants fabc of an arbitrary gauge group. Although this choice of fABCD does not admit an obvious Lagrangian description, it does reproduce the correct SYM theory for a stack of N D2-branes to leading order in gYM−1 upon reduction and, moreover, it sheds new light on the centre of mass coordinates for multiple M2-branes.
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| 25. |
- Grumiller, Daniel, 1973-, et al.
(author)
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Instability in cosmological topologically massive gravity at the chiral point
- 2008
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In: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; :7, s. 134-
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Journal article (peer-reviewed)abstract
- We consider cosmological topologically massive gravity at the chiral point with positive sign of the Einstein-Hilbert term. We demonstrate the presence of a negative energy bulk mode that grows linearly in time. Unless there are physical reasons to discard this mode, this theory is unstable. To address this issue we prove that the mode is not pure gauge and that its negative energy is time-independent and finite. The isometry generators L0 and 0 have non-unitary matrix representations like in logarithmic CFT. While the new mode obeys boundary conditions that are slightly weaker than the ones by Brown and Henneaux, its fall-off behavior is compatible with spacetime being asymptotically AdS3. We employ holographic renormalization to show that the variational principle is well-defined. The corresponding Brown-York stress tensor coincides with that of global AdS3. Finally we address possibilities to eliminate the instability and prospects for chiral gravity.
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