General Supergravity Research Articles

On the implementation of the canonical quantum simplicity constraint

In this paper, we discuss several approaches to solve the quadratic and linear simplicity constraints in the context of the canonical formulations of higher dimensional general relativity and supergravity developed in our companion papers. Since the canonical quadratic simplicity constraint operators have been shown to be anomalous in any dimension D ⩾ 3 in Class. Quantum Grav. 30 045003, non-standard methods have to be employed to avoid inconsistencies in the quantum theory. We show that one can choose a subset of quadratic simplicity constraint operators which are non-anomalous among themselves and allow for a natural unitary map of the spin networks in the kernel of these simplicity constraint operators to the SU(2)-based Ashtekar–Lewandowski Hilbert space in D = 3. The linear constraint operators on the other hand are non-anomalous by themselves; however, their solution space is shown to differ in D = 3 from the expected Ashtekar–Lewandowski Hilbert space. We comment on possible strategies to make a connection to the quadratic theory. Also, we comment on the relation of our proposals to the existing work in the spin foam literature and how these works could be used in the canonical theory. We emphasize that many ideas developed in this paper are certainly incomplete and should be considered as suggestions for possible starting points for more satisfactory treatments in the future.

Sgoldstino inflation

We discuss the possibility that inflation is driven by the sgoldstino, the superpartner of the goldstino. Unlike in generic supergravity scenarios, the sgoldstino decouples from all other fields in the theory, which allows for a simple and robust inflationary model. We argue that the two-field model given by this single complex scalar correctly captures the full multifield inflationary phenomenology. On the other hand, the assumption of stability, along the entire inflationary trajectory, of the supersymmetry-preserving sector that is integrated out leads to supplementary constraints on the parent supergravity. We investigate small field, large field and hybrid sgoldstino inflation scenarios and provide some working examples. They are subject to the usual fine-tuning issues that are common to all supergravity models of inflation. We comment on some other recently proposed sgoldstino inflation models.

Intersecting brane models and F-theory in six dimensions

We analyze six-dimensional supergravity theories coming from intersecting brane models on the toroidal orbifold T4/Z2. We use recently developed tools for mapping general 6D supergravity theories to F-theory to identify F-theory constructions dual to the intersecting brane models. The F-theory picture illuminates several aspects of these models. In particular, we have some new insight into the matter spectrum on intersecting branes, and analyze gauge group enhancement as branes approach orbifold points. These novel features of intersecting brane models are also relevant in four dimensions, and are confirmed in 6D using more standard Chan–Paton methods.

HKT geometry and fake five-dimensional supergravity

Recent results on the relation between hyper-Kähler geometry with torsion and solutions admitting Killing spinors in minimal de Sitter supergravity are extended to more general supergravity models with vector multiplets.

Gravitational duality in General Relativity and Supergravity theories

We quickly review the current status of gravitational duality in General Relativity. We summarize and comment some recent work on constructing dual (topological) charges and understanding how this duality acts in supergravity theories.

Soft supersymmetry breaking with tiny cosmological constant in flux compactified [formula omitted] supergravity

Using the flux compactification scenario in a generic supergravity model we propose a set of conditions which will generate de-Sitter or anti-de-Sitter vacua for appropriate choices of the parameters in superpotential. It is shown that a mass spectrum consistent with softly broken TeV scale supersymmetry in a minimal supersymmetric standard model at the observable sector can be obtained along with a tiny cosmological constant when the Kähler and superpotential of the hidden sector satisfy a set of general constraints. Constructing a specific model which satisfy the above constraints, it is demonstrated that all the hidden sector fields have vacuum expectation values close to Planck scale and the resulting low energy potential does not have any flat direction.

More on massive 3D supergravity

Completing earlier work on three-dimensional (3D) supergravity with curvature-squared terms, we construct the general supergravity extension of ‘cosmological’ massive gravity theories. In particular, we show that all adS vacua of ‘new massive gravity’ (NMG) correspond to supersymmetric adS vacua of a ‘super-NMG’ theory that is perturbatively unitary whenever the corresponding NMG theory is perturbatively unitary.

On maximal massive 3D supergravity

We construct, at the linearized level, the three-dimensional (3D) supersymmetric ‘general massive supergravity’ and the maximally supersymmetric ‘new massive supergravity’. We also construct the maximally supersymmetric linearized topologically massive supergravity, although we expect to be maximal at the nonlinear level.

Supersymmetric intersecting branes on the waves

We construct a general family of supersymmetric solutions in time- and space-dependent wave backgrounds in general supergravity theories describing single and intersecting p-branes embedded into time-dependent dilaton-gravity plane waves of an arbitrary (isotropic) profile, with the brane world-volume aligned parallel to the propagation direction of the wave. We discuss how many degrees of freedom we have in the solutions. We also propose that these solutions can be used to describe higher-dimensional time-dependent “black holes”, and discuss their property briefly.

Gravitino dark matter in hybrid gauge-gravity models

We study the phenomenology of generic supergravity models in which gravity mediation naturally competes with gauge mediation as the origin of supergravity-breaking. This class of hybrid models has been recently motivated in string inspired constructions and differs from usual gauge mediated supersymmetry breaking models in having messenger masses of order of the GUT scale. In these scenarios the gravitino can be the lightest supersymmetric particle in wide regions of the parameter space and therefore a potential candidate for dark matter. We investigate this possibility, imposing the WMAP bound on its relic abundance and taking into account constraints from Big Bang nucleosynthesis. We show that in these constructions viable gravitino dark matter can be obtained in specific regions of the parameter space, featuring large values of tan β and where the supersymmetry breaking mechanism is dominated by gauge mediation.

Supersymmetric intersecting branes in time-dependent backgrounds

We construct a fairy general family of supersymmetric solutions in time- and space-dependent backgrounds in general supergravity theories. One class of the solutions are intersecting brane solutions with factorized form of time- and space-dependent metrics, the second class are brane solutions in pp-wave backgrounds carrying spacetime-dependence, and the final class are the intersecting branes with more nontrivial spacetime-dependence, and their intersection rules are given. Physical properties of these solutions are discussed, and the relation to existing literature is also briefly mentioned. The number of remaining supersymmetries are identified for various configurations including single branes, D1-D5, D2-D6-branes with nontrivial dilaton, and their possible dual theories are briefly discussed.

Stau detection at neutrino telescopes in scenarios with supersymmetric dark matter

We have studied the detection of long-lived staus at the IceCube neutrino telescope, after their production inside the Earth through the inelastic scattering of high energy neutrinos. The theoretical predictions for the stau flux are calculated in two scenarios in which the presence of long-lived staus is naturally associated to viable supersymmetric dark matter. Namely, we consider the cases with superWIMP (gravitino or axino) and neutralino dark matter (along the coannihilation region). In both scenarios the maximum value of the stau flux turns out to be about 1 event/yr in regions with a light stau. This is consistent with light gravitinos, with masses constrained by an upper limit which ranges from 0.2 to 15 GeV, depending on the stau mass. Likewise, it is compatible with axinos with a mass of about 1 GeV and a very low reheating temperature of order 100 GeV. In the case of the neutralino dark matter this favours regions with a low value of tan β, for which the neutralino-stau coannihilation region occurs for smaller values of the stau mass. Finally, we study the case of a general supergravity theory and show how for specific choices of non-universal soft parameters the predicted stau flux can increase moderately.

Note on rotating charged black holes in Einstein-Maxwell-Chern-Simons theory

We show that the general solution of Chong, Cvetic, Lu and Pope for nonextremal rotating charged black holes in five-dimensional minimal gauged supergravity, or equivalently in the Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant and with the Chern-Simons coefficient {nu}=1, admits a simple description in a Kerr-Schild type framework with two scalar functions. Next, assuming this framework as an ansatz, we obtain new analytic solutions for slowly rotating charged black holes in the Einstein-Maxwell-Chern-Simons theory with {nu}{ne}1. Using a covariant superpotential derived from Noether identities within the Katz-Bicak-Lynden-Bell approach, we calculate the mass and angular momenta for the general supergravity solution as well as for the slowly rotating solution with two independent rotation parameters. For the latter case, we also calculate the gyromagnetic ratios and obtain simple analytic formulas, involving both the parameters of the black holes and the Chern-Simons coefficient.

LOCALIZATION OF FERMIONIC FIELDS ON BRANEWORLDS WITH BULK TACHYON MATTER

Recently, Pal and Skar in Ref. 33 proposed a mechanism to arise the warped braneworld models from bulk tachyon matter, which are endowed with a thin brane and a thick brane. In this framework, we investigate localization of fermionic fields on these branes. As in the 1/2-spin case, the field can be localized on both the thin and thick branes with inclusion of scalar background. In the 3/2-spin extension, the general supergravity action coupled to chiral supermultiplets is considered to produce the localization on both the branes as a result.

Constraints from F and D supersymmetry breaking in general supergravity theories

AbstractWe study the conditions under which a generic supergravity model involving chiral and vector multiplets can admit vacua with spontaneously broken supersymmetry and realistic cosmological constant. We find that the existence of such viable vacua implies some constraints involving the curvature tensor of the scalar geometry and the charge and mass matrices of the vector fields, and also that the vector of F and D auxiliary fields defining the Goldstino direction is constrained to lie within a certain domain. We illustrate the relevance of these results through some examples and also discuss the implications of our general results on the dynamics of moduli fields in string models. This contribution is based on [1–3].

Curvature in Special Base Conformal Warped Products

We introduce the concept of a base conformal warped product of two pseudo-Riemannian manifolds. We also define a subclass of this structure called as a special base conformal warped product. After, we explicitly mention many of the relevant fields where metrics of these forms and also considerations about their curvature related properties play important rolls. Among others, we cite general relativity, extra-dimension, string and super-gravity theories as physical subjects and also the study of the spectrum of Laplace-Beltrami operators on p-forms in global analysis. Then, we give expressions for the Ricci tensor and scalar curvature of a base conformal warped product in terms of Ricci tensors and scalar curvatures of its base and fiber, respectively. Furthermore, we introduce specific identities verified by particular families of, either scalar or tensorial, nonlinear differential operators on pseudo-Riemannian manifolds. The latter allow us to obtain new interesting expressions for the Ricci tensor and scalar curvature of a special base conformal warped product and it turns out that not only the expressions but also the analytical approach used are interesting from the physical, geometrical and analytical point of view. Finally, we analyze, investigate and characterize possible solutions for the conformal and warping factors of a special base conformal warped product, which guarantee that the corresponding product is Einstein. Besides all, we apply these results to a generalization of the Schwarzschild metric.

Metastable supergravity vacua withFandDsupersymmetry breaking

We study the conditions under which a generic supergravity model involving chiral and vector multiplets can admit viable metastable vacua with spontaneously broken supersymmetry and realistic cosmological constant. To do so, we impose that on the vacuum the scalar potential and all its first derivatives vanish, and derive a necessary condition for the matrix of its second derivatives to be positive definite. We study then the constraints set by the combination of the flatness condition needed for the tuning of the cosmological constant and the stability condition that is necessary to avoid unstable modes. We find that the existence of such a viable vacuum implies a condition involving the curvature tensor for the scalar geometry and the charge and mass matrices for the vector fields. Moreover, for given curvature, charges and masses satisfying this constraint, the vector of F and D auxiliary fields defining the Goldstino direction is constrained to lie within a certain domain. The effect of vector multiplets relative to chiral multiplets is maximal when the masses of the vector fields are comparable to the gravitino mass. When the masses are instead much larger or much smaller than the gravitino mass, the effect becomes small and translates into a correction to the effective curvature. We finally apply our results to some simple classes of examples, to illustrate their relevance.

One-loop conformal invariance of the type II pure spinor superstring in a curved background

We compute the one-loop beta function for the Type II superstring using the pure spinor formalism in a generic supergravity background. It is known that the classical pure spinor BRST symmetry puts the background fields on-shell. In this paper we show that the one-loop beta functions vanish as a consequence of the classical BRST symmetry of the action.

GLAST versus PAMELA: a comparison between the detection of gamma rays andpositrons from neutralino annihilation

We study the indirect detection of neutralino dark matter using positrons and gammarays from its annihilation in the galactic halo. Considering the HESS data as thespectrum constituting the gamma ray background, we compare the prospects for theexperiments GLAST and PAMELA in a general supergravity framework withnon-universal scalar and gaugino masses. We show that with a boost factor of about10, PAMELA will be competitive with GLAST for typical NFW cuspy profiles.

Aspects of D-brane dynamics in supergravity backgrounds with fluxes, kappa-symmetry and equations of motion. Part IIB

We derive and carry out a detailed analysis of the equations of motion of the type IIB D-branes in generic supergravity backgrounds with fluxes making account of the worldvolume Born–Infeld gauge field and putting a special emphasis on the structure of the Dirac equation for D p-brane fermionic modes. We present an explicit form of the worldvolume field equations for each of the D p-branes ( p = 1 , 3 , 5 , 7 , 9 ) in the cases in which the Neveu–Schwarz flux and the Ramond–Ramond p-form flux along the D p-brane worldvolume are zero and the supergravity backgrounds do not necessarily induce the worldvolume Born–Infeld flux. We then give several examples of D3-, D5- and D7-brane configurations in which the worldvolume Born–Infeld flux is intrinsically non-zero and therefore must be taken into account in studying problems where such branes are involved. The examples include D3- and D5-brane instantons carrying (self-dual) worldvolume gauge fields in warped compactification backgrounds.