Generalized Supergravity Equations Research Articles

Jacobi–Lie Models and Supergravity Equations

Abstract Poisson–Lie T-duality/plurality was recently generalized to Jacobi–Lie T-plurality formulated in terms of double field theory and based on Leibniz algebras given by the structure coefficients fabc, fcab, and Za, Za. We investigate three- and four-dimensional sigma models corresponding to six-dimensional Leibniz algebras with fbba ≠ 0, Za = 0. We show that these algebras are plural one to another and, moreover, to an algebra with fbba = 0, Za = 0. These pluralities are used for construction of Jacobi–Lie models. It was conjectured that plural models should satisfy generalized supergravity equations. We have found examples of models satisfying “true” generalized supergravity equations where no trivialization to usual supergravity equations is possible. On the other hand, we show that there are also models corresponding to algebras with fbba ≠ 0, Za = 0 where the Killing vector appearing in generalized supergravity equations either vanishes or can be removed by suitable gauge transformation. Such models then satisfy usual supergravity equations, i.e. vanishing beta-function equations.

Generalized 11D supergravity equations from tri-vector deformations

In Bakhmatov et al. (Phys. Rev. D 105(8): L081904, 2022) we presented a modification of 11-dimensional supergravity field equations which upon dimensional reduction yields generalized supergravity equations in 10-dimensions. In this paper we provide full technical details of that result which is based on SL(5) exceptional field theory. The equations are obtained by making a non-unimodular tri-vector Yang-Baxter deformation which breaks the initial local diffeomorphism symmetry in 11 dimensions down to separate coordinate transformations in external 7 and internal 4 directions. We also give some non-trivial solutions to these equations.

Compatibility of Poisson–Lie transformations and symmetries of generalized supergravity equations

We investigate two types of transformations that keep NS–NS generalized supergravity equations satisfied: chi -symmetry (20) that shifts dilaton and gauge transformations (30) that change both dilaton and vector field J. Due to these symmetries there is a large set of dilatons and vector fields J that (for a fixed metric and B-field) satisfy generalized supergravity equations but only some of them can be be used as input for Poisson–Lie transformations. Conditions that define the admissible dilatons are given and examples are presented.

Generalizing eleven-dimensional supergravity

We develop a procedure to reproduce the ten-dimensional generalized supergravity equations from T-duality covariant equations, that facilitates generalization to U-duality covariant formulations of eleven-dimensional supergravity. The latter leads to a modification of the eleven-dimensional supergravity equations with terms that contain a rank-2 tensor field $J^{mn}$ which is the eleven-dimensional analog of the non-unimodularity Killing vector $I^m$ in ten dimensions.

Poisson\u2013Lie transformations and generalized supergravity equations

In this paper we investigate Poisson–Lie transformation of dilaton and vector field {mathcal {J}} appearing in generalized supergravity equations. While the formulas appearing in literature work well for isometric sigma models, we present examples for which generalized supergravity equations are not preserved. Therefore, we suggest modification of these formulas.

Metric algebroid and Dirac generating operator in Double Field Theory

We give a formulation of Double Field Theory (DFT) based on a metric algebroid. We derive a covariant completion of the Bianchi identities, i.e. the pre-Bianchi identity in torsion and an improved generalized curvature, and the pre-Bianchi identity including the dilaton contribution. The derived bracket formulation by the Dirac generating operator is applied to the metric algebroid. We propose a generalized Lichnerowicz formula and show that it is equivalent to the pre-Bianchi identities. The dilaton in this setting is included as an ambiguity in the divergence. The projected generalized Lichnerowicz formula gives a new formulation of the DFT action. The closure of the generalized Lie derivative on the spin bundle yields the Bianchi identities as a consistency condition. A relation to the generalized supergravity equations (GSE) is discussed.

T-folds as Poisson\u2013Lie plurals

In previous papers we have presented many purely bosonic solutions of Generalized Supergravity Equations obtained by Poisson–Lie T-duality and plurality of flat and Bianchi cosmologies. In this paper we focus on their compactifications and identify solutions that can be interpreted as T-folds. To recognize T-folds we adopt the language of Double Field Theory and discuss how Poisson–Lie T-duality/plurality fits into this framework. As a special case we confirm that all non-Abelian T-duals can be compactified as T-folds.

Poisson-Lie plurals of Bianchi cosmologies and Generalized Supergravity Equations

Poisson-Lie T-duality and plurality are important solution generating techniques in string theory and (generalized) supergravity. Since duality/plurality does not preserve conformal invariance, the usual beta function equations are replaced by Generalized Supergravity Equations containing vector mathcal{J} . In this paper we apply Poisson-Lie T-plurality on Bianchi cosmologies. We present a formula for the vector mathcal{J} as well as transformation rule for dilaton, and show that plural backgrounds together with this dilaton and mathcal{J} satisfy the Generalized Supergravity Equations. The procedure is valid also for non-local dilaton and non-constant mathcal{J} . We also show that Div Θ of the non-commutative structure Θ used for non-Abelian T-duality or integrable deformations does not give correct mathcal{J} for Poisson-Lie T-plurality.

Yang–Baxter deformation as an transformation

The rules for Yang–Baxter (YB) deformation for a generic Green–Schwarz string sigma model has been obtained recently. We show that the deformation can be described through the action of a coordinate dependent matrix on the target space fields both in the NS–NS and the RR sectors, generalizing previous results. This enables us to show that the YB deformed fields can be regarded as duality twisted fields in the context of gauged double field theory (GDFT). We compute the fluxes associated with the twist and show that the conditions on the R-matrix determining the YB deformation give rise to conditions for the fluxes on the GDFT side. More precisely, we show that YB deformation is a process which takes a solution of DFT with geometric flux associated with the isometry group G and deforms it to another solution of DFT with vanishing R-flux and non-vanishing Q-flux given by the structure constants of the dual Lie algebra determined by the R-matrix. We also show that the non-unimodularity of the R-matrix forces the generalized dilaton field to pick up a linear dependence on the winding type coordinates of DFT, implying that the corresponding target space fields satisfy the field equations of DFT in the generalized supergravity frame. This provides a new perspective on the relation between the non-unimodularity of the R-matrix, the trace of the Q-flux and the generalized supergravity equations.

Poisson\u2013Lie identities and dualities of Bianchi cosmologies

We investigate a special class of Poisson–Lie T-plurality transformations of Bianchi cosmologies invariant with respect to non-semisimple Bianchi groups. For six-dimensional semi-Abelian Manin triples mathfrak {b}bowtie mathfrak {a} containing Bianchi algebras mathfrak {b} we identify general forms of Poisson–Lie identities and dualities. We show that these can be decomposed into simple factors, namely automorphisms of Manin triples, B-shifts, beta -shifts, and “full” or “factorized” dualities. Further, we study effects of these transformations and utilize the decompositions to obtain new backgrounds which, supported by corresponding dilatons, satisfy Generalized Supergravity Equations.

Non-Abelian T-duality as a transformation in Double Field Theory

Non-Abelian T-duality (NATD) is a solution generating transformation for supergravity backgrounds with non-Abelian isometries. We show that NATD can be de-scribed as a coordinate dependent O(d,d) transformation, where the dependence on the coordinates is determined by the structure constants of the Lie algebra associated with the isometry group. Besides making calculations significantly easier, this approach gives a natural embedding of NATD in Double Field Theory (DFT), a framework which provides an O(d,d) covariant formulation for effective string actions. As a result of this embedding, it becomes easy to prove that the NATD transformed backgrounds solve supergravity equations, when the isometry algebra is unimodular. If the isometry algebra is non-unimodular, the generalized dilaton field is forced to have a linear dependence on the dual coordinates, which implies that the resulting background solves generalized supergravity equations.

Generalized supergravity equations and generalized Fradkin-Tseytlin counterterm

The generalized Fradkin-Tseytlin counterterm for the (type I) Green-Schwarz superstring is determined for background fields satisfying the generalized supergravity equations (GSE). For this purpose, we revisit the derivation of the GSE based upon the requirement of kappa-symmetry of the superstring action. Lifting the constraint of vanishing bosonic torsion components, we are able to make contact to several different torsion constraints used in the literature. It is argued that a natural geometric interpretation of the GSE vector field that generalizes the dilaton is as the torsion vector, which can combine with the dilatino spinor into the torsion supervector. To find the counterterm, we use old results for the one-loop effective action of the heterotic sigma model. The counterterm is covariant and involves the worldsheet torsion for vanishing curvature, but cannot be constructed as a local functional in terms of the worldsheet metric. It is shown that the Weyl anomaly cancels without imposing any further constraints on the background fields. In the case of ordinary supergravity, it reduces to the Fradkin-Tseytlin counterterm modulo an additional constraint.

T -folds from Yang-Baxter deformations

Yang-Baxter (YB) deformations of type IIB string theory have been well studied from the viewpoint of classical integrability. Most of the works, however, are focused upon the local structure of the deformed geometries and the global structure still remains unclear. In this work, we reveal a non-geometric aspect of YB-deformed backgrounds as T -fold by explicitly showing the associated O(D, D; ℤ) T -duality monodromy. In particular, the appearance of an extra vector field in the generalized supergravity equations (GSE) leads to the non-geometric Q-flux. In addition, we study a particular solution of GSE that is obtained by a non-Abelian T-duality but cannot be expressed as a homogeneous YB deformation, and show that it can also be regarded as a T -fold. This result indicates that solutions of GSE should be non-geometric quite in general beyond the YB deformation.

Generalized type IIB supergravity equations and non-Abelian classical r-matrices

We study Yang–Baxter deformations of the superstring with non-Abelian classical r-matrices which satisfy the homogeneous classical Yang–Baxter equation. By performing a supercoset construction, we can get deformed backgrounds. While this is a new area of research, the current understanding is that Abelian classical r-matrices give rise to solutions of type IIB supergravity, while non-Abelian classical r-matrices lead to solutions of the generalized supergravity equations. We examine here some examples of non-Abelian classical r-matrices and derive the associated backgrounds explicitly. All of the resulting backgrounds satisfy the generalized equations. For some of them, we derive ‘T-dualized’ backgrounds by adding a linear coordinate dependence to the dilaton and show that these satisfy the usual type IIB supergravity equations. Remarkably, some of the ‘T-dualized’ backgrounds are locally identical to undeformed after an appropriate coordinate transformation, but this seems not to be generally the case.