Solutions Of Type IIA Supergravity Research Articles

Generalised U-dual solutions via ISO(7) gauged supergravity

We study a solution generating technique in supergravity which can be viewed as a generalised version of U-duality, taking solutions of type IIA supergravity on a 6-sphere with RR flux to new solutions of 11-dimensional supergravity. The new solutions are characterised by an underlying 6-algebra structure. Our construction provides an 11-dimensional uplift of four-dimensional ISO(7) gauged supergravity, using E7 exceptional geometry techniques. We focus on an example where we start with the D2 solution in type IIA supergravity and construct a new frac{1}{2} -BPS 11-dimensional solution.

Non-isometric U-dualities

I study generalisations of U-duality transformations which do not rely on the existence of isometries. I start by providing more details of a recently proposed generalised U-duality map between solutions of type IIA supergravity of the form M7× S3, with NSNS flux, and solutions of 11-dimensional supergravity, in which the three-sphere is replaced by a four-dimensional geometry which encodes three-algebra structure constants. I then show that when M7 admits two abelian isometries, TsT deformations on the IIA side become six-vector deformations in the 11-dimensional setting. These six-vector deformations involve an action of E6(6) on both isometric and non-isometric directions. I discuss the algebraic interpretation of these deformations, and compare and contrast them with (generalised) Yang-Baxter deformations in supergravity.

Generalised U-dual solutions in supergravity

We discuss the notion of generalised U-duality as a solution generating technique in supergravity. We demonstrate a method to take solutions of type IIA supergravity on a 3-sphere, with NSNS flux, to new solutions of 11-dimensional supergravity, using exceptional geometry techniques. These new solutions are characterised by an underlying 3-algebra structure, and generalise features of solutions obtained by non-abelian T-duality, which involve an underlying ordinary Lie algebra. We focus on an example where we start with the pp-F1-NS5 solution in type IIA supergravity. We discuss the properties of our resulting new solution, including the possibility of viewing it globally as a U-fold, and its M2 and M5 brane charges. In the extremal case, the new solution admits an AdS3 limit, which falls into a recently constructed class of M-theory AdS3 backgrounds — this provides a global completion of our solution with a well-defined holographic dual, similar to the global completions of non-abelian T-dual solutions. Our full solution is a 6-vector deformation of this AdS3 limit. We also explicitly solve the Killing spinor equation in the AdS3 limit, finding a frac{1}{2}hbox{-} mathrm{BPS} solution.

Universal pieces of holographic entanglement entropy and holographic subregion complexity

We propose that the definition of holographic subregion complexity (HSC) needs a slight modification for supergravity solutions with warped anti-de Sitter (AdS) factors. Such warp factors can arise due to the nontrivial dilaton profile, for example, in $AdS_6$ solutions of type IIA supergravity. This modified definition ensures that the universal piece of the HSC is proportional to that of the holographic entanglement entropy, as is the case for supergravity solutions without warp factors. This also means that the leading behaviour at large $N$ is the same for both these quantities, as we show for some well-known supergravity solutions (with and without warp factors) in various dimensions. We also show that this relation between the universal pieces suggests "universal" relations between field theoretical analogue of HSC and the sphere partition function or Weyl $a$-anomaly in odd or even dimensions, respectively.

Spin-2 excitations in Gaiotto-Maldacena solutions

In this paper we study spin-2 excitations for a class of N = 2 supersymmetric solutions of type-IIA supergravity found by Gaiotto and Maldacena. The mass spectrum of these excitations can be derived by solving a second order partial differential equation. As specific examples of this class we consider the Abelian and non-Abelian T-dual versions of the AdS5 × S5 and we study the corresponding mass spectra. For the modes that do not “feel” the (non-)Abelian T-duality transformation we provide analytic formulas for the masses, while for the rest we were only able to derive the spectra numerically. The numerical values that correspond to large masses are compared with WKB approximate formulas. We also find a lower bound for the masses. Finally, we study the field theoretical implications of our results and propose dual spin-2 operators.

AdS8 solutions in type II supergravity

We find non-supersymmetric AdS8 solutions of type IIA supergravity. The internal space is topologically an S2 with a U(1) isometry. The only non-zero flux is F0; an O8 sourcing it is present at the equator of the S2. The warping function and dilaton are non-constant. It is also possible to add D8-branes on top of the O8. Possible destabilizing brane bubbles (whose presence would be suggested by the weak-gravity conjecture) are either absent or collapsing. Our solutions are candidate holographic duals to unitary interacting CFTs in seven dimensions with exceptional global symmetry. We also present analogous non-supersymmetric AdSd solutions for general d which are supported only by F0.

Generalized IIB supergravity from exceptional field theory

The background underlying the η-deformed AdS5 × S5 sigma-model is known to satisfy a generalization of the IIB supergravity equations. Their solutions are related by T-duality to solutions of type IIA supergravity with non-isometric linear dilaton. We show how the generalized IIB supergravity equations can be naturally obtained from exceptional field theory. Within this manifestly duality covariant formulation of maximal supergravity, the generalized IIB supergravity equations emerge upon imposing on the fields a simple Scherk-Schwarz ansatz which respects the section constraint.

Holographic flows in non-Abelian T-dual geometries

We use non-Abelian T-duality to construct new N=1 solutions of type IIA supergravity (and their M-theory lifts) that interpolate between AdS_5 geometries. We initiate a study of the holographic interpretation of these backgrounds as RG flows between conformal fixed points. Along the way we give an elegant formulation of non-Abelian T-duality when acting on a wide class of backgrounds, including those corresponding to such flows, in terms of their SU(2) structure.

G-structures and flavouring non-abelian T-duality

We examine non-Abelian T-duality on backgrounds preserving N=1 supersymmetry. We show how backgrounds with SU(3)-structure are mapped to backgrounds with SU(2)-structure. We provide the transformation rules for the corresponding pure spinors. We use these techniques to construct new flavoured solutions of type IIA supergravity.

On the gravity dual of Chern-Simons-matter theories with unquenched flavor

We find solutions of type IIA supergravity which are dual to three-dimensional Chern-Simons-matter theories with unquenched fields in the fundamental representation of the gauge group (flavors). In the holographic dual the addition of flavor is performed by means of D6-branesthat are extended along the Minkowski gauge theory directions and are delocalized in the internal space in such a way that the system is $ \mathcal{N} = 1 $ supersymmetric and the flavor group is abelian. For massless flavors the corresponding geometry has the form of a product space $ Ad{S_4} \times {\mathcal{M}_6} $ , where $ {\mathcal{M}_6} $ is a six-dimensional compact manifold whose metric is obtained by squashing the Fubini-Study metric of $ \mathbb{C}{\mathbb{P}^3} $ with suitable constant factors which depend on the number of flavors. We compute the effect of dynamical quarks in several observables and, in some cases, we compare our results with the ones corresponding to the $ \mathcal{N} = 3 $ supergravity solutions generated by localized flavor branes. We also show how to generalize our results to include massive flavors.

On Type IIA geometries dual to [formula omitted] SCFTs

We provide explicit solutions of Type IIA supergravity which are believed to be dual to N = 2 superconformal four-dimensional gauge theories. These explicit solutions are based on the general ansatz for such a type of backgrounds introduced by Gaiotto and Maldacena.

The completeAdS4×CP3superspace for the type IIA superstring and D-branes

We lift the bosonic AdS_4 x CP^3 solution of type IIA supergravity preserving 24 supersymmetries to a D=10 superspace which has 32 Grassmann-odd directions. The type IIA superspace is obtained from D=11 via dimensional reduction of the coset superspace OSp(8|4)/SO(7) x SO(1,3) by realizing the latter as a Hopf fibration over the former. This construction generalizes to superspace the Hopf fibration of S^7 as a U(1) bundle over CP^3, and is suitable for writing the explicit form of Green-Schwarz-type actions encoding the dynamics of the type IIA string and branes in the AdS_4 x CP^3 superbackground. We show that the OSp(6|4)/U(3) x SO(1,3) supercoset string action describes only a subsector of the complete Green-Schwarz superstring. Thus, even though the superstring equations of motion in the OSp(6|4)/U(3) x SO(1,3) subsector are classically integrable, the fact that the full AdS_4 x CP^3 superspace is not a supercoset requires the use of more general methods to determine whether the superstring in the complete AdS_4 x CP^3 superbackground is classically integrable.

A note on half-supersymmetric bound states in M-theory and type IIA string theory

By using O(7,7) transformations, to deform D6-branes, we obtain half-supersymmetric bound state solutions of type IIA supergravity, containing D6, D4, D2, D0, F1-branes and waves. We lift the solutions to M-theory which gives half-supersymmetric M-theory bound states, e.g. KK6–M5–M5–M5– M2–M2–M2–MW. We also take near-horizon limits for the type IIA solutions, which give supergravity duals of seven-dimensional non-commutative open string theory (with spacetime and space–space non-commutativity), non-commutative Yang–Mills theory (with space–space and light-like non-commutativity) and an open D4-brane theory.

Brane transmutation in supergravity

We study a family of BPS solutions of type IIA supergravity that can be interpreted as describing the `transmutation' of a Neveu-Schwarz five-brane into a D4-brane in the presence of a D6-brane. The D4-brane, which terminates on the D6-brane, can be equally well interpreted as a `pure multipole' configuration of NS5-brane wrapped tightly around the D6-brane. Such a transmutation is a "near-core" version (i.e., near the D6-brane) of the brane-creation that can occur when two branes pass through each other, as in the Hanany-Witten construction. The work below highlights certain charge non-conservation features of type IIA supergravity.

Infinite Lorentz boost along theM-theory circle and nonasymptotically flat solutions in supergravities

Certain nonasymptotically flat but supersymmetric classical solutions of type IIA supergravity can be interpreted as the infinitely boosted version of the $D$ particle solution along the $M$-theory circle. By a chain of $T$-dual transformations, this analysis also applies to yield nonasymptotically flat solutions from the asymptotically flat and (non)extremal solutions with intersecting $D$ strings and $D$ five-branes of type IIB supergravity compactified on a five-torus. Under $S$ duality, the nonasymptotically flat solutions in this context can in particular be used to describe the (1+1)-dimensional Callan-Giddings-Harvey-Strominger type black holes via spontaneous compactifications.

Probing bound states of D-branes

A zero-brane is used to probe non-threshold BPS bound states of ( p, p + 2, p + 4) -branes. At long distances the string calculations agree with the supergravity calculations. The supergravity description is given, using the interpretation of the D = 8 dyonic membrane as the bound state of a two-brane inside a four-brane. We investigate the short distance structure of these bound states, compute the phase shift of the scattered zero-brane and find the bound states' characteristic size. It is found that there should be a supersymmetric solution of type IIa supergravity, describing a bound state of a zero-brane and two orthogonal two-branes, all inside a four-brane, with an additional unbound zero-brane. We comment on the relationship between p-branes and ( p - 2)-branes.