We construct a plethora of type-II supergravity solutions featuring AdS factors in their geometries, derived from integrable deformations of coset CFTs. Specifically, we uplift the $\textit{λ}$-deformed models of SO(4) $\textit{/}$SO(3) and SO(5) $\textit{/}$SO(4) , including the non-compact version of the latter. Requiring reality for the backgrounds imposes bounds on the deformation parameter. As a result, some of the solutions do not admit non-Abelian T-dual limit.

Germany

Georgios Itsios

Type-II backgrounds from deformed coset CFTs

We construct a generalisation of the -deformation of the Principal Chiral Model (PCM) where we deform just a subgroup of the full symmetry group . We find that demanding Lax integrability imposes a crucial restriction, namely that the coset must be symmetric. Surprisingly, we also find that (when is non-abelian) integrability requires that the term in the action involving only the spectator fields should have a specific -dependence, which is a curious modification of the procedure expected from the known = case. The resulting Lax connection has a novel analytical structure, with four single poles as opposed to the two poles of the cases of the PCM and of the standard -deformation. We also explicitly work out the example of = SU(2) and = U(1), discussing its renormalisation group flow to two loops.

Spain

Riccardo Borsato

J. Miramontes

Greece

Konstantinos Siampos

Integrability of the

We construct the embedding of the λ-model on SL(2, ℝ) × SU(2) × SU(2) in type-II supergravity. In the absence of deformation, the ten-dimensional background corresponds to the near-horizon limit of the NS1-NS5-NS5 brane intersection. We show that when the deformation is turned on, supersymmetry breaks by half, and the solution preserves 8 supercharges. The Penrose limits along two null geodesics of the deformed geometry are also considered. It turns out that none of the associated plane-wave backgrounds exhibit supernumerary supercharges.

Supersymmetric solutions of type-II supergravity from λ-deformations and zoom-in limits

We provide the first supersymmetric embedding of an integrable λ-deformation to type-II supergravity. Specifically, that of the near horizon of the NS1-NS5 brane intersection, geometrically corresponding to AdS 3 × S 3 × T 4. We show that the deformed background preserves 1/4 of the maximal supersymmetry. In the Penrose limit we show that it preserves no-more than one half of the maximal supersymmetry.

Konstantinos Sfetsos

Supersymmetric backgrounds from λ-deformations

We generalize the Mellin representation for a generic co-dimension flat defect CFT. We study the analytic structure of the Mellin amplitudes. We also compute Witten diagrams for a generic co-dimension flat defect CFT.

Brazil

Portugal

Vasco Goncalves

A note on defect Mellin amplitudes

We construct and thoroughly study a new integrable example of the AdS/CFT correspondence with Schrödinger symmetry. On the gravity side, the supergravity solution depends on two parameters and is obtained by marginally deforming the internal space of the Schrödinger background through a series of TsT transformations. On the field theory side, we identify the dual field theory which also depends on two parameters.

George Georgiou

United States

Dimitrios Zoakos

Marginally deformed Schrödinger/dipole CFT correspondence

Kerr–Schild perturbations in General Relativity provide a fruitful way of constructing new exact solutions starting from known ones, elucidating also the structure of the spacetimes. We initiate such a study in the context of string theory and supergravity. Specifically, we explicitly construct Kerr–Schild perturbations of coset CFTs based on low dimensionality orthogonal groups. We show that these give rise to scale, but not Weyl, invariant integrable σ-models. We explicitly demonstrate that these models can also be derived from a particular limiting procedure of λ-deformed coset CFTs based on non-compact groups. The target space of the simplest σ-model describes a two-dimensional scale invariant black hole for which we also provide two different embeddings to type-II supergravity.

Kerr–Schild perturbations of coset CFTs as scale invariant integrable -models

A novel class of integrable σ-models interpolating between exact coset conformal field theories in the IR and hyperbolic spaces in the UV is constructed. We demonstrate the relation to the asymptotic limit of λ-deformed models for cosets of non-compact groups. An integrable model interpolating between two spacetimes with cosmological and black hole interpretations and exact conformal field theory descriptions is also provided. In the process of our work, a new zoom-in limit, distinct from the well known non-Abelian T-duality limit, is found.

Novel integrable interpolations

We elevate λ-deformed σ-models into full type-II supergravity backgrounds. We construct several solutions which contain undeformed <math><mi>A</mi><mi>d</mi><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub></math> spaces, with <math><mi>n</mi><mo>=</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>,</mo><mn>4</mn></math> and 6, as an integrable part. In that respect, our examples are the first in the literature in this context and bring λ-deformations in contact with the AdS/CFT correspondence. The geometries are supported by appropriate dilaton and RR-fields. Most of the solutions admit non-Abelian T-dual limits.

Solutions and -deformations

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 × S 5 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.