Supersymmetric backgrounds and moduli in generalised geometry

• Daniel Waldram

Room: Aula de conferencias

A generalised approach to consistent truncations

• Michela Petrini

Room: Aula de conferencias We discuss how to formulate consistent truncations with different amount of supersymmetry in the context of generalised geometry and we give some examples.

How to uplift gauged [maximal] supergravities

• Gianluca Inverso

Room: Aula de conferencias I will give the general procedure to construct uplifts of gauged supergravities based on generalised parallelisable spaces (i.e. on generalised Scherk-Schwarz reductions). The existence of uplifts, solutions to the section condition as well as the explicit expressions of the parallelisations are algebraically derived from the embedding tensor of the gauged supergravity. Known examples will be rederived and new applications discussed.

Brane Wess-Zumino terms in String Theory

• Eric Bergshoeff

Room: Aula de conferencias I will present some old and new results on duality-covariant brane Wess-Zumino terms describing their coupling to supergravity background fields. In particular, I will show how this leads to a classification of branes satisfying interesting wrapping rules and to the introduction of so-called exotic branes.

Flatfolds

• Dall'agata Gianguido

Room: Aula de conferencias

Classification of doubled-yet-gauged spacetime

• Jeong-Hyuck Park

Room: Aula de conferencias A classification of the generalized metric in DFT is presented. Analyses on the particle as well as the string dynamics upon the backgrounds are discussed through doubled-yet-gauged sigma models. DFT describes not only Riemannian gravity but also Newton-Cartan gravity, Carroll geometry or chiral string theories, etc. The talk is based on 1707.03713 with Kevin Morand.

Algebraic structures in double and exceptional field theory

• Olaf Hohm

Room: Aula de conferencias

L_infinity algebras and CFT

• Ralph Blumenhagen

Room: Aula de conferencias It is shown that the closure of the infinitesimal symmetry transformations underlying classical (global) W-algebras give rise to L$_\infty$ algebras with in general field dependent gauge parameters. We develop the general formalism for this correspondence and apply it explicitly to the classical W3-algebra. The generalization to the quantum case is discussed as well.

Branes in EFT/DFT, exotic and otherwise

• David Berman

Room: Aula de conferencias

On higher spin representations of K(E10)

• Hermann Nicolai

Room: Aula de conferencias

Affine generalized diffeomorphisms

• Guillaume Bossard

Room: Aula de conferencias

Extended Geometries

• Martin Cederwall

Room: Aula de conferencias We present a unified and completely general formulation of extended geometry, characterised by a Kac-Moody algebra and a highest weight coordinate module. Generalised diffeomorphisms are constructed, as well as solutions to the section constraint. Generically, additional ("ancillary") gauge transformations are present, and we give a concrete criterion determining when they appear. A universal form of the (pseudo-)action determines the dynamics in all cases without ancillary transformations, and also for a restricted set of cases based on the adjoint representation of a finite-dimensional simple Lie group. Our construction reproduces (the internal sector of) all previously considered cases of double and exceptional field theories.

Non-Abelian T-duality in AdS/CFT: the CFT side

• Yolanda Lozano

Room: Aula de conferencias We will discuss recent progress in the understanding of the CFT realization of non-Abelian T-duality when acting on AdS spaces with known CFT duals.

Generalised T-dualities and Integrable Deformations

• Daniel Thompson

Room: Aula de conferencias In this talk I will present an overview of classes of integrable deformations to sigma models known as lambda and eta deformations. I explain the interesting interplay of the these models with generalisations of T-duality involving both non-Abelian isometries and Poisson-Lie symmetry. I will report on recent work considering the quantum aspects of multi-parameter integrable deformations. For the lambda-XXZ model I shall explain how we can implement its quantisation on a light cone lattice as the Heisenberg XXZ spin chain in the gapless regime. For the eta theory with a WZ term we will discuss aspects of its renormalisation and show how it exhibits an interesting self duality under Poisson-Lie symmetries.

Poisson-Lie T-duality in Double Field Theory

• Falk Hassler

Room: Aula de conferencias

Hidden isometry of “T-duality without isometry”

• Ctirad Klimcik

Room: Aula de conferencias We study the T-dualisability criteria of Chatzistavrakidis, Deser and Jonke who recently used Lie algebroid gauge theories to obtain sigma models exhibiting a ``T-duality without isometry''. We point out that those T-dualisability criteria depend on the choice of the algebroid framing. We then show that there always exists an isometric framing for which the Lie algebroid gauging boils down to the standard Yang-Mills gauging recovering thus the traditional isometric non-Abelian T-duality in disguise.

The structure of a DFT algebroid

• Athanasios Chatzistavrakidis

Room: Aula de conferencias In this talk we will discuss some geometric aspects of double field theory. We will argue that the geometric structure of DFT lies in between two pre-Courant algebroids, related to one of them by a projection map and to the other by solving the strong constraint. The structure is not itself a (pre-)Courant algebroid. The proposed picture provides a geometric origin for DFT and its strong constraint, and at the same time it allows for a precise geometric definition of a DFT algebroid.

Membrane sigma models and DFT

• Larisa Jonke

Room: Aula de conferencias Based on the one-to-one correspondence between Courant algebroids and membrane sigma models, we propose a membrane sigma model for double field theory. We discuss the relation of the sigma model to the flux formulation of DFT and show that its gauge symmetries reproduce the structure of a DFT algebroid. In addition, we present some examples that clarify its relation to non-geometric string backgrounds. Finally, we discuss the possibility of relaxing the strong constraint of DFT by allowing for a dynamical fiber metric.

Non-geometric fluxes and non-associativity in M-theory

• Dieter Lust

Room: Aula de conferencias In this talk we discuss non-geometric fluxes in M-theory using exceptional field theory. We will point out that there is a new set of non-geometric fluxes in the R-R sector in the perturbative limit. We show that there are missing momenta conditions, induced by the fluxes. Finally the non-geometric fluxes together with the missing momenta lead to a non-associative phase space, which is related to the non-associative algebra of the octonions.

Locally non-geometric fluxes in M-theory and missing momenta

• Emanuel Malek

Room: Aula de conferencias I will discuss locally non-geometric backgrounds in M-theory. Using duality chains based on twisted tori, I will show that such backgrounds typically have certain missing momentum modes.

The exceptional sigma model

• Chris Blair

Room: Aula de conferencias I will explain the exceptional sigma model, which describes how a string couples to an exceptional field theory background.

Progress in massive IIA holography

• Adolfo Guarino

Room: Aula de conferencias

Universal instabilities of non-susy AdS vacua

• Giuseppe Dibitetto

Room: Aula de conferencias

T-duality transformations along angular directions for the NS5-brane

• Erik Plauschinn

Room: Aula de conferencias I review the uncompactified NS5-brane solution and define in addition to the H-flux a geometric charge for this background. Under T-duality these charge are interchanged, and supersymmetry will be partially broken. These results are compared to the compactified-and-smeared solution, which shows very different behaviour.

Generalized Kinematics and Dynamics for Double Field Theory

• Felix Rudolph

Room: Aula de conferencias Double Field Theory can be formulated on a 2d-dimensional para-Hermitian manifold ($P,\eta,\omega$) by supplementing the $O(d,d)$ metric $\eta$ with an almost symplectic two-form $\omega$. Together $\eta$ and $\omega$ provide a bi-Lagrangian splitting of the tangent bundle TP into two Lagrangian subspaces. I will sketch how to construct a canonical connection and a corresponding generalized Lie derivative for the Leibniz algebroid on TP. Under certain integrability conditions the symmetry algebra closes for general $\eta$ and $\omega$, even when they are not flat and constant. This provides a generalization of the kinematical structure of DFT. By including the generalized metric $H$ into the setup - which thus becomes para-quaternionic - we can construct a connection compatible with all three structures ($\eta, \omega, H$) and thus can also generalize the dynamics. The precise relation between DFT and generalized geometry is also discussed.

Supersymmetric brane field theories and non-linear instantons on curved backgrounds

• Hagen Triendl

Room: Aula de conferencias In recent years supersymmetric field theories have been realized on large classes of curved backgrounds, by coupling them to off-shell supergravity backgrounds. I will describe how these field theories are realized in string theory on D-branes in flux backgrounds, and how the auxiliary fields of off-shell supergravity can be matched with the various fluxes of string theory. Finally I will discuss how linear and non-linear supersymmetries and their instantons can be described by using an R-symmetry covariant description.

Moduli mass hierarchy in non-geometric flux compactifications

• Oscar Loaiza-Brito

Room: Aula de conferencias We study some conditions on which there is a hierarchy on the moduli masses on a type IIB tori compactification in the presence of non-geometrical fluxes.

Let’s talk about winding modes again

• Martin Mayo

Room: Aula de conferencias DFT was, at the beginning, created to incorporate the windings modes and in this way get stringy features in a field theory. But then section condition appeared and all the motivation was lost. In this talk I will speak about new ways of incorporating windings and going beyond the section condition, taking advantage of the enhancement property of string theory.

A DFT O(d,d,Z) invariant action including (some) winding modes

• Yago Cagnacci

Room: Aula de conferencias

Duality in Convex Optimization: Application to Minimal Area Surfaces

• Barton Zwiebach

Room: Aula de conferencias We define convex programs and describe the construction of dual programs. After explaining the key results of this theory (max-flow min-cut, strong duality, complementary slackness, etc) we apply the methods to find unknown genus one minimal area surfaces.

Non-geometric Calabi-Yau backgrounds

• Chris Hull

Room: Aula de conferencias

TBA

• Charles Strickland Constable

Room: Aula de conferencias

AdS classifications

• Alessandro Tomaseillo

Room: Aula de conferencias I will review recent classification results about AdS$_d$ compactifications in various dimensions. While the efforts in $d>4$ were originally motivated by holography, several examples should be useful for flux compactifications, for example because of the simultaneous presence of back-reacted sources of different types. In AdS$_7$ we now have a one-line description of all possible solutions. In AdS$_5$ a large class is related to AdS$_7$ by compactification; among these, some interesting examples with ``punctures'' are starting to emerge. Finally, I will talk about classifying AdS$_4$ solutions with extended supersymmetry.

Supersymmetry and geometry of stringy corrections

• Ruben Minasian

Room: Aula de conferencias I’ll try to review why there are still open questions (that we should care about) concerning the structure of stringy corrections to low energy effective actions and if/how generalised geometry can help to answer these.

Is String Phenomenology an Oxymoron?

• Fernando Quevedo

Room: Aula de conferencias