• Marcelo Oyarzo (UdeC/PoliTo): Black Holes in the STU Model of Gauged D=4 N=8 SUGRA

The N=8 SO(8) gauged SUGRA in D=4 corresponds to the low-energy dynamics of M-theory when it is compactified on an S^7. A great effort has been put into the construction of solutions of consistent truncations of the maximal theory, such as the STU model. In this talk, I will review the supersymmetric and non-supersymmetric black hole solutions known in the literature, putting special attention on the static planar black hole configurations with four charges. For the latter family, I will present a new thermodynamic stability analysis that can be performed as the state equation can be found analytically. 

• Lucía Cabrera (Instituto Balseiro): Of stringy field theories and hidden symmetries

In a recent article, our group proposed an effective action that successfully incorporates stringy features into a field theory framework. A key example of these features is gauge symmetry enhancement, which occurs at specific points in moduli space in the context of toroidal compactifications of the heterotic string. By writing each field in terms of a double set of coordinates, as suggested by Double Field Theory (DFT), the action becomes background-independent and is endowed with a non-abelian structure through a non-commutative product. The moduli space only becomes apparent when performing a generalized mode expansion on the Lagrangian, which then reproduces different symmetry enhancements, effectively interpolating among gauge theories.

In this talk, we will delve into this construction and examine the transformation laws for the fields that lead to an invariant interpolating action. We will also discuss how these laws, when mode-expanded, encompass the usual gauge transformations.

Based on  arXiv:1805.10306 [hep-th]

• Joaquin Liniado (Instituto de Física La Plata): Gauge Theory and Integrability 

In this talk I will present an overview of the correspondence between holomorphic Chern-Simons theories and integrable models, as introduced in the seminal work of Costello, Witten and Yamazaki. Employing techniques from twistor theory and higher categories, I intend to describe how integrable models in different dimensions may be constructed. This talk is based in [2407.09479], [2405.18625], [2311.17551]. 

• Robinson Mancilla (University of California, Santa Barbara): A derivation of the Smarr formula for AdS black holes from an effective action

The Smarr relation in AdS black hole thermodynamics is a natural generalization of the Euler equation in traditional thermodynamics. We show that the Smarr relation applies not only to AdS black holes but also to any perfect fluid living in a spacetime with a compact spatial section. This result follows naturally from an effective action that includes the size of the compact space as a thermodynamic variable, resulting in the Euler equation plus a finite size correction from where we recognize the Smarr formula. In this manner, the Smarr formula is consistent with standard ideas of Gauge/Gravity duality. Additionally, we verify the thermodynamic relations without varying the cosmological constant $\Lambda$ or Newton's constant $G_N$ for the case of the AdS Reissner-Nordström black hole. Consequently, our results argue against the proposal of extended black hole thermodynamics, where the variation of the cosmological constant is proportional to a certain thermodynamic variable.

• Martin Lagares (National University of La Plata): Bootstrapping line operators in AdS3/CFT2

Since the early days of AdS/CFT, line operators have played a crucial role in the study of holographic dualities. Being a convenient framework for the analysis and development of non-perturbative techniques, line operators have provided many non-trivial tests of AdS5/CFT4 and AdS4/CFT3. However, much less is known about the characteristics of these operators in the context of the lower dimensional AdS3/CFT2. In this talk I will discuss the results of an upcoming paper with G. Bliard, D. Correa and I. Salazar-Landea, where we study 1/2 BPS line defects in the holographic dual of type IIB string theory in AdS3xS3xT4 with mixed R-R and NS-NS flux. We use analytic conformal bootstrap to compute the four-point functions of the displacement supermultiplet up to next-to-leading order in the strong coupling expansion, and we find agreement with the expectations obtained from a Witten diagram computation.

• Kristiansen Lara (Centro de Estudios Científicos): Stealth construction and its thermodynamic imprints

In the new era of gravitational discoveries, a theoretical possibility for uncovering new physics is the introduction of scalar fields. One of them, identified almost two decades ago, are stealths; a nontrivial configuration that renders a vanishing energy-momentum tensor. They generate no backreaction in the spacetime, yielding an effective vanishing equation of motion for the gravitational field, forgoing the sourcing of the stress-energy tensor. 

The objective of this talk is threefold: (1) After reviewing their existence within different backgrounds, set-ups and couplings, we propose a new path on their construction, applied in the nonminimal case. Consequences of this approach and extensions are analyzed. (2) To apply the latter approach to recover and generalize examples of the literature, and find novel stealth configurations. (3) To elucidate their role and implications for black hole thermodynamics. 

• Alejandro Rodriguez (Universidad de Buenos Aires): Aspects of Conformal Gravity and Double Field Theory from a Double Copy Map

Double Field Theory (DFT) can be constructed as the double copy of a Yang-Mills theory. In this work we extend this statement by including higher derivative terms. Starting from a four-derivative extension of Yang-Mills whose double copy is known to correspond to a conformal-gravity theory, we obtain a four-derivative theory formulated in double space, which in the pure gravity limit reduces to conformal gravity at quadratic order. This result reveals important aspects for the study of conformal symmetry in the context of DFT through double copy maps.

link: https://arxiv.org/abs/2307.14538

• Facundo Rost (University of Amsterdam): A New Twist on Spinning (A)dS Correlators 

Massless spinning correlators in cosmology are extremely complicated. In contrast, the scattering amplitudes of massless particles with spin are very simple when written in convenient variables. In this talk I will show that all kinematic constraints of cosmological correlators can be made manifest by writing them in twistor space, which exposes their hidden simplicity. Based on https://arxiv.org/abs/2408.02727, together with Daniel Baumann, Grégoire Mathys and Guilherme L. Pimentel.

• Sergio Ernesto Aguilar Gutierrez (KU Leuven): Pushing boundaries with the double-scaled SYK model: TTbar deformations, thermodynamics, and Krylov complexity

Explicit examples of the holographic duality outside the anti-de Sitter (AdS) space/conformal field theory (CFT) correspondence are relatively scarce and, arguably, not well-understood. However, low-dimensional quantum gravity allows new opportunities to explore holography for geometries with different metrics and asymptotic boundary conditions with respect to AdS space. In particular, the double scaled SYK model (DSSYK) has catalyzed new developments in non-AdS holography, as its dual bulk geometry contains regions of both positive and negative Ricci curvature, having both black hole and cosmological horizons; and is described by a dilaton-gravity theory with a Sin Phi. We study TTbar-deformations in the DSSYK model after performing the ensemble averaging to probe the thermodynamics and quantum information observables associated with the regions of positive curvature, which allows for an approximate description of 2-dimensional de Sitter (dS) space with an explicit quantum mechanical model at arbitrary high energies. We study the structure of the Hilbert space of the deformed DSSYK model, and transfer matrix using the finite cutoff interpretation of the TTbar-deformation. By placing the DSSYK model in the stretched horizon of the dual geometry with a positive and nearly constant scalar curvature, we realize the stretched horizon proposal of Susskind. We evaluate the conditions for the energy spectrum of the deformed system to be well defined, and for the system to be thermodynamically stable. We study quantum information properties of the deformed model, including Krylov complexity for states and operators, and entanglement entropy for a bipartition of the system, which show close similarity with those expected in stretched horizon holography.