Talks

June 19 (Mon)


Time: 09:40 - 10:30 (50min)

Title: Duality invariance in nonlinear SED, N=4 SYM, and higher-spin gauge theories 

Abstract: There exist deep yet mysterious connections between duality invariance and supersymmetry. In particular, models for partial N=2 —> N=1 and N=4 —> N=2 supersymmetry breaking in four dimensions are U(1) duality invariant. This talk will review a program of research, initiated in the late 1990’s, devoted to the construction of nonlinear duality-invariant systems, including a low-energy effective action for N=4 SYM and higher-spin gauge theories.  


Time: 11:00 - 11:50 (50min)

Title: Democracy as a guideline 

Abstract: I will summarize a new democratic approach to field theory, where the electric and magnetic degrees of freedom enter on equal footing.  In particular, a democratic Lagrangian for type II supergravities in 10d will be presented. 


Time: 14:00 - 14:50 (50min)

Title: On the bulk non-locality of Slightly Broken Higher Spin gauge theory 

Abstract: It has been recently argued that Vasiliev higher spin gauge theories are non-local. In this talk we discuss if by breaking higher spin symmetry weakly we can make the theory/ some sector of it local. 


Time: 15:00 - 15:50 (50min)

Title: (Super)spin projection operators

Abstract: In this talk we review the construction of spin projection operators in four-dimensional Minkowski and anti-de Sitter (super)space and study several of their applications. 


Time: 16:20 - 17:10 (50min)

Title: U-duality and Courant Algebroid in Exceptional Field Theory

Abstract: We derive the explicit Courant algebroid anchor for SL(5) and SO(5,5) exceptional field theories. The redefined U-dual exceptional fields derived are governed by the Courant algebroid anchor mapping. In addition, this implies that a U-dual effective exceptional field theory can be introduced with a doubled exceptional field theory indicated.

June 20 (Tue)


Time: 09:40 - 10:30 (50min)

Title: Gauged supergravities and generalized dualities

Abstract: Extended field theories, such as double or exceptional field theory, can be reduced to various gauged supergravities through the generalized Scherk-Schwarz reduction. Focusing on gauged supergravities that can be uplifted to standard ten- or eleven-dimensional supergravities, we provide a general construction of the twist matrix in the Scherk-Schwarz reduction ansatz. We then discuss generalized dualities that extend the Poisson-Lie T-duality. Ordinary Abelian T- and U-duality can be understood as global symmetries of ungauged supergravities, while the generalized dualities can be understood as global symmetries of gauged supergravities. 


Time: 11:00 - 11:50 (50min)

Title: Statistical matter in Double Field Theory

Abstract: In this talk I will explain how to introduce hydrodynamical variables in Double Field Theory (DFT) to include statistical matter, particularly, the perfect fluid. A generalization of the scalar field-perfect fluid correspondence will be explained in detail and with it we will prove, on the one hand, that the perfect fluid dynamics do not receive the alpha'-corrections generated by the generalized Bergshoeff-de Roo identification and, on the other, that a family of O(D,D) invariant string cosmologies can be easily recovered from this model. Since DFT has proved to be useful to deal with both Riemannian and non-Riermannian backgrounds in the last part of the talk I will show the first steps into a non-commutative DFT which can be potentially used to explored non-commutative corrections in these geometries.


Time: 14:00 - 14:50 (50min)

Title: Non-Lorentzian IIB Supergravity

Abstract: We derive the bosonic sector of non-Lorentzian IIB supergravity in two ways: (1) as the non-relativistic string limit of Lorentzian IIB supergravity; and (2) as an effective field theory that is invariant under the appropriate bosonic symmetries, particularly global SL(2,R) and local anisotropic dilatations. In the latter approach, we develop a formalism to make manifest the SL(2,R)-invariance of the theory based on the invariant theory of polynomial equations and binary forms. Unlike the Lorentzian case, the bosonic action in the non-Lorentzian case is fixed by the bosonic symmetries without explicit reference to the fermions or supersymmetry. We, therefore, propose a non-Lorentzian bootstrap, whereby the non-Lorentzian bosonic symmetries are used to fix the bosonic dynamics of the Lorentzian theory. 


Time: 15:00 - 15:50 (50min)

Title: Fractons from non-Riemannian geometry and higher-form symmetries

Abstract: Fracton phases are novel phases of matter that host excitations with restricted mobility. I will discuss two different frameworks for formulating fracton physics. First, I will show that certain gapless fracton phases are realized as a result of spontaneous breaking of continuous higher-form symmetries whose generators do not commute with spatial translations. The mobility restrictions on particle worldlines are fully determined by the underlying symmetry algebra, and we may systematically construct effective field theories which at low energies reduce to known fractonic higher-rank gauge theories. Following this, I will change gears and discuss how key aspects of fracton physics can also be reproduced within the geometric framework of double field theory (DFT). I will argue that the restricted mobility and large degeneracy of quantum states can be attributed to the generalized geodesics and infinite-dimensional isometries present in non-Riemannian backgrounds of DFT. These two systematic approaches to fracton phases enable the engineering of any desired mobility restrictions. To conclude, I will comment on the possibility of a unified understanding of fractons from symmetry and geometry.


Time: 16:20 - 17:10 (50min)

Title: Various Particles from the Coadjoint Orbit 

Abstract: Worldline actions are good toy models for physicists, yet constructing manifestly covariant worldline actions is a tricky work. In this talk, I will show a method for constructing manifestly covariant worldline action using the coadjoit orbit method, while imposing Hamiltonian constraints. Also, I will demonstrate our method to various particles. 

June 22 (Thu)


Time: 09:40 - 10:30 (50min)

Title: Basic curvature and  the Atiyah cocycle in gauge theory 

Abstract: We study connections on higher structures such as Lie and Courant algebroids and their description as differential graded manifolds and explore the role of their basic curvature tensor and of the Atiyah cocycle in topological sigma models and higher gauge theories. 


Time: 11:00 - 11:50 (50min)

Title: Non-invertible (duality) symmetries, topological defects and hamiltonian mechanics 

Abstract:  Non-invertible symmetry is a fairly new concept. It is a generalization of the concept of symmetry between two "phases" A and B which are separated by a "wall" with specific properties, called a topological defect. These concepts appear in many problems of condensed matter and high energy physics. I will talk about my recent research where I explained the physics of topological defects and the corresponding non-invertible symmetries using familiar ideas of hamiltonian mechanics (lagrangian correspondences, in fact), and give applications to string theory, spacetime topology, and integrable structures in Chern-Simons theories. 


Time: 14:00 - 14:50 (50min)

Title: A Simple Constructive Example of Holography 

Abstract: This talk describes the holographic duality between vector model CFT and higher spin gravity. Starting from the CFT we construct the dual higher spin gravity theory. The realization of subregion duality and the holography of information are described in this setting.



Time: 15:00 - 15:50 (50min)

Title: Complex Structures, T-duality and Worldsheet Instantons in Born Sigma Models

Abstract: We investigate doubled (generalized) complex structures in 2D-dimensional Born geometries where T-duality symmetry is manifestly realized. We show that Kahler, hyperkahler, bi-hermitian and bi-hypercomplex structures of spacetime are implemented in Born geometries as doubled structures. We find that the Born structures and the generalized Kahler (hyperkahler) structures appear as subalgebras of bi-quaternions and split-tetra-quaternions. We then study the T-duality nature of the worldsheet instantons in Born sigma models. We show that the instantons in Kahler geometries are related to those in bi-hermitian geometries in a non-trivial way.


Time: 16:20 - 17:10 (50min)

Title: A non-relativistic vivisection of 11-dimensional supergravity

Abstract: Non-relativistic limits of string and M-theory offer a way to (in principle) explore non-relativistic quantum gravity. In this talk I will focus on the realisation of such a limit for 11-dimensional supergravity. Bosonically this results in a non-Lorentzian "membrane Newton-Cartan geometry" with the local tangent space split into three "longitudinal" and eight "transverse" directions, related by Galilean rather than Lorentzian symmetries. Consistency of the limit and its compatibility with local supersymmetry imposes additional constraints on this geometry, and reveals a surprising and intricate non-relativistic supergravity theory in a sense lurking within the (famously unique) relativistic theory. I will explain how this works, and briefly discuss the relationship to the duality web of both relativistic and non-relativistic theories as well as to double and exceptional field theory. Based on 2104.07579 with A. D. Gallegos and N. Zinnato and work in progress with E. Bergshoeff, J. Lahnsteiner and J. Rosseel.

June 23 (Fri)


Time: 09:40 - 10:30 (50min)

Title: Higher-spin gravity in two dimensions

Abstract: A non-abelian higher-spin theory in two dimensions is proposed, describing an infinite multiplet of massive scalar fields,  with fine-tuned masses, interacting with infinitely many topological  gauge fields together with their dilaton-like partners. The corresponding action functional is of BF-type and generalizes the known higher-spin extension of Jackiw-Teitelboim gravity. Finally, we discuss the holographic CFT1 duals of the kinematical structures identified in the AdS2 bulk. 


Time: 11:00 - 11:50 (50min)

Title: On non-Riemannian geometries and singularities in Double Field Theory 

Abstract: Admitting non-Riemannian geometries, Double Field Theory (DFT) extends the notion of spacetime beyond the Riemannian paradigm. In this talk, we will review the non-Riemannian sector of DFT and discuss some of its implications regarding the singularity problem in General Relativity.  


Time: 14:00 - 14:50 (50min)

Title: Conformal higher spin gravity revisited 

Abstract: We will discuss conformal higher spin gravity, an extension of conformal gravity whose spectrum contain conformal higher spin fields of every integer spin. In particular, we will focus on the definition of an action principle for such a theory, and thereby discuss how this problem is related to the deformation quantization of cotangent bundles, the construction of a trace for such a quantization, and the heat kernel of conformally covariant differential operators.