2021/2022 Web Seminars

This year we will continue our online series of seminars, given last year’s success.

Ordinarily, seminars will take place on Tuesdays at 4PM (CEST/CET). [NB: the time was changed from 2:30PM to 4PM.]

All seminars will take place on Zoom; you can join through the link
(Meeting ID: 876 4300 0411 – Please use your NAME+LAST NAME when logging in to be allowed in the room.)

All seminars will be recorded for your convenience. We will post the link to their archive soon.

You can subscribe to our (Google) calendar using this link:

Fabio and Marco

Seminar Nov 2: Shota Komatsu

On November 2 we will have a seminar by

Shota Komatsu (CERN)

Title: Three tales of de Sitter

I will discuss the fundamentals of quantum field theory on a rigid de Sitter space. First, I will show that the perturbative expansion of late-time correlation functions to all orders can be equivalently generated by a non-unitary Lagrangian on a Euclidean AdS geometry. This finding simplifies dramatically perturbative computations, as well as allows us to establish basic properties of these correlators, which comprise a Euclidean CFT. Second, I use this to infer the analytic structure of the spectral density that captures the conformal partial wave expansion of a late-time four-point function, to derive an OPE expansion, and to constrain the operator spectrum. Third, I will prove that unitarity of the de Sitter theory manifests itself as the positivity of the spectral density. This statement does not rely on the use of Euclidean AdS Lagrangians and holds non-perturbatively.

Meeting information:
November 2, 2021 @ 4:00PM Italian time (CEST)
Zoom Meeting https://l.infn.it/stringwebseminar

Seminar Oct 19: Sergio Benvenuti

On October 19 we will have a seminar by

Sergio Benvenuti (INFN Trieste – SISSA)

Title: Dualities from deconfinement

We prove dualities involving four dimensional N=1 gauge theories with rank-2 matter. We assume only elementary dualities, that is Seiberg and Intriligator-Pouliot dualities. The strategy is to use multiple times elementary S-confining dualities and elementary electric-magnetic dualities, until the desired dual theory is reached. As a first example, we derive the Wess-Zumino description of all S-confining single node quivers with rank-2 matter. As a second example, we derive a ‘fully deconfined’ dual of USp(2N) with an antisymmetric and 2F fundamental fields, then use it to prove a self-duality valid at F=4. These results are based on ongoing work with Stephane Baejot, and uplift 3d results obtained with Ivan Garozzo and Gabriele Lo Monaco.

Meeting information:
October 19, 2021 @ 4:00PM Italian time (CEST) [NOTE the different time wrt previous seminar]
Zoom Meeting https://l.infn.it/stringwebseminar

Seminar Oct 5: Lorenzo di Pietro

On October 5 we will have a seminar by

Lorenzo di Pietro (Università di Trieste)

Title: Conformal boundary conditions for free fields

I will discuss the problem of classifying (interacting) conformal boundary conditions for the simplest bulk conformal field theories: free fields. I will mention concrete examples based on perturbation theory, and then describe results using the numerical conformal bootstrap approach, specifically in the case of a scalar field in four and three bulk dimensions.

Meeting information:
October 5, 2021 @ 2:30PM Italian time (CEST)
Zoom Meeting https://l.infn.it/stringwebseminar

Seminar June 3: X. de la Ossa

On June 3 we will have a seminar by

Xenia de la Ossa (University of Oxford)

Title: The arithmetic of Calabi-Yau manifolds and the black hole attractor mechanism

In this seminar I will introduce the arithmetic of Calabi-Yau 3-folds. An important interest has been to explore whether there are questions of common interest in this context to physicists, number theorists and geometers. The main quantities of interest in the arithmetic context are the numbers of points of the manifold considered as a variety over a finite field. We are interested in the computation of these numbers and their dependence on the moduli of the variety. The surprise for a physicist is that the numbers of points over a finite field are also given by an expression involving the periods of a manifold. The number of points are encoded in the local zeta function, about which much is known in virtue of the Weil conjectures. Especially interesting are the specialisations to singular manifolds, for which the zeta-function manifests modular behaviour. We are also able to find, from the zeta function, black hole attractor points of type IIB supergravity. These correspond to special values of the parameter for which there exists a ten dimensional spacetime for which the 6 dimensions correspond to a CY manifold and the four dimensional spacetime corresponds to an extremal supersymmetric black hole. These attractor CY manifolds are believed to have special number theoretic properties. In fact modular group and modular forms arise in relation to these attractor points. This is joint work with Philip Candelas, Mohamed Elmi and Duco van Straten.

Meeting information:
3rd of June 14:30 Italian Time
Zoom Meeting https://l.infn.it/stringwebseminar

Seminar May 20: M. Scalisi

On May 20 we will have a seminar by

Marco Scalisi (MPI München)

Title: The Gravitino and the Swampland

Abstract: We propose a new swampland conjecture stating that the limit of vanishing gravitino mass corresponds to the massless limit of an infinite tower of states and to the consequent breakdown of the effective field theory. We test our proposal in large classes of models coming from compactification of string theory to four dimensions, where we identify the Kaluza-Klein nature of the tower of states becoming light. We point out a general relation between the gravitino mass and abelian gauge coupling in models with extended supersymmetry, which can survive also in examples with minimal supersymmetry. This allows us to connect our conjecture to other well established swampland conjectures, such as the weak gravity conjecture or the absence of global symmetries in quantum gravity. We discuss phenomenological implications of our conjecture in (quasi-)de Sitter backgrounds and extract a lower bound for the gravitino mass in terms of the Hubble parameter.

Meeting information:
20th of May 14:30 Italian Time
Zoom Meeting https://l.infn.it/stringwebseminar

Seminar May 6: F.Apruzzi

On May 6 we will have a seminar by

Fabio Apruzzi (University of Oxford)

Title: Holography, 1-Form Symmetries and Confinement

Abstract: I will discuss confinement in 4d N = 1 SU(N) Super-Yang Mills (SYM) from holography, focusing on the 1-form symmetry and the holographic realization in terms of the Klebanov-Strassler solution. I will show how from the 5d consistent truncation it is possible to identify the topological couplings that determine the 1-form symmetry (and thus global forms of the gauge group) and its ’t Hooft anomalies. One of the topological couplings corresponds to a mixed 0-1-form symmetry anomaly, which is related to chiral symmetry breaking in the infrared (IR) vacuum. I will also show how to derive this anomaly from the Maldacena-Nunez solution and Little String Theory realizations of pure SYM. I will then discuss how other couplings in the 5d supergravity description of the IR Klebanov-Strassler solution lead to a 4d Topological Field Theory (TQFT) in the boundary, which saturates the mixed anomaly. 

Meeting information:
6th of May 14:30 Italian Time
Zoom Meeting https://l.infn.it/stringwebseminar

Slides are available at

Seminar April 22: S. Razamat

On April 22 we will have a seminar by

Shlomo Razamat (Technion)

Title: SQCD and pairs of pants

Abstract: In this talk we will overview some approaches to study 4d strong coupling phenomena. In particular we will discuss a geometric re-interpretation of N=1 SQCD with special unitary gauge groups. We will argue that the 4d SU(M) SQCD in the middle of the conformal window can be engineered by compactifying certain 6d SCFTs on three punctured spheres.  We will also discuss in this context the interplay between simple geometric and group theoretic considerations and field theoretic strong coupling phenomena. We will show how many known and novel dualities and symmetry emergence phenomena of supersymmetric gauge theories, with  simple and semi-simple  special unitary gauge groups, are related to the Weyl group of $D_{6+2K}$.

Meeting information:
22nd of April 14:30 Italian Time
Zoom Meeting https://l.infn.it/stringwebseminar

You can watch the recording at

Seminar April 8: F. Seibold

On April 8 we will have a seminar by

Fiona Seibold (ETH)

Title: Integrable deformations of superstrings

Abstract: I will give an overview of some recent developments concerning special types of integrable deformations that go under the name of eta (or Yang-Baxter) deformations. Focusing on eta-deformations of the AdS5xS5 superstring, I will explore the fate of Weyl invariance under these deformations and analyse the worldsheet scattering theory of the deformed models.

Meeting information:
8th of April 14:30 Italian Time
Zoom Meeting https://l.infn.it/stringwebseminar

Slides are available at

You can watch the recording at

Seminar March 11: L. Eberhardt

On March 11 we will have a seminar by

Lorenz Eberhardt (IAS)

Title: Summing over geometries in string theory

Abstract: I discuss the question how string theory achieves a sum over bulk geometries with fixed asymptotic boundary conditions. I analyze this problem with the help of the tensionless string on AdS3xS3xT4 (with one unit of NS-NS flux) that was recently understood to be dual to the symmetric orbifold of T4. I argue that large stringy corrections around a fixed background can be interpreted as different semiclassical geometries, thus making a sum over semi-classical geometries superfluous.

Meeting information:
11th of March 14:30 Italian Time
Zoom Meeting https://l.infn.it/stringwebseminar

Slides are available at

You can watch the recording at