Category: Seminar

Seminar Jul 7: Pietro Benetti Genolini

On July 7 we will have a seminar by

Pietro Benetti Genolini (King’s College London)

Title: Complex saddles and black holes in AdS4

Abstract:

The large-N limit of the superconformal index of ABJM theory is related to black holes that are asymptotically AdS4. The relation can be made more precise by mapping the index to a supersymmetric partition function on a twisted S1 x S2 background, whose large-N limit corresponds to the on-shell action of supersymmetric black hole solutions with appropriate boundary conditions. When computing the large-N limit of the partition function, we encounter a family of complex saddles labelled by an integer. In this talk, I will consider the gravitational dual of these complex saddle points.

Meeting information:
July 7, 2022 @ 2:30PM Italian time (CEST)
Zoom Meeting https://l.infn.it/stringwebseminar

This will be a hybrid meeting, taking place in room U2-02 of the University of Milan-Bicocca (building U2, ground floor) in Milan and streamed on Zoom. All are welcome to attend in person.

You can watch the recording at the link https://pandora.infn.it/public/pietro-benetti_genolini.

Seminar Mar 15: Mithat Ünsal


On March 15 we will have a seminar by

Mithat Ünsal (North Carolina State)

Title: Adiabatic continuity, mixed anomalies and semi-classical
description of confinement

Abstract:

I describe an  anomaly-preserving compactification of four dimensional gauge theories, including Yang-Mills theory, its supersymmetric version and QCD, down to 2d by turning on ‘t Hooft flux through a 2-torus. This provides a new framework to analytically calculate nonperturbative properties such as confinement, chiral symmetry breaking, and multi-branch structure of vacua. We give the semiclassical description of these phenomena based on the center vortices, and show that it enjoys the same anomaly matching condition with the original 4d gauge theory. For YM, the long distance theory maps to TQFT deformed by local topological operators. We conjecture that the weak-coupling vacuum structure on small T2 x R2 is adiabatically connected to the strong-coupling regime in infinite volume without any phase transitions.

Meeting information:
March 15, 2022 @ 4:00PM Italian time (CET)
Zoom Meeting https://l.infn.it/stringwebseminar

You can watch the recording at the link https://pandora.infn.it/public/mithat-unsal.

Seminar Mar 1: Gabriel Cuomo


On March 1 we will have a seminar by

Gabriel Cuomo (SCGP)

Title: Line defects in CFTs: renormalization group flows and semiclassical limits

Abstract:

I will discuss line defects in d-dimensional Conformal Field Theories (CFTs). I will first review recent general results on the monotonicity of defect RG flows for line defects. I will then discuss three physically interesting examples of line defects: magnetic field defects, spin impurities, and Wilson lines. In particular, I will present a recently developed semiclassical approach, which allows studying spin impurities and Wilson lines in large representations.

Meeting information:
March 1, 2022 @ 4:00PM Italian time (CET)
Zoom Meeting https://l.infn.it/stringwebseminar

You can watch the recording at the link https://pandora.infn.it/public/gabriel-cuomo.

Seminar Feb 15: Riccardo Argurio


On February 15 we will have a seminar by

Riccardo Argurio (ULB)

Title: SUSY breaking in branes at singularities (or: The octagon rising from the swamp)

Abstract:

After motivating the search for string theory configurations where supersymmetry is spontaneously broken, I will discuss the approach focused on branes at singularities, in the context of the open/closed duality (a.k.a. gauge/gravity correspondence). The search for SUSY breaking configurations is made difficult by the peculiarities of the QFT models of dynamical SUSY breaking models one wants to reproduce with branes, and by the instabilities inherent with the brane construction. I will finally present a configuration, based on a particular singularity (which we dubbed the Octagon), that is the only one to pass all the stability tests. We comment on its properties and possible generalizations, and geometric/supergravity realizations. We will make some comments on the relevance of our results for some Swampland conjectures.
Based on 1909.04682, 2005.09671, 2007.13762, 2009.11291 + work in progress.

Meeting information:
February 15, 2022 @ 4:00PM Italian time (CET)
Zoom Meeting https://l.infn.it/stringwebseminar

You can watch the recording at the link https://pandora.infn.it/public/riccardo-argurio.

Seminar Feb 1: Carlo Maccaferri

On February 1 we will have a seminar by

Carlo Maccaferri (Torino)

Title: Integrating out in string field theory: effective actions and background independence

Abstract:
I review recent results on the procedure of integrating out unwanted degrees of freedom from a fundamental microscopic string field theory action. A first application is the construction of effective actions/potentials for the strings’ light fields by integrating out massive string fields.  I will give a few examples of D-branes effective potentials obtained in this way. A second, physically different, application concerns analytic classical solutions of open string field theory (OSFT) describing generic D-brane systems in a given closed string background. This time, by integrating out peculiar “pure gauge” degrees of freedom, we can precisely relate the action for fluctuations on the classical solution to the OSFT directly formulated on the new background thus explicitly realizing (open string) background independence. I end up discussing possible new directions for future explorations.

Meeting information:
February 1, 2022 @ 4:00PM Italian time (CET)
Zoom Meeting https://l.infn.it/stringwebseminar

You can watch the recording at the link https://pandora.infn.it/public/carlo-maccaferri.

Seminar Nov 30: Natalia Pinzani-Fokeeva

On November 30 we will have a seminar by

Natalia Pinzani-Fokeeva (MIT & University of Florence)

Title: Enstrophy and black hole supertranslations

Abstract: Enstrophy is an approximately conserved quantity in 2+1 dimensional fluid flows that has dramatic consequences for the phenomenology of nonrelativistic turbulence: it implies an inverse energy cascade. In this talk, I will present an algorithm on how to construct an enstrophy current for generic fluid flows (relativistic and non). In addition, I will show how a subset of certain horizon symmetries of 3+1 dimensional AdS black holes also lead to enstrophy conservation in the dual holographic fluid theory.

Meeting information:
November 30, 2021 @ 4:00PM Italian time (CET)
Zoom Meeting https://l.infn.it/stringwebseminar

You can watch the recording at the link https://pandora.infn.it/public/natalia-pinzani-fokeeva.

Seminar Nov 2: Shota Komatsu

On November 2 we will have a seminar by

Shota Komatsu (CERN)

Title: Three tales of de Sitter

Abstract:
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 (CET)
Zoom Meeting https://l.infn.it/stringwebseminar

You can watch the recording at the link https://pandora.infn.it/public/shota-komatsu.

Seminar Oct 19: Sergio Benvenuti



On October 19 we will have a seminar by

Sergio Benvenuti (INFN Trieste – SISSA)

Title: Dualities from deconfinement

Abstract:
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 Stéphane Bajeot, 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

You can watch the recording at the link https://pandora.infn.it/public/sergio-benvenuti.

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

Abstract:
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

You can watch the recording at the link https://pandora.infn.it/public/lorenzo-dipietro.

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

Abstract:
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