Featured

Web seminars launch and calendar

In view of the ongoing Coronavirus pandemic we have decided to start an on-line series to continue our scientific exchange in spite of the adversities.

Ordinarily seminar will take place on Thursdays at 14:30 Italian time.

The seminars are organised through Zoom meetings, and it is possible to join through the link
https://l.infn.it/stringwebseminar
(Meeting ID: 198 435 430 )

You can subscribe to our (Google) calendar using this link:
https://bit.ly/2y5NzNZ

Alessandro and Domenico

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

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
https://pandora.infn.it/public/348d2f

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
https://pandora.infn.it/public/43f4de

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
https://pandora.infn.it/public/28e194

You can watch the recording at
https://pandora.infn.it/public/e73a36

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
https://pandora.infn.it/public/95b99e

You can watch the recording at
https://pandora.infn.it/public/00cf45

Seminar February 25: P.A. Grassi

On February 25 we will have a seminar by

Pietro Antonio Grassi (Università del Piemonte Orientale)

Title: The power of integral forms in supersymmetric field theories

Abstract: We present the power of a geometric framework for supergravity and supersymmetric theories solely based on differential calculus on supermanifolds. The relevant field theory Lagrangians are expressed by integral forms, ready to be integrated on the full supermanifold and automatically implementing the invariance  under super-diffeomorphisms. We show that different superspace formulations of a given theory arise from  the same action upon suitable choices of the integral forms. We also show the analogies with algebraic structures in string field theory and several new results. 

Meeting information:
25th of February 14:30 Italian Time
Zoom Meeting https://zoom.us/j/19843543

Slides are available at
https://pandora.infn.it/public/6b04f5

You can watch the recording at
https://pandora.infn.it/public/970e42

Seminar February 11: N. Gaddam

On February 11 we will have a seminar by

Nava Gaddam (Utrecht)

Title: The black hole eikonal and the information paradox

Abstract: In this talk, I will show that there is a remarkable phase of quantum gravity (which we will call the ‘black hole eikonal’ phase) where gravitational collision energies near the horizon satisfy E >> \gamma M_Pl, with \gamma = M_Pl/M_BH. I will argue that this regime captures gravitational scattering with impact parameters smaller than the Schwarzschild radius. Scattering amplitudes are unitary suggesting a resolution of the information paradox; I will sketch the explicit derivation of the 2-2 amplitude for massless scalars, non-perturbatively in \gamma. Owing to the low energies of collisions, there are no firewalls experienced by infalling observers. A consequence of these results is that the information paradox is an emergent one at low energies and does not require detailed ultra-violet physics for a resolution. 

Meeting information:
11th of February 14:30 Italian Time
Zoom Meeting https://zoom.us/j/19843543

You can watch the recording at
https://pandora.infn.it/public/be3ca2

Seminar January 28: L. Rastelli

On January 28 we will have a seminar by

Leonardo Rastelli (Stony Brook University)

Title: A CFT distance conjecture

Abstract:
We formulate a series of conjectures relating the geometry of conformal manifolds to the spectrum of local operators in conformal field theories in d > 2 spacetime dimensions. Our central conjecture is that all theories at infinite distance in the Zamolodchikov metric possess an emergent higher-spin symmetry, generated by an infinite tower of currents whose anomalous dimensions vanish exponentially in the distance. In the holographic context our conjectures are related to the Distance Conjecture in the swampland program. We motivate and illustrate these conjectures by surveying the landscape of superconformal field theories in three and four dimensions.

Meeting information:
14th of January at 14:30 Italian Time
Zoom Meeting https://zoom.us/j/19843543

You can watch the recording at
https://pandora.infn.it/public/32a276

Seminar January 14: M. Henneaux

On January 14 we will have a seminar by

Marc Henneaux (ULB & Collège de France)

Title: Asymptotic symmetries of electromagnetism and gravity: a Hamiltonian study

Abstract: The asymptotic symmetries of gravity and electromagnetism are remarkably rich.    The talk will explain the asymptotic structure of these theories in the asymptotically flat case by making central use of the Hamiltonian formalism.  In particular, how the relevant infinite-dimensional asymptotic symmetry groups emerge at spatial infinity will be discussed. Extensions to supergravity will be briefly touched upon.

Meeting information:
14th of January at 14:30 Italian Time
Zoom Meeting https://zoom.us/j/19843543

Slides are available at
https://pandora.infn.it/public/c8b1b7

You can watch the recording at
https://pandora.infn.it/public/06173b