Week 09.12.2024 – 15.12.2024

Gauge (or Yang-Mills) theories are the building blocks of our current physical understanding of the universe. In parallel, string theory is a framework for a consistent quantum description of gravity. Gauge-String duality a.k.a. the AdS/CFT correspondence proposes a remarkable connection between these two very different classes of theories. I will begin by discussing why it is important to arrive at a first principles understanding of the underlying mechanism of this duality relating quantum field theories (QFTs) and string theories (or other theories of gravity). I will then proceed to discuss a very general approach which aims to relate large N QFTs and string theories, starting from free field theories. This corresponds to a tensionless limit of the dual string theory on AdS spacetime. Finally, I will discuss specific cases of this limit for 3d AdS (dual to 2d CFT) and 5d AdS (dual to 4d Super Yang-Mills theory), where one has begun to carry this program through to fruition, going from the string theory to the field theory and vice versa.

There are various ways of constructing 5d SCFTs in String Theory; most famously, one can look at geometric engineering in M-theory or webs of 5-branes in type IIB. It is well understood how to translate from one setup to the other in the case where the Calabi-Yau geometry is toric. However, in the type IIB picture, brane manipulations such as Hanany-Witten transitions can lead us beyond the pure toric context; the combinatorial data enconding the system has been dubbed a Generalized Toric Polygon (GTP). In this talk, I will discuss recent progress understanding the geometry of GTPs. A key role is played by the mirror Calabi-Yau, where Hanany-Witten transitions take a very simple form. This allows us to make contact with a mathematical notion of "polytope mutation", and import part of the results in that literature to our physical setup; as an example, we find "mutation invariants" that can prove useful in the classification of 5d SCFTs. Time permitting, I'll also discuss some consequences for the BPS quivers of the 5d theories engineered by GTPs.

15:00 - Jeremy Mann: "Semiclassical N-body Problem in AdS at Large Spin" // 15:20 - Azadeh Maleknejad: "Stochastic Fermion Creation: Remnant of Gravitational Chiral Anomaly" // 15:40 - Refreshments // 16:10 - Ofer Lahav (UCL): "The Status of Dark Energy Observations" // 17:00 - Pub