Week 24.11.2018 – 02.12.2018


The Cross Anomalous dimension in N=4 super Yang--Mills

Regular Seminar Hagen Munkler (ETH Zurich)

13:15 KCL
room K3.11

The cross or soft anomalous dimension matrix describes the renormalization of Wilson loops with a self-intersection and is an important object in the study of infrared divergences of scattering amplitudes. I will discuss it for the case of the Maldacena--Wilson loop in N=4 supersymmetric Yang--Mills theory, considering both the strong-coupling description in terms of minimal surfaces in AdS5 as well as the weak-coupling side up to the two-loop level. In either case, the coefficients of the cross anomalous dimension matrix can be expressed in terms of the cusp anomalous dimension. The strong-coupling description displays a Gross--Ooguri phase transition and I will argue that the cross anomalous dimension is an interesting object to study in an integrability-based approach.

Reconstructing AdS3/CFT2 correlators

Regular Seminar Rodolfo Russo (QMUL)

14:00 IC
room H503

The AdS/CFT duality maps supersymmetric heavy operators with conformal dimension of the order of the central charge to asymptotically AdS supergravity solutions. I'll show how, by studying the quadratic fluctuations around such backgrounds, it is possible to derive 4-point correlators of two light and two heavy states in the supergravity approximation. Then by using this input, I'll discuss how to reconstruct standard supergravity correlators between four (single particle) operators. I'll present some explicit examples in the AdS3 setup relevant for the duality with the D1-D5 CFT.


Walking, weakly first order phase transitions and complex CFTs

Regular Seminar Bernardo Zan (EPFL Lausanne)

14:00 QMW
room G O Jones 610

I will discuss walking behavior in gauge theories and weakly first order phase transition in statistical models. Despite being phenomena appearing in very different physical systems, they both show a region of approximate scale invariance. They can be understood as a RG flow passing between two fixed points living at complex couplings, which we call complex CFTs. By using conformal perturbation theory, knowing the conformal data of the complex CFTs allows us to make predictions on the observables of the walking theory. As an example, I will discuss the two dimensional Q-state Potts model with Q>4.