This week


Large Conformal Goldstone Mode Fluctuations in the SYK Model

Regular Seminar Alexander Altland (Koeln)

15:00 City U.
room C310

This talk addresses the low energy physics of the Sachdev-Ye-Kitaev model, a paradigm of strongly interacting (Majorana) quantum matter. A salient feature of this system is its exceptionally high degree of symmetry under reparameterizations of physical time. At low energies this symmetry is spontaneously broken and the ensuing infinite dimensional Goldstone mode manifold takes strong influence on all physical observables. We will discuss the effects of these fluctuations on the example of the so-called out of time ordered correlation functions, diagnostic tools to describe both manifestations of quantum chaos in the system and its conjectured duality to an AdS2 gravitational bulk. While previous work predicts exponential decay of these correlations in time our main finding is that at large time scales non-perturbative Goldstone mode fluctuations generate a crossover to power law behavior. This phenomenon must have ramifications in the physics of the holographic bulk which, however, we do not understand at present.


Chiral Algebras for four dimensional N=4 SCFT

Regular Seminar Carlo Meneghelli (Oxford)

13:15 KCL
room K4.31

Any four dimensional N=2 superconformal field theory (SCFT) contains a subsector of local operator which is isomorphic to a two dimensional chiral algebra. If the 4d theory possesses N=3 or N= 4 superconformal symmetry, the corresponding chiral algebra is an extension the N=2 or (small) N=4 super-Virasoro algebra respectively. In this talk I will present some results on the classification of N=4 chiral algebras and discuss if they can correspond to a 4d theory.


Gravity as the square of Yang-Mills: Amplitudes, Symmetries, Equations of Motion

Regular Seminar Alexandros Anastasiou (Nordita)

14:00 QMW
room G.O. Jones 610

Squaring involves the tensoring between the state content of two super Yang-Mills (YM) theories to obtain the state content of a supergravity theory. In the first part of this talk I will discuss how understanding the YM origin of global gravitational symmetries is a powerful tool towards classifying gravity theories which admit such a factorisation. In the second part I will discuss how studying the YM origin of local gravitational symmetries can lead to a field dictionary through which the gravitational equations of motion are derived from the YM ones.


King's Journal Club

Journal Club Rajesh Gupta (KCL)

16:00 KCL
room S4.23

We will discuss "From 3d duality to 2d duality" by Aharony, Razamat and Willett.