This week

Monday

Emergent diffusion and super-diffusion in quantum and classical chains.

Exceptional Seminar Jacopo de Nardis (University of Ghent)

at:
13:00 KCL
room S5.20
abstract:

Finding a theoretical framework to explain how phenomenological transport laws on macroscopic scales emerge from microscopic deterministic dynamics poses one of the most significant challenges of condensed matter physics. In recent years, the advent of the generalized hydrodynamics in integrable quantum systems and more recent studies of quantum chaos and its relation to transport, reinvigorated the field of nonequilibrium physics in spin chains. Numerous results were found: lower bounds to diffusion constants, exact expressions for diffusion coefficients and remarkable anomalous features of transport in quantum and classical chains, deeply related to the Kardar-Parisi-Zhang dynamical universality class. I will present an overview of such results with a particular focus on anomalous transport and its relation to non-linear hydrodynamics.

Tuesday

TBA

Regular Seminar Elli Pomoni (DESY)

at:
15:00 City U.
room c309
abstract:

Differential operators for superconformal correlation functions

Exceptional Seminar Andrea Manenti (EPFL)

at:
14:00 QMW
room G.O. Jones 610
abstract:

I present a method to expand in components four dimensional superconformal multiplets in N=1 and N=2 superconformal field theories. The method consists in constructing a differential operator for each descendant, which can then be applied on any correlator in superspace. In particular I show how the action on three-point functions can be considerably simplified. An interesting application of the formalism is the proof that N=2 spinning chiral primaries (also called ‘exotic’ primaries) cannot exist in any local SCFT. The interest in constraining this particular kind of operator stemmed from a result in the literature that ruled them out from a very large class of theories. I also discuss the role of the differential operators in the computation of superconformal blocks.

A proposal for the CFT dual for superstrings on ADS3 at the string radius

Regular Seminar Massimo Porrati (New York University)

at:
13:30 IC
room H503
abstract:

After a review of the spectrum of superstrings on the AdS3 WZW background, I will use a conjecture positing the existence of a phase transition, when the AdS radius becomes of order of the string length, to propose a holographic dual CFT that matches exactly the entire continuous spectrum of the superstring. I will conclude with a few observations on the role of interactions amd discrete, short-string states.

Wednesday

TBA

Regular Seminar Sergey Frolov (Trinity College Dublin)

at:
14:00 IC
room H503
abstract:

TBA

Five-Point Functions in N=4 SYM

Regular Seminar Thiago Fleury (International Institute of Physics UFRN)

at:
13:15 KCL
room S2.29
abstract:

The correlation functions (three and higher point) in N=4 SYM can be computed using integrability techniques. One formalism is called hexagonalization and its main object is an integrable form-factor with hexagonal shape. It was successfully used to compute a specific all loop four-point function for the first time. However, it seems that new developments are needed to understand the five-point function and other kinds of finite size corrections. In this talk, after a long review of the hexagonalization procedure, I will explain the five-point calculation at weak coupling and its difficulties.

Thursday

Surface defects in 4d superconformal theories and chiral algebras

Regular Seminar Madalena Lemos (CERN)

at:
14:00 QMW
room G O Jones 610
abstract:

We study symmetry constraints on BPS surface defects in four-dimensional superconformal field theories, showing how supersymmetry imposes relations on anomaly coefficients. Turning to dynamics, we analyze a protected subsector of N=(2,2) surface defects that is captured by a two-dimensional chiral algebra. We discuss how to compute observables of interacting defects from the chiral algebra, including the aforementioned anomaly coefficients.