Titles and Abstracts

Till Bargheer

"Handling Handles -- Non-Planar AdS/CFT Integrability"

I will explain how non-planar corrections to correlation functions in

N=4 super Yang-Mills theory can be computed via the recently developed

integrability-based method of hexagonalization.

Reference: https://arxiv.org/abs/1711.05326

Benjamin Basso

"Hexagons Form Factors and Feynman Integrals"

I will review the recent progress at describing correlators in N=4 SYM theory using integrable methods, and most notably the approach based on the so-called hexagon form factors. After introducing the main ideas and results, I will discuss recent applications to the calculations of certain multi-loop Feynman graphs in massless phi^4 theory.

Jacob Bourjaily

"Improving Integrands & Integrals for Amplitudes"

There have been enormous advances in both our ability to represent scattering amplitudes at the integrand-level (for an increasingly wide variety of quantum field theories), and also in our integration technology (and our understanding of the functions that result). In this talk, I review both sides of these recent developments. At the integrand-level, I describe the "prescriptive" refinement of generalized unitarity, and show how closed, integrand-level formulae can be given for all leading-weight contributions to any amplitude in any quantum field theory. Regarding integration, I describe some new results that could be summarized as "dual-conformal sufficiency": that all planar, ultraviolet-finite integrands can be regulated and computed directly in terms of manifestly dual-conformal integrals. I illustrate the power of having such representations, and discuss the role played by a (conjectural) cluster-algebraic structure for kinematic dependence.

Garrett Goon

"Partially Massless Fields During Inflation"

The particle spectrum of de Sitter is different from that of flat space. There exist special, discrete states in dS whose behavior lies somewhere between that of the massive and massless fields we are familiar with in Minkowski. I will discuss the signatures that such "Partially Massless" fields would leave on inflationary correlators, highlighting particularly clean detection channels. The calculation will be phrased in terms of the "Wavefunction of the Universe", a practical tool for computing expectation values whose construction mirrors standard holographic methods.

Paul Heslop

"Quantum Gravity from Conformal Field Theory"

AdS/CFT relates certain correlation functions in N=4 SYM to supergravity amplitudes in AdS space. In this talk I give an outline of recent progress in which we use this duality together with CFT bootstrap techniques to obtain

one loop quantum gravity amplitudes. Along the way we need to resolve a large N degeneracy of double trace operators and as a byproduct of our investigations obtain the leading corrections to the anomalous dimensions of all double trace operators of supergravity bound states. I will also discuss M theory corrections and data for the M5 brane world volume theory.

Gregory Korchemsky

"Instanton effects in correlation functions in N=4 SYM on the light-cone"

We study instanton corrections to four-point correlation correlation function of half-BPS operators in N=4 SYM in the light-cone limit when operators become null separated in a sequential manner. We exploit the relation between the correlation function in this limit and light-like rectangular Wilson loop to determine the leading instanton contribution to the former from the semiclassical result for the latter. We verify that the light-like rectangular Wilson loop satisfies anomalous conformal Ward identities nonperturbatively, in the presence of instantons. We then use these identities to compute the leading instanton contribution to the light-like cusp anomalous dimension and to anomalous dimension of twist-two operators with large spin

Madalena Lemos

The bootstrap approach to 4d superconformal field theories

We review the conformal bootstrap approach to 4d N>1 superconformal field theories (SCFTs), and how it constrains the space of allowed theories. From the landscape of N=2 SCFTs we focus on the "simplest" Argyres-Douglas theory and approach it both with numerical bootstrap techniques and with the Lorentzian inversion formula. We "zoom in" to the theory by specifying Coulomb branch data, and obtain constraints on its operator spectrum and OPE coefficients. We conclude with an outlook for the prospects of approaching other Argyres-Douglas theories.

Esperanza Lopez

"Far from equilibrium anomalous transport via holography"

In the presence of a gravitational contribution to the chiral anomaly, the chiral magnetic effect induces an energy current proportional to the square of the temperature in equilibrium. In holography the thermal state corresponds to a black hole. We numerically study holographic quenches in which a planar shell of scalar matter falls into a black hole and raises its temperature. During the process the momentum density (energy current) is conserved. The energy current has two components, a nondissipative one induced by the anomaly and a dissipative flow component. The dissipative component can be measured via the drag it asserts on an additional auxiliary color charge. Our results indicate strong suppression very far from equilibrium.

Gim Seng Ng

"Thermal Conformal Blocks"

We study conformal blocks for thermal one-point-functions on the sphere in conformal field theories of general dimension. These thermal conformal blocks satisfy second order Casimir differential equations and have integral representations related to AdS Witten diagrams. We give an analytic formula for the scalar conformal block in terms of generalized hypergeometric functions. As an application, we deduce an asymptotic formula for the three-point coefficients of primary operators in the limit where two of the operators are heavy.

Ida Zadeh

"AdS3/CFT2 holographic dualities with N = 3 and 1 supersymmetry"

We consider string theory on AdS3 x (S3 x S^3 x S^1) / Z2. This background supports N=3 or 1 supersymmetry depending on the action of the Z2 orbifold. We consider the construction which has N=(3,3) supersymmetry and propose an AdS3/CFT2 holographic duality which states that string theory on this background is dual to the symmetric product orbifold of S0 / Z2, where S0 is a 2d CFT with large N=(4,4) supersymmetry. We show that the BPS spectra and the modified elliptic genera of the CFT and the world-sheet string theory match, providing non-trivial support for our proposal. We also comment on the construction with N=1 supersymmetry.