Talk Schedule

Talk Information

Changrim Ahn "Incomplete integrability in N=4 SYM theory"

In this talk, I will explain how the algebraic Bethe ansatz, main tool in quantum integrable system, can fail in solving integrable spin chains derived from the fishnet model, a simple cousin of the strongly twisted N=4 SYM theory. 

Jean-Emile Bourgine "An algebraic construction for real topological strings"

In 2011, Awata, Feigin and Shiraishi have introduced an algebraic construction for the topological strings vertex based on the representation theory of the quantum toroidal algebra of $mathfrak{gl}(1)$. This algebraic approach provides the technical tools needed to address several important questions (e.g. BPS/CFT correspondence, integrable aspects, dualities), and led to extend the topological vertex formalism to various geometric frameworks. In this talk, I will present a recent attempt at generalizing their construction to topological strings with orientifolds target space, also called "real topological strings". The relevant algebras are $mathbb{Z}_2$-orbifolds of the quantum $W_{1+infty}$ algebra, i.e. subalgebras obtained by projection over symmetric generators with respect to a reflection. Such orbifolds are also relevant in the definition of BCD type infinite algebras ($so(infty)$, $sp(infty)$) that appear, for instance, in the study of integrable hierarchies.

Hee-Joong Chung "Index for a Model of 3d-3d Correspondence for Plumbed 3-Manifolds"

In this talk, I will talk about the index for plumbed 3-manifolds. I first review the plumbed 3-manifolds and the homological block for them, which can be regarded as a half index of the corresponding 3d N=2 theory with a boundary condition via the 3d-3d correspondence. Then, I will review the case of Lens space as an example. By considering the structure of the homological block for plumbed 3-manifolds, I discuss a model for the corresponding 3d N=2 theory and calculate the index. I check the invariance of the index under the 3d Kirby moves and provide some remarks on the boundary condition.

Dongwook Ghim "On the Witten index of theories with 2 real supercharges"

In this talk, I will formulate Witten index problems for theories with two supercharges in a Majorana doublet, such as in d=3 N=1 or in d=1 N=2. Regardless of spacetime dimensions, theories of this kind show a rampaging wall-crossing behavior, in the parameter space of real superpotential. After brief discussion on the wall-crossing dynamics in scalar-multiplet-only theories, which is consistent with familiar Morse theoretic interpretation, I will extend the analysis to abelian gauge theories. Even though the index theorem for the latter is a little more involved, we reduce it to winding number counting of the neutral part of superpotential’s derivative dW. The holonomy saddle plays key roles for both dimensions and also in relating indices across dimensions.

Chiung Hwang "Dualities of quantum field theories in various dimensions"

In this talk, I introduce a new family of 4d N = 1 theories, called Eρσ[USp(2N)], which exhibit a novel type of 4d IR duality very reminiscent of the mirror duality enjoyed by the 3d N = 4 Tρσ[SU(N)] theories. I first reexamine the construction of 3d Tρσ[SU(N)] from T[SU(N)] using the duality web of the latter generated by the mirror duality as well as the so-called flip-flip duality. I then apply the same analysis to 4d E[USp(2N)], which leads to a new class of 4d theories enjoying the same duality web including the 4d reminiscent of the 3d mirror duality. I will also discuss the rich structure of dualities in lower dimensions derived from this 4d parent.

Saebyeok Jeong "Riemann-Hilbert correspondence and blown up surface defects"

I will talk about a quantum/classical duality between supersymmetric gauge theory and classical Hamiltonian dynamics describing isomonodromic deformations of a Fuchsian system. A big mystery has been that there are two seemingly different approaches from the quantum field theory side to this correspondence. I will explain how the surface defects on the blowup and novel blowup formula for their partition functions nicely reconcile the tension between the two approaches. I will also show that the intersecting surface defects produce the horizontal section of the associated Fuchsian system, allowing the computation of monodromy data in gauge theoretical terms.

Jung-Wook Kim "Classical physics of spinning black holes and compact stars from amplitudes"

One of the recent applications of modern amplitude techniques is the determination of classical dynamics of the two body problem with relativistic corrections, also known as post-Newtonian dynamics. I will explain how spin can be incorporated in this programme, putting an emphasis on the physical meaning of higher-order spin effects and their implementations. Two examples of classical physics that can be computed from amplitudes to all orders in spin will be presented; the 1PM spinning Hamiltonian and the matter stress tensor of Kerr-Newman black holes.

Se-Jin Kim "The Hamilton-Jacobi Equation of Holographic theory"

We study the Hamilton-Jacobi formulation of effective mechanical actions associated with holographic renormalization group flows when the field theory is put on the sphere and mass terms are turned on. Although the system is supersymmetric and it is described by a superpotential, Hamilton’s characteristic function is not readily given by the superpotential when the boundary of AdS is curved. We propose a method to construct the solution as a series expansion in scalar field degrees of freedom. The coefficients are functions of the warp factor to be determined by a differential equation one obtains when the ansatz is substituted into the Hamilton-Jacobi equation. We also show how the solution can be derived from the BPS equations without having to solve differential equations. The characteristic function readily provides information on holographic counterterms which cancel divergences of the on-shell action near the boundary of AdS.



Seok Kim "Thermodynamics of AdS black holes and their microstates"

Kanghoon Lee "Duality manifest approach for double copy"

I will present a generalization of the conventional Kerr-Schild(KS) formalism, a powerful tool for constructing exact solutions in general relativity, to double field theory and supergravities. I will describe the KS ansatz for the generalized metric in terms of a pair of null vectors and show that the equations motion reduce to linear equations under this ansatz. Based on this formalism, the exact double copy, which represents solutions of the Einstein equation in terms of solutions of the Maxwell equation, can be extended to the entire massless string NS-NS sector. Further, I’ll discuss the KS ansatz and the exact double copy for M-theory.

Kihong Lee "Large N gauge theories with dense spectrum"

I will talk about some 4d N=1 gauge theories that flow to IR SCFTs. Their IR SCFTs exhibit bands of spectrum of low-lying (single-trace) chiral operators at large N limit and their central charges scales linearly in N. I will explain the condition for the dense spectrum to appear. I will also show that they satisfy the weak gravity conjecture even though they have no weakly-coupled gravity duals.

Hisayoshi Muraki "Integrability of matrix models"

Matrix model is known to provide a description of two-dimensional topological gravity. The two-dimensional topological gravity on closed surfaces is equipped with an integrable hierarchy structure known as the KdV hierarchy. The Gaussian integral supplies a toy model as a simpler version of matrix model that inherits an integrable hierarchy structure as with two-dimensional topological gravity, yet it is the Burgers hierarchy rather than the KdV hierarchy. Making use of the Gaussian integral as a miniature, the talk would like to introduce you some notions of integrability in matrix models describing two-dimensional gravity.

Ioannis Papadimitriou "Update on supersymmetry anomalies"

I will consider supersymmetric QFTs with an anomalous R-symmetry or a flavor symmetry 't Hooft anomaly. In both these cases, the Wess-Zumino consistency conditions imply that there is an associated supersymmetry anomaly, with the same anomaly coefficient. For the flavor case, I will show how the associated supersymmetry anomaly arises via anomaly inflow from one dimension higher, and how N=1 superspace circumvents the supersymmetry anomaly through compensator fields. Moreover, I will show that the supersymmetry anomaly associated with an anomalous R-symmetry can be eliminated by a local counterterm that explicitly breaks R-symmetry. The resulting non anomalous supersymmetry can be identified with that obtained by coupling the theory to old minimal supergravity. I will conclude with some remarks on the implications for supersymmetric partition functions.

Jeong-Hyuck Park  "A single master equation for NS-NS sector and beyond"

What is the gravitational theory that string theory predicts? The conventional answer has been General Relativity.  However, the O(D,D) symmetry of string theory has shown to  augment this answer. I will introduce Double Field Theory as the O(D,D)  symmetry-based stringy completion of GR. In particular, a single master equation for the entire NS-NS sector as well as for various non-Riemannian geometries will be derived  as analogy to the Einstein equation in GR. [Ref. 1904.04705]

Myungbo Shim "Discrete Choices in 3d-3d Correspondence and Large N"

In this talk, we study twisted index formula in 3d-3d correspondence with respect to discrete choices of polarizations related to a 0-, 1-form global symmetry in 3d $mathcal{N}=2$ SCFT. Different discrete choices are realized by choosing a subgroup of the first $mathbb{Z}_{N}$ cohomology of the three-manifold in which SL(N) Chern-Simons theory is defined. We also present an example of this picture in the both of field theory and geometric computation. In the large N regime, we show that the leading order terms are intact but logarithmic corrections are affected by the choice of the discrete choices.  

Jaewon Song “Vanishing short multiplets in superconformal theories”