Triangle Seminars

Abstract:
Does our world respect causality at all energy scales? We explore constraints on low-energy dynamics which step from this assumption. Obstructions to a causal UV completion can be diagnosed using dispersive sum rules, which connect the infrared and ultraviolet. While dispersion relations originate in optics and quantum field theory, I will argue that their true purpose is gravity, where they become particularly powerful due to the maximal growth rate of this force with energy. This leads to the so-called graviton pole in sum rules. I will briefly review how, for non-gravitational low-energy effective theories, causality turns dimensional analysis estimates into sharp numerical bounds, and I will present initial results on gravitational effective theories.
[please email a.held@imperial.ac.uk for zoom link or password]

Abstract:
In this talk, I will discuss AdS super gluon scattering amplitudes in various spacetime dimensions. These amplitudes are dual to correlation functions in a variety of non-maximally supersymmetric CFTs, such as the 6d E-string theory, 5d Seiberg exceptional theories, etc. I will introduce a powerful method based on symmetries and consistency conditions, and show that it fixes all the infinitely many four-point amplitudes at tree level. I will also point out many interesting properties and structures of these amplitudes, which include the flat space limit, Parisi-Sourlas-like dimensional reduction, hidden conformal symmetry, and a color-kinematic duality in AdS. Along the way, I will also review some earlier progress and the relation with this work. I will conclude with a brief discussion of various open problems. [please email alejandro.cabo_bizet@kcl.ac.uk for the zoom link]

Abstract:
The study of possible constraints on RG flows is an important question in our understanding of quantum field theory. In this talk I will discuss a constraint which arises by considering the spectrum of BPS excitations (an H-theorem). Examples are found in the context of four-dimensional supersymmetric quantum field theories with enough supersymmetry that the BPS spectrum is explicitly computable. Among others, we will discuss applications in the context of Maruyoshi-Song flows. [for zoom link please contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

Abstract:
In this talk, I will discuss a family of three-point functions in ABJM theory, both at weak and strong coupling. This family of three-point functions involve two BPS sub-determinant operators called giant gravitons and one single trace operator, which can be BPS or non-BPS. In the first part of the talk, I will explain how to compute this type of three-point function at weak coupling using a large N effective field theory. The structure constant is given by the overlap of an integrable matrix product state and a Bethe state. In the second part, I will first clarify the prescription of computation at strong coupling. I will show that it is important to perform an average over the moduli space and also take into account the contributions from wave functions. The prescription is tested in N=4 SYM theory and then applied to ABJM theory.––––- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.