27.09.2017 (Wednesday)

Segmented strings

Regular Seminar David Vegh (QMUL)

13:15 KCL
room Segmented strings

The goal of this talk is twofold. Firstly, I would like to popularize the segmented string approach for solving the classical string dynamics on certain symmetric spacetimes where the string motion is integrable. This allows for an exact discretization which renders the equation of motion discrete in both space and time. The corresponding string solution is a segmented string. I will review the properties of segmented strings and relate them to discrete-time Toda-type lattices. The second goal of the talk is to understand a concrete setup: a (segmented) string hanging from the boundary of three-dimensional AdS spacetime. According to the gauge/gravity duality, the string in the bulk is dual to a flux tube between a quark-antiquark pair in the boundary field theory. We assume that the string is initially (quasi-)static. Perturbing one of the endpoints creates a large propagating wave on the string. The non-linear time-evolution produces a number of interesting phenomena: energy cascades, pair-creation of cusps, and evaporating regions on the string. If time permits, I will also talk about the string worldsheet as a simple model for gravity, chaos, out-of-time-order four-point functions, and segmented membranes.