Theoretical Physics Colloquium
Many-body emergent dynamics of QCD in the Regge limit
by Prof. Raju Venugopalan (Brookhaven National Lab.)
Tuesday, March 5, 2019 from to (Asia/Kolkata)
The quest to understand the Regge limit in QCD was a strong impetus for the early development of string theory, which moved away in different directions after the discovery of asymptotic freedom. The latter however has powerful implications for the Regge limit since it leads to an explosive proliferation of gluons that is only slowed by their recombinant many-body interactions, a process analogous to the reaction-diffusion dynamics of traveling wave fronts in statistical mechanics. In the first part of of this talk, we shall outline how the physics of saturated glue is captured by a classical effective field theory, the Color Glass Condensate (CGC), wherein an emergent semi-hard scale allows for weak coupling analyses of nonperturbative dynamics in hadron wavefunctions, Remarkably, a a color memory effect in the CGC bears an exact analogy to the gravitational memory effect that could be discovered by LIGO in the near future. This correspondence in turn prompts one to speculate that asymptotic BMS-like symmetries analogous to those in gravity may also apply in QCD's Regge limit, leading to novel insight into how pions form "soft hair" on glue. In the second part of the talk, we discuss how the CGC provides an ab initio picture of thermalization and hydrodynamics in ultrarelativistic heavy-ion collisions. We outline how fast scrambling causes the system to flow to a nonequilibrium turbulent attractor, sketch its topological properties, and note a remarkable universality between this attractor and cold atomic gases prepared with the same boundary conditions.