Navigating the Maze of Regge Physics with EFT

by Anjie Gao (MIT)

Friday 21 Mar 2025, 11:00 → 13:00 US/Eastern

CFNS Library (https://bnl.zoomgov.com/j/1614715193?pwd=WkwxODVWdzZzb29zQnZRVGp3VTBDQT09)

The high energy (Regge) limit provides a playground for understanding all order loop structures of scattering amplitudes, and plays an important role in the description of many phenomenologically relevant applications, including small-x physics, diffraction, saturation, etc. For the simplest 2->2 Regge amplitude, while well understood in the planar limit, the structure of non-planar corrections introduces many fascinating complexities, for which a general all-order organizing principle is still lacking. In this talk, I discuss the structure of multi-Reggeon exchanges in the context of the effective field theory for forward scattering (Glauber SCET, a top-down EFT derived from QCD), and their factorization into collinear functions and soft functions. I show that the Regge limit can be understood through the rapidity RG evolution of these functions, from which we can define Regge-like anomalous dimensions in a gauge invariant manner. A new feature of the EFT is the ability to calculate these anomalous dimensions from either the soft or collinear sectors. I discuss the solutions of these RG evolutions for different color channels, including 8a (gluon Reggeization), 8s, 1s (pomeron), 27,  1a (odderon), 10 (decupletons), 35 (triantapentons) and 64 (tetrahexaconton). Indeed, this EFT organization provides a natural all-order definition of the gluon Regge trajectory for the first time. Along the way, we will see the emergence of a 2-dimensional Regge theory on the transverse plane.