Joint Theory Seminar
Speaker: Gilly Elor (U. Oregon)
Title: Soft-Collinear Supersymmetry
Host: Xiaochuan Lu
Room: 432
Abstract: Soft-Collinear Effective Theory (SCET) is a framework for modeling the infrared structure of theories whose long distance behavior is dominated by soft and collinear divergences. I will demonstrate that SCET can be made compatible with supersymmetry (SUSY), explicitly with N = 1 SUSY Yang-Mills. For contrast arguments will be given that chiral SUSY theories with Yukawa couplings, specifically the single flavor Wess-Zumino model, are incompatible with the collinear expansion. SCET is formulated by expanding fields along a light-like direction and then subsequently integrating out degrees-of-freedom that are away from the light cone. Defining the theory with respect to a specific frame obscures Lorentz invariance - given that SUSY is a space-time symmetry, this presents a possible obstruction. The cleanest language with which to expose the congruence between SUSY and SCET requires exploring two novel formalisms which I will discuss: collinear fermions as two-component Weyl spinors, and SCET in light-cone gauge. By expressing SUSY Yang-Mills in "collinear superspace", a slice of superspace derived by integrating out half the fermionic coordinates, the light-cone gauge SUSY SCET theory can be written in terms of superfields. As a byproduct bootstrapping up to the full theory yields the first algorithmic approach for determining the SUSY Yang-Mills on-shell superspace action. This work paves the way towards discovering the effective theory for the collinear limit of N=4 SUSY Yang-Mills.
