Systematic Improvement of Parton Showers with Effective Theory

Note: 12:30 PM
Speaker: Matt Baumgart, Johns Hopkins University

When: October 25, 2010 (Mon), 12:30PM to 01:30PM (add to my calendar)
Location: PRB 595

This event is part of the HET Seminar Series.

Abstract:
We carry out a systematic classification and computation of next-to-leading order kinematic power corrections to the fully differential cross section in the parton shower. To do this we devise a map between ingredients in a parton shower and operators in a traditional effective field theory framework using a chain of soft-collinear effective theories. Our approach overcomes several difficulties including avoiding double counting and distinguishing approximations that are coordinate choices from true power corrections. Branching corrections can be classified as hard-scattering, that occur near the top of the shower, and jet-structure, that can occur at any point inside it. Hard-scattering corrections include matrix elements with additional hard partons, as well as power suppressed contributions to the branching for the leading jet. Jet-structure corrections require simultaneous consideration of potential $1\to 2$ and $1\to 3$ branchings. The interference structure induced by collinear terms with subleading powers remains localized in the shower.