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Scale Separation and Effective Field Theory for Light Particles in High Energy Interactions

Scale separation is a common phenomena in which physics at large distances does not depend strongly on physics at shorter distances; making it possible, for example, for us to have learned a great deal about the dynamics of the solar system before the development of quantum mechanics. In high energy physics, scale separation is exemplified when short distance processes mediated by heavy particles or large momentum transfers can be factorized and decoupled from the long distance processes they contribute to. This phenomena can be used to separate perturbative, calculable physics from non-perturbative, incalculable physics, and it can also be used to improve the precision of theoretical predictions for the Standard Model when combined with resummation.

A powerful framework for taking advantage of scale separation in theoretical high energy physics is effective field theory. In this talk I discuss the application of effective field theory to factorization and resummation in high energy processes involving light QCD degrees of freedom (quarks and gluons) that typically produce jets or jet-like final states. Specifically, I discuss Soft Collinear Effective Theory (SCET) as the effective theory used to sum Sudakov logarithms, which limit theoretical precision in such processes. I report on a new formalism we have developed for SCET that we believe leads to a better theoretical understanding of the physics involved and streamlines the computation of subleading corrections to effective theory calculations.