Introduction to Soft-Collinear Effective Theory

TL;DR

This paper introduces Soft-Collinear Effective Theory (SCET), explaining its construction, key concepts, and applications in resummation techniques and infrared structure analysis in high-energy physics.

Contribution

It provides a comprehensive introduction to SCET, including derivations, examples, and applications in QCD processes and amplitude analysis.

Findings

Successful soft gluon and transverse-momentum resummation in Drell-Yan process

Derivation of infrared structure of gauge theory amplitudes using SCET

Illustration of SCET's application in high-energy QCD calculations

Abstract

These lectures provide an introduction to Soft-Collinear Effective Theory. After discussing the expansion of Feynman diagrams around the high-energy limit, the effective Lagrangian is constructed, first for a scalar theory, then for QCD. The underlying concepts are illustrated with the Sudakov form factor, i.e. the quark vector form factor at large momentum transfer. We then apply the formalism in two examples: We perform soft gluon resummation as well as transverse-momentum resummation for the Drell-Yan process using renormalization group evolution in SCET, and we derive the infrared structure of n-point gauge theory amplitudes by relating them to effective theory operators. We conclude with an overview of the different applications of the effective theory.