Effective Field Theories for the LHC

TL;DR

This thesis applies effective field theories to analyze jet substructure at the LHC, introducing new observables and computational techniques to distinguish particles and study Higgs properties.

Contribution

It introduces the $D_2$ observable for jet discrimination and develops a helicity operator basis for simplified calculations in soft collinear effective theory.

Findings

Precision calculation of the $D_2$ observable for boosted boson identification.

Development of a helicity operator basis for effective field theory calculations.

Application of methods to study Higgs boson properties.

Abstract

In this thesis I study applications of effective field theories to understand aspects of QCD jets and their substructure at the Large Hadron Collider. In particular, I introduce an observable, $D_2$, which can be used for distinguishing boosted $W/Z/H$ bosons from the QCD background using information about the radiation pattern within the jet, and perform a precision calculation of this observable. To simplify calculations in the soft collinear effective theory, I also develop a helicity operator basis, which facilitates matching calculations to fixed order computations performed using spinor-helicity techniques, and demonstrate its utility by computing an observable relevant for studying the properties of the newly discovered Higgs boson.