Probing the Structure of Jets with Event Shapes and Effective Field Theory

Event shapes are observables in e+e- annihilation pprobing the geometric structure of final states, revealing, for instance how close the event is to a two-jet final state. Angularities are a class of two-jet event shapes varying continuously in their sensitivity to the substructure of the final-state jets. Using the framework of Soft Collinear Effective Theory, we establish a factorization theorem for angularity distributions, resum the distributions in perturbation theory to next-to-leading logarithmic accuracy, and introduce a universal model for nonperturbative effects of soft radiation and hadroization. Finally, I discuss progress and prospects in generalizating to probing individual jets in e+e- or hadron collisions to distinguish their partonic origin.