Resummed event shapes at hadron-hadron colliders

TL;DR

Resums a broad class of hadron-hadron dijet event-shape observables by defining global, exponentially forward-suppressed, and indirectly global variants amenable to CAESAR-based NL resummation. The paper establishes a cohesive framework for IRC-safe observables, detailing the LL and NLL structure through per-leg parameters and emission dynamics, and discusses experimental realities such as rapidity coverage and jet cuts. It presents concrete examples—transverse thrust, thrust minor, y23, jet masses, and broadenings—along with their forward-suppressed and recoil-based generalizations, highlighting how these observables probe perturbative radiation patterns, colour evolution, and non-perturbative effects like the underlying event. The work enables precise QCD studies at the Tevatron and LHC, providing a path toward fixed-order matching and offering diverse tools to study strong coupling, colour dynamics, and hadronisation in complex multi-jet final states.

Abstract

This article introduces definitions for a number of new event shapes and jet-rates in hadron-hadron dijet production. They are designed so as to be measurable in practice at the Tevatron and the LHC, and to be global so that they can be resummed with currently available techniques. We explain how to vary their sensitivity to beam fragmentation, limiting its impact for purely perturbative studies, or deliberately enhancing it so as to focus on non-perturbative effects. Explicit next-to-leading logarithmic resummed results are presented, as obtained with CAESAR.