Improving the Understanding of Jet Grooming in Perturbation Theory

TL;DR

This paper advances the theoretical understanding of jet grooming in perturbation theory by calculating cross sections, analyzing higher-order effects, and assessing factorization assumptions, thereby improving precision in jet physics analyses.

Contribution

It provides the first analytic leading-order cross section for groomed heavy jet mass and examines higher-order effects and factorization assumptions in perturbative calculations.

Findings

Cusps are softened at higher orders in perturbation theory.

Terms violating factorization assumptions are numerically small.

Results inform the convergence and uncertainties in groomed jet observable calculations.

Abstract

Jet grooming has emerged as a necessary and powerful tool in a precision jet physics program. In this paper, we present three results on jet grooming in perturbation theory, focusing on heavy jet mass in $e^+e^-\to$ hadrons collisions, groomed with the modified mass drop tagger. First, we calculate the analytic cross section at leading-order. Second, using the leading-order result and numerical results through next-to-next-to-leading order, we show that cusps in the distribution on the interior of phase space at leading-order are softened at higher orders. Finally, using analytic and numerical results, we show that terms that violate the assumptions of the factorization theorem for groomed jet mass are numerically much smaller than expected from power counting. These results provide important information regarding the convergence of perturbation theory for groomed jet observables and reliable estimates for residual uncertainties in a precision calculation.