Extracting a Short Distance Top Mass with Light Grooming

TL;DR

This paper introduces a precise method for measuring the top quark mass in proton-proton collisions using lightly groomed boosted top jets, balancing soft contamination removal with universal decay descriptions.

Contribution

It presents a novel factorization-based approach employing light soft drop grooming to accurately extract the top quark mass from jet mass distributions.

Findings

Universal hadronization corrections described by a single parameter.

Light grooming effectively reduces underlying event sensitivity.

Method applicable to both $pp$ and $e^+e^-$ collision data.

Abstract

We propose a kinematic method based on a factorization formula for precisely measuring the top quark mass $m_t$ in $pp$ collisions using boosted top jets with light soft drop grooming. By using light grooming, which is an order of magnitude less aggressive than typical grooming, we retain a universal description of the top mass scheme and decay effects, while still effectively removing soft contamination from the top jet. We give field theory results for the hadronization corrections for jets induced by a heavy top quark, showing they are described by a universal hadronic parameter that also appears for groomed light quark jets. An important phenomenological application of our results is that one can obtain $m_t$ in a short distance scheme by fitting the hadron level jet mass distributions, predicted by our factorization formula, to data or by Monte-Carlo calibration. The peaked distributions for $pp$ and $e^+e^-$ collisions are similar, up to sensitivity to underlying event which is significantly reduced by soft drop. Since soft drop implies that the $t$ and $\bar t$ jet masses each can be independently measured, the analysis enables the use of lepton+jet samples.