Extracting a short distance top mass with light grooming

Abstract

© 2019 authors. Published by the American Physical Society. We propose a kinematic method based on a factorization formula for precisely measuring the top quark mass mt 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 mt 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 an underlying event which is significantly reduced by the soft drop. Since the soft drop implies that the t and t̄ jet masses each can be independently measured, the analysis enables the use of lepton+jet samples.