Underlying Event and B-Hadron Decays in $t\overline{t}$ Events

TL;DR

This paper investigates the underlying event activity and b-quark fragmentation in top-antitop events at the CMS experiment, comparing data with simulations to improve top quark measurements.

Contribution

It provides the first detailed study of b-hadron decays and underlying event modeling in $t\overline{t}$ events using CMS data, aiding future precision top quark analyses.

Findings

Good agreement with MadGraph and Pythia 6 Tune Z2* simulations.

Exploration of alternative generator settings for underlying event characterization.

Results can help reduce systematic uncertainties in top quark mass measurements.

Abstract

We present exploratory studies of the underlying event activity and of fragmentation and hadronization of b quarks using $t\overline{t}$ candidate events in proton-proton collision data acquired by the CMS experiment. We reconstruct charm mesons in fully charged decay channels from the reconstructed tracks associated with the hadronization of b quarks from the top decay, and study their kinematics relative to the mother jet. A good agreement is found using MadGraph plus the Pythia 6 Tune Z2* simulation. The effects predicted by alternative settings and generators for the characterization of the underlying event are also explored. These results are expected to contribute in the future to more precise measurements in the top quark sector in particular of the top quark mass by either constraining systematic uncertainties related to the modeling of the underlying event in $t\overline{t}$ events or by paving the way for alternative mass measurement methods.