Hadronization and Decay of Excited Heavy Hadrons in Herwig 7

TL;DR

This paper enhances the Herwig 7 event generator by improving the modeling of excited heavy hadron hadronization and decay processes, incorporating HQET-based polarization, decay modes, and updated production rates, validated against experimental data.

Contribution

The paper introduces new implementations in Herwig 7 for heavy hadron polarization, decay modes, and production rates, based on HQET symmetries and experimental data reanalysis.

Findings

Predictions align better with experimental data after updates.

Improved decay mode modeling enhances simulation accuracy.

Revised production rates reflect latest experimental insights.

Abstract

We revisit the hadronization and decay of excited heavy mesons and heavy baryons in Herwig 7 general-purpose event-generator, following four distinct steps: (i) Passing through the polarization of heavy hadrons at the end of parton shower through the application of heavy quark effective theory (HQET), where the emergence of a spin-flavour symmetry allows for the determination of the polarizations of the excited heavy mesons and heavy baryons from the helicity states of the light and heavy quarks. (ii) Improving the strong and radiative decay modes of the excited heavy mesons, where in the absence of conclusive experimental data on many of the decays, one needs to rely on HQET symmetries to determine the favoured decay modes, widths and branching ratios. (iii) Re-examination of the production rates of heavy hadrons using all available experimental data sources and (iv) performing a general tune for Herwig's free parameters to reflect the implemented changes. We compare our predictions against existing experimental data in the presence/absence of the newly implemented updates. These improvements will be available with Herwig-7.3.0 public release.