CERN Accelerating science

The modelling of the formation of colour-singlet hadrons from coloured partons, known as Hadronization, is crucial for generating realistic events in Monte Carlo Event Generators. Due to limited understanding of the non-perturbative regime, physically motivated phenomenological hadronization models with tunable parameters are used and later tuned to the experimental data. Modern Monte Carlo generators primarily employ one of two hadronization models: the Lund string model, which is the default in $\text{Pythia}$, and the cluster model, which is the default in $\text{Herwig}$ and $\text{Sherpa}$. In this work, we combine the Lund string hadronization model, as implemented in $\text{Pythia 8}$, with $\text{Herwig 7}$ using $\text{TheP8I}$ interface. We tune the string model with $\text{Herwig 7}$'s Angular Ordered Parton Shower $(\text{AOPS})$ to lepton and hadron collision data, resulting in the Les Houches Tune $(\text{LH Tune})$, which shows good performance across a wide range of observables. The LH Tune will be included in the $\text{Herwig 7.4}$ release. This development enables a direct comparative study of the two hadronization models within$\text{}$Herwig, both interfaced with the Angular Ordered Parton Shower, which serves as the main motivation behind this work.