Comparing particle multiplicity predictions: Insights from Pythia, Herwig with the LHCb use case

Abstract

Monte Carlo Event Generators are tools for simulating outcomes of high-energy collisions and particle production in High Energy Physics (HEP), such as those conducted at the Large Hadron Collider (LHC). Two of the most widely used general-purpose event generators are \textsc{Pythia} and \textsc{Herwig}, both of which play a significant role in understanding particle production, the internal structure of the proton, and the underlying physics of interactions that take place at LHC. This paper focuses on the modelling of low-energy diffractive and minimum-bias proton-proton collisions, where soft QCD effects and MPI dominate particle production, rather than hard perturbative processes. The LHCb experiment focuses on studying heavy quark hadrons, and given its specialization in precision measurements and rare decays, the choice of event generator for simulations is crucial. In this paper, we present a comparison between simulations using \textsc{Pythia} and \textsc{Herwig} with LHCb data. Our analysis demonstrates that \textsc{Pythia} provides a more consistent agreement with experimental measurements across key observables and hence remains the preferred generator for many particle physics analyses at the LHCb experiment, ensuring its continued importance in future high-energy physics research. \keywords{particle decays, rare decays, simulation, parameter sensitivity, generator tuning, simulation tools