Topological production of charmonia with event-shape engineering in $pp$ collisions at $\sqrt{s} = 13$ TeV using PYTHIA8

TL;DR

This paper investigates how event shape observables, specifically transverse spherocity, influence prompt and nonprompt J/ψ production in 13 TeV proton-proton collisions using PYTHIA8, highlighting potential for experimental event selection based on underlying QCD processes.

Contribution

It introduces the use of transverse spherocity as an event shape variable to study heavy quarkonium production and its correlation with underlying event activity in PYTHIA8 simulations.

Findings

Transverse spherocity correlates with the number of multiple parton interactions.

Event shape selection affects J/ψ production rates.

Results suggest potential for experimental event classification based on topology.

Abstract

The production of heavy quarks (charm and beauty) in high-energy hadronic and nuclear collisions provides an excellent testing ground for the theory of strong interactions and validates models based on quantum chromodynamics (QCD). In this work, prompt and nonprompt production of $\rm{J/}\psi$ in $pp$ collisions at $\sqrt{s}=13$ TeV are studied as a function of transverse spherocity using PYTHIA8. $\rm{J/}\psi$ is reconstructed via its electromagnetic decay to dielectrons and dimuons, in mid- and forward-rapidity, respectively. Transverse spherocity, an event shape observable, is used to distinguish hard QCD events from the softer, isotropic ones. In PYTHIA8, the production of $\rm{J/}\psi$ can be influenced by the average number of multiple parton interactions ($\langle N_{\rm mpi} \rangle$), owing to the underlying events (UE), which have a dominant contribution to particle production at lower transverse momentum. Since transverse spherocity is correlated to $\langle N_{\rm mpi} \rangle$, this can serve as an experimentally accessible tool for event selection to study the underlying QCD processes influencing the prompt and nonprompt $\rm{J/}\psi$ production. This study reveals the correlation between heavy-flavor production dynamics and topological event selection in $pp$ collisions using PYTHIA8, whose relevance awaits experimental validation.