Dynamical approach to MPI four-jet production in Pythia

TL;DR

This paper enhances the modeling of Multiple Parton Interactions in Pythia by incorporating the extless 12 extgreater and extless 22 extgreater mechanisms using a model-independent approach, aligning well with experimental data and enabling predictions at higher energies.

Contribution

It introduces a unified, data-driven framework for MPI in Pythia, including the extless 12 extgreater and extless 22 extgreater mechanisms with improved theoretical consistency.

Findings

Good agreement with 7 TeV experimental data

Predictions for 14 TeV observables provided

Parameters linked to HERA data are model-independent

Abstract

We improve the treatment of Multiple Parton Interactions (MPI) in \textsc{Pythia} by including the \12 mechanism and treating the \22 mechanism in a model-independent way. The \22 mechanism is calculated within the mean field approximation, and its parameters are expressed through Generalized Parton Distributions extracted from HERA data. The parameters related to the transverse parton distribution inside the proton are thus independent of the performed fit. The \12 mechanism is included along the lines of the recently developed perturbative QCD formalism. A unified description of MPI at moderate and hard transverse momenta is obtained within a consistent framework, in good agreement with experimental data measured at 7 TeV. Predictions are shown for the considered observables at 14 TeV. The corresponding code implementing the new MPI approach is available.