IR-Improved DGLAP-CS QCD Parton Showers in Pythia8

TL;DR

This paper integrates IR-improved DGLAP-CS theory into Pythia8, enhancing the physical accuracy of soft process simulations at the LHC, and enabling better comparisons with detector data.

Contribution

The paper introduces IR-improved DGLAP-CS theory into Pythia8, expanding the tools available for LHC precision QCD simulations.

Findings

More physical soft limit in heavy gauge boson production processes

Enables direct comparison between IR-improved and unimproved showers in Pythia8

Facilitates improved detector simulation accuracy at LHC

Abstract

We introduce the recently developed IR-improved DGLAP-CS theory into the showers in Pythia8, as this Monte Carlo event generator is in wide use at LHC. We show that, just as it was true in the IR-improved shower Monte Carlo Herwiri, which realizes the IR-improved DGLAP-CS theory in the Herwig6.5 environment, the soft limit in processes such as single heavy gauge boson production is now more physical in the IR-improved DGLAP-CS theory version of Pythia8. This opens the way to one's getting a comparison between the actual detector simulations for some of the LHC experiments between IR-improved and unimproved showers as Pythia8 is used in detector simulations at LHC whereas Herwig6.5, the environment of the only other IR-improved DGLAP-CS QCD MC in the literature, Herwiri1.031, is not any longer so used. Our achieving the availability of the IR-improved DGLAP-CS Pythia8 then is an important step in the further development of the LHC precision theory program under development by the author and his collaborators.