Backport of new FxFx JetMatching plugin for Run3

[Cvico]

Backport of #39996, intended for Run3 MC production. I've checked with the GEN conveners and since I'm interested in 2022 production, I would need the plugin in CMSSW_12_4_X.

PR description:

This PR includes a plugin that allows to run an alternative Pythia8 FxFx jet matching prescription. The plugin has been implemented using the PluginFactory and the code has been directly taken from the new JetMaching.h file that can be found here. As stated in the link, this new jet matching algorithm only works in Pythia8.3 and beyond.

New versions of Madgraph5_aMC@NLO (v3.3.0 and beyond) introduce a new clustering procedure that distinguishes between jets that have been generated in a QCD or EWK vertex. This new jet matching prescription is required so the proper treatment of jets is also accounted for in the parton shower (PS) and matrix element matching step.

An example of its usage can be found in this fragment example. Basically, the user needs to apply two modifications to the common fragments used for FxFx merging:

1. Turn off Pythia8 default matching so new matchings can be add applied UserHooks. This can be done by adding the following line into the process parameters of the fragment:

    'JetMatching:doVeto = off',  # Turn OFF Pythia JetMatching

2. Include the new matching as a UserHook via the UserCustmization method.

    UserCustomization = cms.VPSet(
           cms.PSet(pluginName = cms.string("JetMatchingEWKFxFx"))
           ),

PR validation:

Tests using the local config file show that the JetMatchingEWKFxFx plugin properly matches between Pythia8.3 and MG33X gridpacks.
A set of preliminary results for ttW production can be found here.

[cmsbuild]

A new Pull Request was created by @Cvico (Carlos Vico Villalba) for CMSSW_12_4_X.

It involves the following packages:

• GeneratorInterface/Pythia8Interface (generators)

@SiewYan, @mkirsano, @Saptaparna, @cmsbuild, @alberto-sanchez, @menglu21, @GurpreetSinghChahal can you please review it and eventually sign? Thanks.
@alberto-sanchez, @mkirsano this is something you requested to watch as well.
@perrotta, @dpiparo, @rappoccio you are the release manager for this.

cms-bot commands are listed here

[menglu21]

@cmsbuild please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-20943a/30440/summary.html
COMMIT: e4139aa
CMSSW: CMSSW_12_4_X_2023-02-05-0000/el8_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/40702/30440/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 10 lines to the logs
• Reco comparison results: 6 differences found in the comparisons
• DQMHistoTests: Total files compared: 51
• DQMHistoTests: Total histograms compared: 3766083
• DQMHistoTests: Total failures: 8
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3766053
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 50 files compared)
• Checked 212 log files, 167 edm output root files, 51 DQM output files
• TriggerResults: no differences found

[menglu21]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_12_4_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_13_0_X is complete. This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[perrotta]

+1

• The test config added with this PR also works in 12_4_X