Powheg+Vincia matching

[mseidel42]

PR description:

Add PowhegHooksVincia to veto Vincia emissions harder than the Powheg real radiation.

PR validation:

Comparison with event observables in ttbar:

[cmsbuild]

-code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-38471/30685

• This PR adds an extra 20KB to repository

• There are other open Pull requests which might conflict with changes you have proposed:

  • File GeneratorInterface/Pythia8Interface/plugins/Pythia8Hadronizer.cc modified in PR(s): Add to Pythia8Interface the plugin that uses HepMC3 #38452

Code check has found code style and quality issues which could be resolved by applying following patch(s)

• code-format:
  https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-38471/30685/code-format.patch
  e.g. curl -k https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-38471/30685/code-format.patch | patch -p1
  You can also run scram build code-format to apply code format directly

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-38471/30687

• This PR adds an extra 20KB to repository

• There are other open Pull requests which might conflict with changes you have proposed:

  • File GeneratorInterface/Pythia8Interface/plugins/Pythia8Hadronizer.cc modified in PR(s): Add to Pythia8Interface the plugin that uses HepMC3 #38452

[cmsbuild]

A new Pull Request was created by @mseidel42 (Markus Seidel) for master.

It involves the following packages:

• GeneratorInterface/Pythia8Interface (generators)

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

cms-bot commands are listed here

[SiewYan]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-069b15/25714/summary.html
COMMIT: 9f3c759
CMSSW: CMSSW_12_5_X_2022-06-22-2300/el8_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/38471/25714/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 2 differences found in the comparisons
• DQMHistoTests: Total files compared: 50
• DQMHistoTests: Total histograms compared: 3659307
• DQMHistoTests: Total failures: 8
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3659277
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 49 files compared)
• Checked 208 log files, 45 edm output root files, 50 DQM output files
• TriggerResults: no differences found

[SiewYan]

Hello @mseidel42 , thank you for the PR. Do I understand correctly that the Vincia emissions vetoing causes the 20% disagreement in the higher jet bins (green curve)? Which in turn to describe better on high pt region.

[mseidel42]

Hi Siewyan, the emission veto is necessary to run the Vincia shower with our standard Powheg LHE workflow.
Without veto, it would look more like the blue curve (=Powheg+Pythia without veto, which I produced by accident).

Some tuning might be necessary but it would be extremely useful to have Vincia available as an alternative parton shower. It is a more advanced shower based on 2->3 splittings instead of 1->2 DGLAP.

[SiewYan]

+1

Thanks @mseidel42 for the context!

[cmsbuild]

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

[perrotta]

+1