Backport PythiaFiltertMultiAncestor fix to CMSSW_10_6 releases

[mhuwiler]

PR description:

Backport of #33491

In this PR we address a design problem of PythiaFilterMultiAncestor.cc, where charge conjugation is implicitly assumed by default for the particle under investigation
https://github.com/cms-sw/cmssw/blob/master/GeneratorInterface/GenFilters/plugins/PythiaFilterMultiAncestor.cc#L147
for its ancestor
https://github.com/cms-sw/cmssw/blob/master/GeneratorInterface/GenFilters/plugins/PythiaFilterMultiAncestor.cc#L122
, but it is not for its daughters.
https://github.com/cms-sw/cmssw/blob/master/GeneratorInterface/GenFilters/plugins/PythiaFilterMultiAncestor.cc#L190

The problem was noticed in some private tests and should not affect any samples produced so far using this filter (which in fact is just a limited number of samples for a specific analysis and they are not affected because in that case it was based on a Jpsi->mumu decay).
However, a backport to 10_6 (and 11?) would be good to avoid having production releases where the filter behaves in an unintended way.

PR validation:

The problem was noticed when using the filter to enforce D0->K-pi+ decay.

D0ToKpiFromDstFilter = cms.EDFilter(
"PythiaFilterMultiAncestor",
DaughterIDs = cms.untracked.vint32 ( -321, 211), # K-, pion+
DaughterMaxEtas = cms.untracked.vdouble( 1.e9, 1.e9),
DaughterMaxPts = cms.untracked.vdouble( 1.e9, 1.e9),
DaughterMinEtas = cms.untracked.vdouble(-1.e9, -1.e9),
DaughterMinPts = cms.untracked.vdouble(-1.0 , -1.0 ),
MaxEta = cms.untracked.double ( 99.0),
MinEta = cms.untracked.double (-99.0),
MinPt = cms.untracked.double (-1.0),
MotherIDs = cms.untracked.vint32 (413), # D*+
ParticleID = cms.untracked.int32 (421) # D0
)
Only one charge combination was present, but not the cc. The fix proposed here implements the correct behaviour.

[cmsbuild]

A new Pull Request was created by @mhuwiler for CMSSW_10_6_X.

It involves the following packages:

• GeneratorInterface/GenFilters (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

[qliphy]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-94872e/22663/summary.html
COMMIT: 4f99d58
CMSSW: CMSSW_10_6_X_2022-02-20-0000/slc7_amd64_gcc700
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/37065/22663/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

The workflows 140.53 have different files in step1_dasquery.log than the ones found in the baseline. You may want to check and retrigger the tests if necessary. You can check it in the "files" directory in the results of the comparisons

Summary:

• No significant changes to the logs found
• Reco comparison results: 4 differences found in the comparisons
• DQMHistoTests: Total files compared: 35
• DQMHistoTests: Total histograms compared: 3215686
• DQMHistoTests: Total failures: 2
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3215350
• DQMHistoTests: Total skipped: 334
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 34 files compared)
• Checked 143 log files, 29 edm output root files, 35 DQM output files
• TriggerResults: no differences found

[qliphy]

ping @cms-sw/generators-l2

[Saptaparna]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_10_6_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_12_3_X is complete. 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)

[qliphy]

+1