Changing handling of color indexes and anti particle creation for pythia8 EGun (9_3_X backport)

[pasmuss]

if this PR is a backport please specify the original PR and why you need to backport that PR

Backport for PR #29000 to CMSSW_9_3_17 for MC production (Fall17GS campaign). #29000 already approved and merged.

PR description (from original request):

Changes for proper treatment of color (conservation and codes):

• Increasing color index after generating one particle (anti particle obtains the same color, just on the anticolor column)
• Adding a check that if only colored particles are generated, the AddAntiParticle option is used to make sure that all colors are balanced
• Only affecting pythia8 EGun

PR validation (from original request):

Ran some tests locally with a core CMSSW script:

• not set AddAntiParticle at all (does not start, option must be set)
• set option to False (runs but does not generate anything and throws errors)
• set option to True (as expected: anti particle gets same anti color as particle gets color, index is not the same for two different particles)

[cmsbuild]

A new Pull Request was created by @pasmuss for CMSSW_9_3_X.

It involves the following packages:

GeneratorInterface/Pythia8Interface

@SiewYan, @efeyazgan, @mkirsano, @cmsbuild, @agrohsje, @alberto-sanchez, @qliphy can you please review it and eventually sign? Thanks.
@alberto-sanchez, @agrohsje, @mkirsano this is something you requested to watch as well.
@davidlange6, @silviodonato, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[qliphy]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/5079/console Started: 2020/03/09 17:10

[cmsbuild]

+1
Tested at: fb25bc0
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-91b1e2/5079/summary.html
CMSSW: CMSSW_9_3_X_2020-03-08-0000
SCRAM_ARCH: slc6_amd64_gcc630

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-91b1e2/5079/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 25
• DQMHistoTests: Total histograms compared: 2624448
• DQMHistoTests: Total failures: 204
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2624067
• DQMHistoTests: Total skipped: 177
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -24 KiB( 24 files compared)
• Checked 105 log files, 8 edm output root files, 25 DQM output files

[qliphy]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_9_3_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_11_1_X is complete. This pull request will now be reviewed by the release team before it's merged. @davidlange6, @silviodonato, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[silviodonato]

+1