adding Py8 Pt Gun with exponentially falling pT distribution

[bennettgberg]

PR description:

This PR adds a Pythia8 Pt Gun that uses an exponentially falling pT distribution between the minimum and maximum pT values instead of the uniform pT distribution.
This is needed for Central MC production of EtaTo2MuGamma, which is a background needed for the eta->2mu2e analysis. But the gun could also be used more generally with arbitrary minimum and maximum pT values.
The exponentially falling distribution is needed because the production cross section of the eta meson falls off rapidly with increasing pT, so much more statistics is needed at lower pT values (but only above the acceptance threshold).

It is just adding a new Pt gun, so output of existing code will not change.
JIRA ticket where this PR is requested: https://its.cern.ch/jira/browse/CMSBPHMC-52

PR validation:

code-checks, code-format, and runTheMatrix.py were all run successfully.
The new plugin was also tested thoroughly and successfully used to produce EtaTo2Mu2Gamma events in CMSSW_12_4_17 and CMSSW_13_0_14.

If this PR is accepted I will open a backport for CMSSW_12_4_X for Summer22 production.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-43354/37819

• This PR adds an extra 32KB to repository

[cmsbuild]

A new Pull Request was created by @bennettgberg for master.

It involves the following packages:

• Configuration/Generator (generators)
• GeneratorInterface/Pythia8Interface (generators)

@alberto-sanchez, @SiewYan, @menglu21, @GurpreetSinghChahal, @mkirsano, @cmsbuild, @bbilin can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @alberto-sanchez, @fabiocos, @mkirsano, @missirol this is something you requested to watch as well.
@sextonkennedy, @rappoccio, @antoniovilela you are the release manager for this.

cms-bot commands are listed here

[Kiarendil]

Dear @menglu21 , @bbilin ,
can you please start tests for this PR?
Thank you in advance :)

[afrankenthal]

Hi all, we will greatly appreciate it if this can be taken care of in a timely manner. We of course understand that everyone is busy with many ongoing projects and deadlines, but we believe (and hope) that this PR will not require a significant effort from any of the involved parties because it's a straightforward modification of an existing particle gun. Since we will need to produce a relatively large number of events, which will carry its own delay, we are hoping that at least the approval for this simple PR can proceed smoothly. Right now we see that the "unfinished checks" need some "authorized user" to issue the test command, so it sounds like it should be a quick thing to do.

Thank you for your help,
Andre on behalf of the authors

[bbilin]

@cmsbuild please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-342989/36140/summary.html
COMMIT: ff19e72
CMSSW: CMSSW_14_0_X_2023-11-28-1100/el8_amd64_gcc12
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/43354/36140/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 362 lines to the logs
• Reco comparison results: 10 differences found in the comparisons
• DQMHistoTests: Total files compared: 50
• DQMHistoTests: Total histograms compared: 3367918
• DQMHistoTests: Total failures: 7
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3367889
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 49 files compared)
• Checked 214 log files, 167 edm output root files, 50 DQM output files
• TriggerResults: no differences found

[bbilin]

+1

[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. @sextonkennedy, @rappoccio, @antoniovilela (and backports should be raised in the release meeting by the corresponding L2)

[Kiarendil]

Dear @sextonkennedy, @rappoccio, @antoniovilela ,
can you please merge it to master?

GEN asks us to check this plugin on an IB release before we move on with the back-ports.

Thanks,
Kirill for the BPH

[rappoccio]

+1