Prevent disabing of HGCal electron cluster preselection

[nsmith-]

Due to aliasing of enums EcalEndcap=HcalEndcap=2. I didn't add det_group == DetId::Ecal since I was worried the alias might have been permitted for pre-PhaseII detectors in case hitsAndFractions()[0] happens to be an HCal hit. Not sure if that actually happens or not...

Found when looking at hadron fraction of electrons in 930 Zee RelVals, where the cluster cut appears to not work

Here are the unique subdet IDs observed in the PF superclusters:

In [23]: ids=set()

In [26]: for e in events:
    ...:     cl = handles.recoSuperClusters_particleFlowSuperClusterHGCalFromMultiCl__RECO
    ...:     ids=ids.union( set([(c.seed().hitsAndFractions()[0].first.det(), c.seed().hitsAndFractions()[0].first.subdetId()) for c in cl]))
    ...:

In [27]: ids
Out[27]: {(4L, 2), (6L, 3), (6L, 4)}

i.e. DetId::Hcal, HcalEndcap, DetId::Forward, HGCEE, and DetId::Forward, HGCHEF.
I am not sure why HcalEndcap is used as a subdetId rather than HGCHEB, perhaps someone knows?

[cmsbuild]

A new Pull Request was created by @nsmith- (Nicholas Smith) for CMSSW_9_3_X.

It involves the following packages:

RecoEgamma/EgammaElectronProducers

@perrotta, @cmsbuild, @slava77 can you please review it and eventually sign? Thanks.
@jainshilpi, @Sam-Harper, @rovere, @lgray this is something you requested to watch as well.
@davidlange6, @slava77 you are the release manager for this.

cms-bot commands are listed here

• Backported from Prevent disabing of HGCal electron cluster preselection 94x #20591

[kpedro88]

@nsmith please make a corresponding PR to master (for 94X)

[kpedro88]

assign upgrade

[cmsbuild]

New categories assigned: upgrade

@kpedro88 you have been requested to review this Pull request/Issue and eventually sign? Thanks

[rovere]

@nsmith- HcalEndcap is used as a SubDet (of Hcal) not as a det, so it seems to be correct.
Could you please comment a bit further what the bug is, what your patch is doing and show some plots of the effect of the patch?

[nsmith-]

If the first hit in an HGC seed cluster happens to be from BH part of HGC, then its subdetId is 2, the same as EcalEndcap, so the if statement exits early and the cluster H/E cut is effectively disabled in this seed producer.
I checked with a cmsDriver that at least the patch does what it should, but waiting now on running the reco step again to see if there are any efficiency effects. Even if there are, it is kind of obvious we shouldn't be seeding GSF tracks with hadron clusters, no? Consider that if the first hit in the seed cluster hitsAndFractions() is not in BH, then the cut works as advertised.

[nsmith-]

@kpedro88, done, #20591

[rovere]

Ok, got it. It could make some clean-up, for sure, in high-PU events.

[kpedro88]

backport of #20591

[cmsbuild]

Pull request #20588 was updated. @perrotta, @cmsbuild, @kpedro88, @slava77 can you please check and sign again.

[perrotta]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/23137/console Started: 2017/09/21 09:22

[cmsbuild]

+1
Tested at: c059352
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-20588/23137/summary.html

The following merge commits were also included on top of IB + this PR after doing git cms-merge-topic:
971f5b1
You can see more details here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-20588/23137/git-log-recent-commits
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-20588/23137/git-merge-result

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-20588/23137/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 462 differences found in the comparisons
• DQMHistoTests: Total files compared: 26
• DQMHistoTests: Total histograms compared: 2645486
• DQMHistoTests: Total failures: 268
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2645029
• DQMHistoTests: Total skipped: 189
• DQMHistoTests: Total Missing objects: 0
• Checked 107 log files, 14 edm output root files, 26 DQM output files

[perrotta]

+1

• Identical to Prevent disabing of HGCal electron cluster preselection 94x #20591 in the master, repeating below the comments already posted there
• This is a bugifx, explained in detail in Prevent disabing of HGCal electron cluster preselection #20588 (comment) and Prevent disabing of HGCal electron cluster preselection #20588 (comment)
• It can clean up electron seeds, especially in high PU events
• Distributions in the phase2 workflows automatically run by jenkins are shown in Prevent disabing of HGCal electron cluster preselection 94x #20591 (comment) and discussed in Prevent disabing of HGCal electron cluster preselection 94x #20591 (comment) and following entries in the thread, and found in agreement with the expectations
• One should check if the efficiency is affected with some larger stat, but in any case the bug has to be fixed, and I don't see that check as a showstopper

[kpedro88]

+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_9_4_X is complete. This pull request will now be reviewed by the release team before it's merged. @davidlange6, @slava77, @smuzaffar (and backports should be raised in the release meeting by the corresponding L2)

[davidlange6]

merge