Add 15GeV cut to electron seeds for HI workflow (75X backport of #10504)

[harmonicoscillator]

(cherry picked from commit ffed6f2)

Backport of #10504 to 75X.

Again, this should not change any pp workflows, only HI.

[cmsbuild]

A new Pull Request was created by @richard-cms (R. Alex Barbieri) for CMSSW_7_5_X.

Add 15GeV cut to electron seeds for HI workflow (75X backport of #10504)

It involves the following packages:

RecoHI/Configuration

@cmsbuild, @cvuosalo, @slava77 can you please review it and eventually sign? Thanks.
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[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

+1
Tested at: 16a59d9
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-10505/6889/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-10505/6889/summary.html

[cvuosalo]

@richard-cms, @Slava:
This PR seems to eliminate electron GSF tracks in the HI workflow. Is that correct? I thought the 15 GeV cut would only remove fakes. See this plot, among others, in the Jenkins results for 140.53:

[harmonicoscillator]

This behavior is expected. The electronGsfTracks take the ecalDrivenElectronSeeds as a source (through process.electronCkfTrackCandidates), and so the large reduction in low-pT seeds will also show as a large reduction in electronGsfTracks as their sources disappear.

In a minimum bias sample we expect the number of real electrons above 15GeV to be miniscule.

@hiendoan , do you or @cmkuo have anything to add?

[mandrenguyen]

Workflows 140.4 or 302.0 are ZEE workflows that run the HI reco, which
should be useful for looking at high pT electrons.
Electrons below 15 GeV have never really been used in PbPb.

On 8/5/15 4:49 PM, R. Alex Barbieri wrote:

This behavior is expected. The electronGsfTracks take the
ecalDrivenElectronSeeds as a source (through
process.electronCkfTrackCandidates), and so the large reduction in
low-pT seeds will also show as a large reduction in electronGsfTracks
as their sources disappear.

In a minimum bias sample we expect the number of real electrons above
15GeV to be miniscule.

@hiendoan https://github.com/hiendoan , do you or @cmkuo
https://github.com/cmkuo have anything to add?

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Reply to this email directly or view it on GitHub
#10505 (comment).

---

Matthew Nguyen
Chargé de Recherche
LLR-Ecole Polytechnique
91128 Palaiseau FRANCE

+33 1 69 33 55 65

[harmonicoscillator]

I ran the 140.4 workflow that @mandrenguyen suggested for 20 events and compared before/after this PR the recoGsfTracks:

original:
https://twiki.cern.ch/twiki/pub/CMS/PhotonAnalyses2015/recoGsfTracks_electronGsfTracks__RECO.obj.pt_originalf.gif

After cut:
https://twiki.cern.ch/twiki/pub/CMS/PhotonAnalyses2015/recoGsfTracks_electronGsfTracks__RECO.obj.ptf.gif

You can see that only the low-pT tracks are removed, as we expect (and want!).

[cvuosalo]

+1

For #10505 16a59d9

Adding 15 GeV cut to electron seeds for HI to reduce fake rate for jets. There should be no change for pp workflows. The 76X version of this PR, #10504, includes validation plots from the developers.

The code changes are satisfactory, and Jenkins tests against baseline CMSSW_7_5_X_2015-07-31-1100 show no significant differences for pp workflows. For the HI workflow 140.53, electron GSF tracks disappear, which, as discussed above, is the desired and intended effect. Otherwise there are very small differences as expected from the reduction in fake electrons and jets.
An extended test of 100 events for workflow 140.53 against baseline CMSSW_7_5_X_2015-07-31-1100 also shows the expected loss of low-pT electrons and also very small differences expected from the reduction in fake electrons and jets. Plots of the electron loss are below.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs once checked with relvals in the development release cycle of CMSSW (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1