Fixing ECAL-Trk energy combination such that it gets the uncorrected ecal energy err

[Sam-Harper]

Dear All,

A flaw in how the ECAL-Trk combination is done has been reported to E/gamma which introduces a discontinuity in the Et spectrum when scaled & smeared. This is due to using the corrected relative ecalEnergyErr for the ECAL-Trk combination. This bug fix now means that the uncorrected relative ecalEnergyErr is used.

In scale and smearing, the smearing is applied in quadrature to correct ecalEnergyErr which represents the per electron estimate of the resolution. However due to how the combination uses this value, this results in incorrect responses. Details can be seen in https://indico.cern.ch/event/716848/contributions/3042888/attachments/1669765/2678161/scaleSmearingAndEP.pdf and a follow up https://sharper.web.cern.ch/sharper/cms/talks/scaleAndSmearingReprise.pdf

This bug effects the values stored in the 2017 miniAODv2 and the 2016 legacy miniAODv2. Obviously it is too late for the 2017 miniAODv2 but if it could fix the legacy, that would be good. These fixes can be applied at the user level, which will have to be done for 2017 data.

When backporting to 94X, will I need a flag in the module config to reproduce the original bugged version?

[cmsbuild]

The code-checks are being triggered in jenkins.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-23677/5335

[cmsbuild]

A new Pull Request was created by @Sam-Harper (Sam Harper) for master.

It involves the following packages:

RecoEgamma/EgammaTools

@perrotta, @cmsbuild, @slava77 can you please review it and eventually sign? Thanks.
@jainshilpi, @varuns23, @lgray this is something you requested to watch as well.
@davidlange6, @slava77, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[davidlange6]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/28877/console Started: 2018/06/25 20:46

[cmsbuild]

+1
Tested at: 126de73
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-23677/28877/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-23677/28877/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 21 differences found in the comparisons
• DQMHistoTests: Total files compared: 31
• DQMHistoTests: Total histograms compared: 2899480
• DQMHistoTests: Total failures: 3
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2899287
• DQMHistoTests: Total skipped: 190
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 30 files compared)
• Checked 128 log files, 14 edm output root files, 31 DQM output files

[slava77]

When backporting to 94X (9_4_MAOD_X to be precise), will I need a flag in the module config to reproduce the original bugged version?

for the backport, please make it such that it is enabled only for the run2_miniAOD_80XLegacy.
This means that the old implementation should still be available in 94X via a configuration setting.

The alternative is to not do any changes in 94X but request an analysis release so that the fix can be applied on the fly. In this case, it will not be a part of the re-miniAOD.

[slava77]

+1

for #23677 126de73

• code changes are in line with the PR description. The specifics for a configurable backport discussed in Fixing ECAL-Trk energy combination such that it gets the uncorrected ecal energy err #23677 (comment) can stay in 94X
• jenkins tests pass and comparisons with the baseline show differences only in the miniAOD slimmedElectrons userFloat variables in the re-miniAOD workflows, as expected.

[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. @davidlange6, @slava77, @smuzaffar, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[fabiocos]

+1