[12_4_X backport] Do NaN-check before accepting a PF candidate for computing photon's isolation

[swagata87]

PR description:

This is a backport of #39120.
The need for backport to 12_4_X is explained in original PR's description and also here. To reiterate, photon's PF isolation is nan in some rare cases in Run3 data and MC. This PR fixes that. So it would be nice if 12_4_X MC production release has this fix in. This will also be useful for the rest of the prompt-reco data.

Related github issue: #39110

[cmsbuild]

A new Pull Request was created by @swagata87 (Swagata Mukherjee) for CMSSW_12_4_X.

It involves the following packages:

• RecoEgamma/PhotonIdentification (reconstruction)

@jpata, @cmsbuild, @mandrenguyen, @clacaputo can you please review it and eventually sign? Thanks.
@Sam-Harper, @jainshilpi, @valsdav, @lgray, @sobhatta, @afiqaize, @wrtabb, @varuns23, @ram1123 this is something you requested to watch as well.
@perrotta, @dpiparo, @qliphy, @rappoccio you are the release manager for this.

cms-bot commands are listed here

• Backported from Do NaN-check before accepting a PF candidate for computing photon's isolation #39120

[swagata87]

backport of #39120

[swagata87]

type egamma

[swagata87]

@cmsbuild please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-af6ee4/27100/summary.html
COMMIT: 93a4243
CMSSW: CMSSW_12_4_X_2022-08-25-1100/el8_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/39202/27100/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 50
• DQMHistoTests: Total histograms compared: 3677242
• DQMHistoTests: Total failures: 2
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3677218
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 49 files compared)
• Checked 208 log files, 45 edm output root files, 50 DQM output files
• TriggerResults: no differences found

[jpata]

+reconstruction

• bugfix/mitigation for reco::Candidate pt = -nan in some rare cases #39110
• physics changes expected insofar as rare NaN values become non-NaN in photon iso (not visible in the tests)
• backport of Do NaN-check before accepting a PF candidate for computing photon's isolation #39120

[jpata]

thank you @swagata87 for the quick action!

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_12_4_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_12_5_X is complete. This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @qliphy, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[swagata87]

thank you @swagata87 for the quick action!

no problem,
thank you for all the help and suggestions in the original PR to make the code more coherent and understandable.

[perrotta]

+1