Bugfix: Fake muon tracks become charged hadrons in PF (81X version of #14669)

[bachtis]

This fixes tail events that appeared in 80X. Those fake tracks we have seen before but they were appearing in less pure iterations for which we applied Dpt/pt cuts

Actions taken:
+Add a very loose Dpt/pt cut <20 in other iterations
+Cut tracks that are not belonging to muons but are not high purity

THis should only affect events in tails

[cmsbuild]

A new Pull Request was created by @bachtis (Michalis Bachtis) for CMSSW_8_1_X.

It involves the following packages:

RecoParticleFlow/PFProducer

@cmsbuild, @cvuosalo, @slava77, @davidlange6 can you please review it and eventually sign? Thanks.
@mmarionncern, @lgray, @rafaellopesdesa, @cbernet this is something you requested to watch as well.
@slava77, @Degano, @smuzaffar you are the release manager for this.

cms-bot commands are list here #13028

[slava77]

@bachtis please copy full description to this PR from 80X (edit the top section right below the title).
80X version is DOA by policy

[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/13241/console

[cmsbuild]

+1
Tested at: 6c7a639
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-14670/13241/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-14670/13241/summary.html

[bachtis]

Hello?

[slava77]

it's not forgotten

[slava77]

Some related plots:
wf 1313 (3TeV dijet)
substantial decrease in pf ch around 1 TeV is balanced out by increase in pf nh (and also a bit in photons and muons)

ch MET tail is down substantially

full pf MET is marginally affected

the chH fraction is down, as expected

yield of pfTaus at high pt end decreased by ~x2
[the ET is not fake here, unclear if it's all good; OTOH, it's unclear if the EI tau selection is still all that meaningful]

This looks like an effect for fakes.
I checked with Zptautau at M=4TeV
there is no significant effect:

Looking at jet components, the main migration is (chFrac1, photonFrac0) to some more sensible values (there are apparently sprays of pseudo-good tracks that were previously used up to turn all calo energy to charged hadrons)

[slava77]

+1

for #14670 6c7a639

• code change is as described
• jenkins tests pass and comparisons with baseline show small differences starting from PF
• local tests with higher PT samples that are expected to be more affected show reasonable behavior (see plots posted above/earlier)

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_8_1_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1