Improvement of muon post cleaning [MET tails] at 73X

[bachtis]

Hi,
This PR applies the following changes to the muon post cleaning:

1. Fixes an issue observed in CSA14 samples where a charged hadron is allowed to have a non high purity track that screws the MET. The story here is the following: When we import tracks we require high purity but if the track is the inner track of a muon we dont since the TuneP+PF can allow another refit to be used for the four vector. However the case was observed that the track was failing muID in PF and then a charged hadron was created > 500 GeV with no HCAL deposit ... Added a fix for those cases

2., In the attempt to improve the MET in PF there was a mistake in calculating it ending up with a MET=PFMET+offset . After studies switched to plain PFMET . Tried also track MET but doesnt help since
the post cleaning also creates neutral particles some times.

Example result plots follow in two samples:
1.Z prime -> this sample is great to see the effect of mismeasured muons since it has MET=0 and very high pt muons that can be mismeasured. In this sample the arithmetic RMS goes from 150->140 GeV

1. The Flat QCD sample shows smaller(as expected) improvement as well 30.07->30.03

red is before, black is after

Adding also the MUO POG: @trocino @battibass @abbiendi

[cmsbuild]

A new Pull Request was created by @bachtis for CMSSW_7_3_X.

Improvement of muon post cleaning [MET tails] at 73X

It involves the following packages:

RecoParticleFlow/PFProducer

@cmsbuild, @nclopezo, @StoyanStoynev, @slava77 can you please review it and eventually sign? Thanks.
@mmarionncern, @lgray this is something you requested to watch as well.
You can sign-off by replying to this message having '+1' in the first line of your reply.
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@nclopezo, @ktf you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[StoyanStoynev]

@cmsbuild please test

[cmsbuild]

+1
Tested at: f7e44b5
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5701/175/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5701/175/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5701/12/summary.html

[slava77]

In our reco tests I see that we generally just gain muon pf candidates (there's no migration from other particle types, at least in two tests that I checked manually).
The PR description is not very clear on it, I suppose I see case 1 here.
In all cases pf MET decreases.

In QCD flat-pt test (1K events):

• ev a: 22 GeV mu cand added; MET 38 down to 15 GeV
• ev b: 4.8 GeV mu cand added; MET shift from 5.7 to 1.0 GeV

From the code, what I observe is some longer-range effects.
Michalis, please comment and maybe update the PR description to describe the expected symptoms.

[bachtis]

Hi @slava77 .
The case 1 you will not see in a Relval. Those were 5 events in a full CSA14 dataset. What I saw when I rerecoed all Relval FlatQCD is that nothing changed in it when adding 1[of course when I rerecoed the bad events from CSA14 they were killed]. What you see come from 2 where the MET description was improved and the post cleaning is more aggresive on adding muons not ID by PF to fix the MET. Those changes you describe below are consistent with my plot above where I rereco all Flat QCD

[slava77]

+1

for #5701 f7e44b5
based on the review with notes above
tested in
CMSSW_7_3_X_2014-10-07-0200 (test area sign439, with #5754 added to both the reference and the new code)

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_3_X IBs unless changes (tests are also fine). @nclopezo, @ktf can you please take care of it?