Fix for high energy behaviour of ecal pfcluster corrections

[bendavid]

limit maximum energy (pt) for ecal pf cluster corrections to avoid bad extrapolation beyond region of correction derivation. At 1TeV this was introducing a ~1% scale shift in the barrel and a ~10% scale shift in the endcap.

Likely issue is limited kinematic coverage of training sample combined with tails in the energy response distribution sufficiently large to create well-populated BDT bins in the region about the kinematic limit of the sample, where all photons are by construction overmeasured (and therefore overcorrected downwards in energy)

@bachtis @lgray @matteosan1

@konush can you incorporate this change into your evaluation scripts and run the validation plots again to make sure this doesn't introduce any strange behaviour in scale/resolution vs eta/pt? (at least up to the kinematic limit in the present samples...)

[cmsbuild]

A new Pull Request was created by @bendavid (Josh Bendavid) for CMSSW_7_5_X.

Fix for high energy behaviour of ecal pfcluster corrections

It involves the following packages:

RecoParticleFlow/PFClusterProducer

@cmsbuild, @cvuosalo, @nclopezo, @slava77 can you please review it and eventually sign? Thanks.
@mmarionncern, @bachtis, @lgray this is something you requested to watch as well.
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[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

+1
Tested at: 33e06c4
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8949/7401/summary.html

[bendavid]

Jet scale changes looks reasonable/as expected.

R9 changes make no sense. I strongly suspect that these plots have inconsistent numerator and denominator. (Change could be explained if plots were made using raw e3x3 for the numerator and corrected energy for the denominator. If this is the case DQM plots should be fixed.)

[slava77]

about r9: this reminds me now that this is not the first time the R9 plots change and we discuss this.

@deguio
@argiro @emanueledimarco could you please check

[slava77]

+1

for #8949 33e06c4

tested in CMSSW_7_5_X_2015-05-04-1100 /test area sign544/

• the change in the code is effectively a transformation of input variable for the correction MVA/BTD, which should eventually be made during training. The setup is somewhat fragile though: there is a non-zero chance that the next training will have the high-E response more adequately and will need a code change cycle (this would be a higher order effect though).
• comparisons with baseline show expected behavior

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs unless changes (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @smuzaffar

[emanueledimarco]

@slava77 I am a bit surprised by the change in R9: why the PF cluster energy enters here? It should be E1/E(3x3)

[slava77]

it's probably one of the incomplete fixes:
the last time during review of #7558 a plot in pileup dependence was mentioned and it was fixed in #7595
I guess back then I assumed that the issue is relate to R9 and never posted a plot from other monitors.

The same problem is in the plots posted here as well
http://cmslxr.fnal.gov/lxr/source/DQM/EcalMonitorTasks/src/ClusterTask.cc?v=CMSSW_7_5_0_pre3#0432

[davidlange6]

+1