[8.1.X] Prevent negative jet smearing factor

[blinkseb]

If the smearing factor is negative, the energy becomes negative, and the
jet direction is inverted. Avoid this problem by setting a minimum valid
energy for the jet. If, after smearing, the jet energy is smaller than
this limit, the smearing factor is recomputed.

Tested and working as expected. Fixes a bug reported on the HN.

[cmsbuild]

A new Pull Request was created by @blinkseb (Sébastien Brochet) for CMSSW_8_1_X.

It involves the following packages:

PhysicsTools/PatUtils

@cmsbuild, @cvuosalo, @slava77, @davidlange6 can you please review it and eventually sign? Thanks.
@TaiSakuma, @imarches, @ahinzmann, @acaudron, @mmarionncern, @rappoccio, @jdolen, @nhanvtran, @schoef, @ferencek, @gpetruc, @mariadalfonso, @pvmulder this is something you requested to watch as well.
@slava77, @smuzaffar you are the release manager for this.

cms-bot commands are list here #13028

[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/14197/console

[cmsbuild]

+1
Tested at: b60c120
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-15249/14197/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-15249/14197/summary.html

[slava77]

+1

for #15249 b60c120

• changes are in line with the description
• jenkins tests pass and comparisons show no differences (the affected module runs in PAT/miniAOD and contributes to MET uncertainties, which are not monitored [or, maybe the thresholds for that are above the expected phase space of the fixed issue])
  • looking at the copy of jenkins tests outputs in 136.731, there are no changes in the size of MET or jet branches in miniAOD