TICLv5 Adjust Linking step

[waredjeb]

PR description

This PR addresse the issue reported by the NGT group on Jet performance with TICLv5, showing a disruptive increase in the jet energy response. See presentation at HLT upgrade [1] from slide 15 with the comparison between TICLv4 and TICLv5.
This PR introduces a first stage of changes:

• Addressing the Trackster-Trackster linking, limiting links between objects in the HGCAL-CEE region, where the occupancy of the detector can lead the linking to merge too many tracksters, eventually building candidates with lot of contamination from PU that are affecting the final jet reconstruction.
• Moving the energy regression at the TICLCandidateProducer level, where the final calorimeter objects are produced after the additional Trackster-Trackster linking through the Track-Trackster linking.
• Remove Track-only candidates building for tracks that have not been linked to any trackster. This change remove possible candidate duplication in case of failure in the Track-Trackster linking step

Testing

The PR has been tested on CMSSW_15_1_0_pre5. Physics validation has been performed exploiting the HLT Jet Validation.
To evaluate the effectiveness of the changes, a comparison between Baseline and PR has been performed on a QCD sample in 200 PU, where the energy regression was turned off (as the regression is the other issue that will be fixed in a future PR).
Below some plots where on the left you have the Baseline while on the right the PR changes have been applied

pT Response with energy correction

Distributions after the changes look more healthy

Fake Rate

Major reduction in the jet fake rate in the [1.5,3.0] pseudorapidity region

HGCAL/TICL side

These changes leads to a mild drop in the overall efficiency. Tested on a pion sample in 200PU

These changes should be tested on workflow enabling the TICLv5 procModifier:

• 29634.203,29834.203, 29696.203,29896.203

@AuroraPerego @felicepantaleo

[1] https://indico.cern.ch/event/1578363/contributions/6650118/attachments/3119987/5532471/2025_08_19%20-%20Jet%20Validation%20HLT.pdf

[cmsbuild]

cms-bot internal usage

[cmsbuild]

-code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-48851/45991

ERROR: Unable to merge PR.

See log https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-48851/45991/cms-checkout-topic.log

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-48851/45992

• There are other open Pull requests which might conflict with changes you have proposed:
  • File RecoHGCal/TICL/plugins/TICLCandidateProducer.cc modified in PR(s): Add directories for TICL-EGM code development #48319
  • File RecoHGCal/TICL/plugins/TracksterLinkingbySkeletons.cc modified in PR(s): Add directories for TICL-EGM code development #48319

[cmsbuild]

A new Pull Request was created by @waredjeb for master.

It involves the following packages:

• HLTrigger/Configuration (hlt)
• RecoHGCal/TICL (reconstruction, upgrade)

@Martin-Grunewald, @Moanwar, @cmsbuild, @jfernan2, @mandrenguyen, @mmusich, @srimanob, @subirsarkar can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @SohamBhattacharya, @VourMa, @apsallid, @denizsun, @felicepantaleo, @forthommel, @hatakeyamak, @lecriste, @missirol, @mmusich, @rovere, @salimcerci, @sameasy, @sobhatta, @youyingli this is something you requested to watch as well.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

[mmusich]

test parameters:

• enable = hlt_p2_integration, hlt_p2_timing
• relvals_opt = --what upgrade
• workflows = ph2_hlt, 29634.203,29834.203, 29696.203,29896.203

[mmusich]

please test

[Moanwar]

So just to check, this is where you discarded the alone track, right?

[waredjeb]

Yes, here we just produce muons, but the other tracks are discarded, at least for now

[cmsbuild]

-1

Failed Tests: RelVals
Size: This PR adds an extra 68KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-c1e040/47984/summary.html
COMMIT: d41fcc2
CMSSW: CMSSW_15_1_X_2025-09-05-1100/el8_amd64_gcc12
Additional Tests: HLT_P2_INTEGRATION,HLT_P2_TIMING
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/48851/47984/install.sh to create a dev area with all the needed externals and cmssw changes.

RelVals

ValueError: Undefined workflows: 29696.203, 29896.203

• HLT P2 Timing: chart

[mmusich]

ValueError: Undefined workflows: 29696.203, 29896.203

under which matrix are these workflows? I can't find them under the upgrade one either.

[mmusich]

under which matrix are these workflows? I can't find them under the upgrade one either.

see https://github.com/cms-sw/cmssw/pull/48801/files#r2325506904.

[mmusich]

+hlt

• for waredjeb@7ea385e
• PR according to description and follow-up review

[jfernan2]

+1

[AdrianoDee]

+pdmv

[Moanwar]

+Upgrade

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @ftenchini, @sextonkennedy, @mandrenguyen (and backports should be raised in the release meeting by the corresponding L2)

[cmsbuild]

Milestone for this pull request has been moved to CMSSW_16_0_X. Please open a backport if it should also go in to CMSSW_15_1_X.

[mandrenguyen]

+1
waredjeb Note that this PR was merged in 16_0. If you need it in 15_1, a backport will be needed.