[PWGHF] Fix Xic0 reconstruction online bug, add KF selection, new Xic0 task, and candidateCreator cleanup

[Rrantu]

In this PR, I fix an online application bug, add KF variable selection in candidateSelector, introduce a new Xic0 task file (taskXic0ToXiPiKf.cxx), and remove an unused variable and fix an existing bug in the KFParticle part ofcandidateCreator — including an incorrect ctau calculation, incorrect variable names and PDG codes in the cosThetaStar calculation, and a missing testBit check at the beginning.

[github-actions]

O2 linter results: ❌ 1 errors, ⚠️ 0 warnings, 🔕 2 disabled

[alibuild]

Error while checking build/O2Physics/o2 for f0e17df at 2025-07-07 19:38:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/11860-slc9_x86-64/0/PWGHF/TableProducer/candidateCreatorXic0Omegac0.cxx:1465:28: error: unused variable 'coordVtxCharmBaryon' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/11860-slc9_x86-64/0/PWGHF/TableProducer/candidateCreatorXic0Omegac0.cxx:1465:28: error: unused variable 'coordVtxCharmBaryon' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/11860-slc9_x86-64/0/PWGHF/TableProducer/candidateCreatorXic0Omegac0.cxx:1465:28: error: unused variable 'coordVtxCharmBaryon' [-Werror=unused-variable]
ninja: build stopped: subcommand failed.
## sw/BUILD/ef0bfa363f0e36dbca43eafa7b9a4f237383317f-latest/log
/sw/SOURCES/O2Physics/11860-slc9_x86-64/0/PWGHF/TableProducer/candidateCreatorXic0Omegac0.cxx:1465:28: error: unused variable 'coordVtxCharmBaryon' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/11860-slc9_x86-64/0/PWGHF/TableProducer/candidateCreatorXic0Omegac0.cxx:1465:28: error: unused variable 'coordVtxCharmBaryon' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/11860-slc9_x86-64/0/PWGHF/TableProducer/candidateCreatorXic0Omegac0.cxx:1465:28: error: unused variable 'coordVtxCharmBaryon' [-Werror=unused-variable]
ninja: build stopped: subcommand failed.

Full log here.

[Rrantu]

Hi @fgrosa, I’ve updated the code. Could you please take a look and approve it?

[vkucera]

Please extend the PR description with an explanation of the bug that you fixed.

[Rrantu]

Please extend the PR description with an explanation of the bug that you fixed.

Thanks for the reminder! I’ve now extended the PR description with details about the bug I fixed earlier.

[fgrosa]

Hi @Rrantu please also fix the usage of tracks (propagated to the PV) and tracksIU (propagated at the innermost update) for charm baryon bachelor and Xi/Omega daughters instead (as discussed in #11764)

Please also wait that #11764 is merged before merging this one (I would expect quite some conflicts)

Thanks!

Hi @Rrantu please still fix the usage of the proper tracks (i.e. not propagated to the PV for the cascade daughters, and propagated to the PV for the bachelor) in the runKfXic0CreatorWithKFParticle function. I missed that in #11764 it was only partially done by @FDUEnrich, changing from the consumed table from Tracks to TracksIU, but Tracks should still be used for the charm bachelor. It would also be great if you could fix it also in the other functions that uses the KFParticle, i.e. runKfOmegac0CreatorWithKFParticle, runOmegac0Xic0ToOmegaKaCreatorWithKFParticle (since this is really a bug to be fixed). Thanks!

[Rrantu]

Hi @Rrantu please also fix the usage of tracks (propagated to the PV) and tracksIU (propagated at the innermost update) for charm baryon bachelor and Xi/Omega daughters instead (as discussed in #11764)
Please also wait that #11764 is merged before merging this one (I would expect quite some conflicts)
Thanks!

Hi @Rrantu please still fix the usage of the proper tracks (i.e. not propagated to the PV for the cascade daughters, and propagated to the PV for the bachelor) in the runKfXic0CreatorWithKFParticle function. I missed that in #11764 it was only partially done by @FDUEnrich, changing from the consumed table from Tracks to TracksIU, but Tracks should still be used for the charm bachelor. It would also be great if you could fix it also in the other functions that uses the KFParticle, i.e. runKfOmegac0CreatorWithKFParticle, runOmegac0Xic0ToOmegaKaCreatorWithKFParticle (since this is really a bug to be fixed). Thanks!

Hi @fgrosa, I’ve fixed the usage of the proper tracks — cascade daughters now use TracksIU, and the charm bachelor uses Tracks, as expected. Let me know if anything still looks off.

[fgrosa]

Casting with _as<> will raise a runtime error, since the Tracks and TracksIU tables have the same index. You need to access the track tables "by hand" with rawIteratorAt, as done in the process functions for the DCAFitter, see e.g.

O2Physics/PWGHF/TableProducer/candidateCreatorXic0Omegac0.cxx

Lines 476 to 478 in 2d0c61b

	auto trackCascDauCharged = lfTracks.rawIteratorAt(trackCascDauChargedId); // pion <- xi track
	auto trackV0Dau0 = lfTracks.rawIteratorAt(trackV0Dau0Id); // V0 positive daughter track
	auto trackV0Dau1 = lfTracks.rawIteratorAt(trackV0Dau1Id); // V0 negative daughter track

[Rrantu]

Thank you! I’ve updated the code to use rawIteratorAt() instead of _as<>.