[PWGDQ] dqEfficiency_withAssoc/VarManager: Add MC-truth secondary vertex for B→J/ψK triplet quantities by torkjellsdatter · Pull Request #13890 · AliceO2Group/O2Physics

torkjellsdatter · 2025-11-19T14:26:51Z

Purpose

Implement MC-truth / generated secondary vertex quantities for the triplet observables used in the B → J/ψ K analysis.

Changes

PWGDQ/Core/VarManager.h

New function VarManager::FillTrackCollisionMC.
Takes a daughter track, the mother track, and the generated collision as arguments
Computes MC-truth decay length as the difference between collision.mcPosX() and track.vx() (daughter’s generated vertex = secondary vertex).
Secondary-vertex quantities are computed using this secondary vertex, and the mother momentum and mass.
Note: Mother mass currently implemented only for B⁺ and B⁰.
Includes Run 2 projected definitions and expected decay length for cross-checks.

PWGDQ/Tasks/dqEfficiency_withAssoc.cxx

In AnalysisDileptonTrack::runDileptonHadron:

Changes applied only for TCandidateType == VarManager::kBtoJpsiEEK.
If mcDecision = true, fill MC-truth B-mother quantities and compute MC secondary-vertex quantities using VarManager::FillTrackCollisionMC.
Additional MC-truth secondary-vertex variables and reconstructed-vertex errors added to the B-meson table.

PWGDQ/Core/VarManager.cxx

Units defined for the corresponding new values.

PWGDQ/Core/HistogramsLibrary.cxx

Added MC-truth histogram class in the dilepton-trackf subgroup for plotting the new quantities.

github-actions · 2025-11-19T14:27:08Z

O2 linter results: ❌ 496 errors, ⚠️ 805 warnings, 🔕 0 disabled

[PWGDQ] Please consider the following formatting changes to AliceO2Group#13890

iarsene · 2025-11-20T08:12:24Z

PWGDQ/Core/VarManager.h

+  values[kMCVertexingTauz] = (collision.mcPosZ() - track.vz()) * m / (TMath::Abs(MotherTrack.pz()) * o2::constants::physics::LightSpeedCm2NS);
+  values[kMCVertexingTauxy] = values[kMCVertexingLxy] * m / (MotherTrack.pt() * o2::constants::physics::LightSpeedCm2NS);


Maybe you need to add also the version for Tauxyz ?

iarsene · 2025-11-20T08:19:31Z

PWGDQ/Core/VarManager.h

+  values[kMCLxyExpected] = (MotherTrack.pt() / m) * (pdgLifetime * o2::constants::physics::LightSpeedCm2S);
+  values[kMCLxyzExpected] = (MotherTrack.p() / m) * (pdgLifetime * o2::constants::physics::LightSpeedCm2S);
+
+  values[kMCVertexingLzProjected] = ((track.vz() - collision.mcPosZ()) * MotherTrack.pz()) / TMath::Sqrt(MotherTrack.pz() * MotherTrack.pz());


in all this expression, what you need is just the sign of the pz component. So instead of pz / (sqrt(pz*pz)) should be just sign(pz()) or TMath::Sign(pz()). However, it seems that there is no straightforward sign function, so at least you could do just this: pz() / abs(pz())

iarsene · 2025-11-20T08:20:58Z

PWGDQ/Core/VarManager.h

+
+  values[kMCVertexingLzProjected] = ((track.vz() - collision.mcPosZ()) * MotherTrack.pz()) / TMath::Sqrt(MotherTrack.pz() * MotherTrack.pz());
+  values[kMCVertexingLxyProjected] = ((track.vx() - collision.mcPosX()) * MotherTrack.px()) + ((track.vy() - collision.mcPosY()) * MotherTrack.py());
+  values[kMCVertexingLxyProjected] = values[kVertexingLxyProjected] / TMath::Sqrt((MotherTrack.px() * MotherTrack.px()) + (MotherTrack.py() * MotherTrack.py()));


This part, TMath::Sqrt((MotherTrack.px() * MotherTrack.px()) + (MotherTrack.py() * MotherTrack.py()), should be just MotherTrack.pt()

Are you sure its not
values[kMCVertexingLxyProjected] = values[kVertexingLxyProjected] / TMath::Abs(MotherTrack.pt());

iarsene · 2025-11-20T08:22:01Z

PWGDQ/Core/VarManager.h

+  values[kMCVertexingLzProjected] = ((track.vz() - collision.mcPosZ()) * MotherTrack.pz()) / TMath::Sqrt(MotherTrack.pz() * MotherTrack.pz());
+  values[kMCVertexingLxyProjected] = ((track.vx() - collision.mcPosX()) * MotherTrack.px()) + ((track.vy() - collision.mcPosY()) * MotherTrack.py());
+  values[kMCVertexingLxyProjected] = values[kVertexingLxyProjected] / TMath::Sqrt((MotherTrack.px() * MotherTrack.px()) + (MotherTrack.py() * MotherTrack.py()));
+  values[kMCVertexingLxyzProjected] = ((track.vx() - collision.mcPosX()) * MotherTrack.px()) + ((track.vy() - collision.mcPosY()) * MotherTrack.py()) + ((track.vz() - collision.mcPosZ()) * MotherTrack.pz());


Here you compute this as the sum of kMCVertexingLxyProjected and the vz part of the scalar product

iarsene · 2025-11-20T08:22:31Z

PWGDQ/Core/VarManager.h

+  values[kMCVertexingLxyProjected] = ((track.vx() - collision.mcPosX()) * MotherTrack.px()) + ((track.vy() - collision.mcPosY()) * MotherTrack.py());
+  values[kMCVertexingLxyProjected] = values[kVertexingLxyProjected] / TMath::Sqrt((MotherTrack.px() * MotherTrack.px()) + (MotherTrack.py() * MotherTrack.py()));
+  values[kMCVertexingLxyzProjected] = ((track.vx() - collision.mcPosX()) * MotherTrack.px()) + ((track.vy() - collision.mcPosY()) * MotherTrack.py()) + ((track.vz() - collision.mcPosZ()) * MotherTrack.pz());
+  values[kMCVertexingLxyzProjected] = values[kMCVertexingLxyzProjected] / TMath::Sqrt((MotherTrack.px() * MotherTrack.px()) + (MotherTrack.py() * MotherTrack.py()) + (MotherTrack.pz() * MotherTrack.pz()));


Here, TMath::Sqrt((MotherTrack.px() * MotherTrack.px()) + (MotherTrack.py() * MotherTrack.py()) + (MotherTrack.pz() * MotherTrack.pz())) , should be just MotherTrack.p()

Abs(MotherTrack.p())?

p is just the mom vector magnitude, it can only be positive, no abs is not needed

iarsene · 2025-11-20T08:27:09Z

PWGDQ/Core/VarManager.h

+  values[kMCVertexingLxyzProjected] = ((track.vx() - collision.mcPosX()) * MotherTrack.px()) + ((track.vy() - collision.mcPosY()) * MotherTrack.py()) + ((track.vz() - collision.mcPosZ()) * MotherTrack.pz());
+  values[kMCVertexingLxyzProjected] = values[kMCVertexingLxyzProjected] / TMath::Sqrt((MotherTrack.px() * MotherTrack.px()) + (MotherTrack.py() * MotherTrack.py()) + (MotherTrack.pz() * MotherTrack.pz()));
+  values[kMCVertexingTauxyProjected] = values[kMCVertexingLxyProjected] * m / (MotherTrack.pt());
+  values[kMCVertexingTauxyProjectedNs] = values[kMCVertexingTauxyProjected] / o2::constants::physics::LightSpeedCm2NS;


you added this quantity in nano-sec just for the xy projection. Maybe you need it for the others too? Also, for the not projected Tau variables, you have them in nano-seconds, but this is not reflected in the name of the variable. Also, there you have them just in nanoseconds, and not the version which is in spatial units. I suggest to be consistent and have all of these variables.

The default or O2Physics is ns, so It seems unnessecary to specify this in the variable name of all tau variables in all tasks? The reason why I added it here is that "_Projected" are the same definitions in Run2, and at some point, in order to check consistenstsy between Run2 and Run3 I added the "_ProjectedNs" definition. So I havent really used these variables for anything else than Run2/Run3 comparisons.

generated/mctruth vertex for triplet implemeted

1db9cbd

torkjellsdatter requested review from alibuild, iarsene, lucamicheletti93 and mcoquet642 as code owners November 19, 2025 14:26

github-actions bot added the pwgdq label Nov 19, 2025

github-actions bot changed the title ~~dqEfficiency_withAssoc/VarManager: Add MC-truth secondary vertex for B→J/ψK triplet quantities~~ [PWGDQ] dqEfficiency_withAssoc/VarManager: Add MC-truth secondary vertex for B→J/ψK triplet quantities Nov 19, 2025

Please consider the following formatting changes

26ec073

alibuild mentioned this pull request Nov 19, 2025

[PWGDQ] Please consider the following formatting changes to #13890 torkjellsdatter/O2Physics#17

Merged

Merge pull request #17 from alibuild/alibot-cleanup-13890

ae33a8b

[PWGDQ] Please consider the following formatting changes to AliceO2Group#13890

iarsene reviewed Nov 20, 2025

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torkjellsdatter closed this Nov 20, 2025

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[PWGDQ] dqEfficiency_withAssoc/VarManager: Add MC-truth secondary vertex for B→J/ψK triplet quantities#13890

[PWGDQ] dqEfficiency_withAssoc/VarManager: Add MC-truth secondary vertex for B→J/ψK triplet quantities#13890
torkjellsdatter wants to merge 3 commits intoAliceO2Group:masterfrom
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		values[kMCVertexingTauz] = (collision.mcPosZ() - track.vz()) * m / (TMath::Abs(MotherTrack.pz()) * o2::constants::physics::LightSpeedCm2NS);
		values[kMCVertexingTauxy] = values[kMCVertexingLxy] * m / (MotherTrack.pt() * o2::constants::physics::LightSpeedCm2NS);

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torkjellsdatter commented Nov 19, 2025

Purpose

Changes

PWGDQ/Core/VarManager.h

PWGDQ/Tasks/dqEfficiency_withAssoc.cxx

PWGDQ/Core/VarManager.cxx

PWGDQ/Core/HistogramsLibrary.cxx

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github-actions bot commented Nov 19, 2025 •

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