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stefanopolitano merged 1 commit into from
Nov 25, 2025
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[PWGHF] Add centrality information to MC collisions #13940

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57 changes: 49 additions & 8 deletions PWGHF/D2H/Tasks/taskXic0ToXiPi.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
#include "PWGHF/Core/HfHelper.h"
#include "PWGHF/DataModel/CandidateReconstructionTables.h"
#include "PWGHF/DataModel/CandidateSelectionTables.h"
#include "PWGLF/DataModel/mcCentrality.h"
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@stefanopolitano stefanopolitano Nov 24, 2025

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Hi @Tao-Fang ! Thanks for the development. This is fine for me, I just have a doubt about this line: do you really need to include the centrality from LF? Could you not use the centrality table from HF?

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@Tao-Fang Tao-Fang Nov 24, 2025

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Hi @stefanopolitano, thanks for your comment, I think the structure with mccentrality seems fine, which has same cite on other HF codes like candidateCreator3Prong.cxx, candidateCreatorCascade.cxx, and taskOmegac0ToOmegaPi.cxx

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@fcatalan92 fcatalan92 Nov 24, 2025

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Hi @stefanopolitano, the centrality from the LF task assigns a value to all generated events (also those not reconstructed) according to the generated particles in the FT0 acceptance, and it has been calibrated to match the data. This information is needed, e.g., to compute the event loss as a function of multiplicity, where you need the multiplicity interval also for events not reconstructed.
What is done in HF is to assign to the generated collision the centrality of the associated reconstructed collision with the larger number of contributors (to address split vertices). BTW, I'm not sure how much we can trust the centrality intervals obtained in this way, given also that we are using enriched HF MCs.

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@stefanopolitano stefanopolitano Nov 25, 2025

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Hi @fcatalan92! Thanks for the clarification (and sorry for the delay). Good for me!


#include "Common/Core/RecoDecay.h"
#include "Common/DataModel/Centrality.h"
Expand Down Expand Up @@ -81,6 +82,8 @@ struct HfTaskXic0ToXiPi {
using CollisionsWithFT0M = soa::Join<aod::Collisions, aod::EvSels, aod::CentFT0Ms>;
using CollisionsWithMcLabels = soa::Join<aod::Collisions, aod::McCollisionLabels, aod::EvSels>;

using McCollisionsCentFT0Ms = soa::Join<aod::McCollisions, aod::McCentFT0Ms>;

Filter filterSelectXic0Candidates = aod::hf_sel_toxipi::resultSelections == true;
Filter filterXicMatchedRec = nabs(aod::hf_cand_xic0_omegac0::flagMcMatchRec) == static_cast<int8_t>(BIT(aod::hf_cand_xic0_omegac0::DecayType::XiczeroToXiPi));
Filter filterXicMatchedGen = nabs(aod::hf_cand_xic0_omegac0::flagMcMatchGen) == static_cast<int8_t>(BIT(aod::hf_cand_xic0_omegac0::DecayType::XiczeroToXiPi));
Expand Down Expand Up @@ -124,18 +127,25 @@ struct HfTaskXic0ToXiPi {
const AxisSpec thnAxisGenPtD{thnConfigAxisGenPtD, "#it{p}_{T} (GeV/#it{c})"};
const AxisSpec thnAxisGenPtB{thnConfigAxisGenPtB, "#it{p}_{T}^{B} (GeV/#it{c})"};
const AxisSpec thnAxisNumPvContr{thnConfigAxisNumPvContr, "Number of PV contributors"};
const AxisSpec thnAxisCent{thnConfigAxisCent, "Centrality percentile"};

if (doprocessMcWithKFParticle || doprocessMcWithKFParticleMl || doprocessMcWithDCAFitter || doprocessMcWithDCAFitterMl) {
std::vector<AxisSpec> const axesAcc = {thnAxisGenPtD, thnAxisGenPtB, thnAxisY, thnAxisOrigin, thnAxisNumPvContr};
std::vector<AxisSpec> const axesAcc = {thnAxisGenPtD, thnAxisGenPtB, thnAxisY, thnAxisOrigin, thnAxisCent, thnAxisNumPvContr};
registry.add("hSparseAcc", "Thn for generated Xic0 from charm and beauty", HistType::kTHnSparseD, axesAcc);
registry.get<THnSparse>(HIST("hSparseAcc"))->Sumw2();

registry.add("hSparseAccWithRecoColl", "Gen. Xic0 from charm and beauty (associated to a reco collision)", HistType::kTHnSparseD, axesAcc);
registry.get<THnSparse>(HIST("hSparseAccWithRecoColl"))->Sumw2();

registry.add("hNumRecoCollPerMcColl", "Number of reco collisions associated to a mc collision;Num. reco. coll. per Mc coll.;", {HistType::kTH1D, {{10, -0.5, 9.5}}});
}

std::vector<AxisSpec> axes = {thnAxisMass, thnAxisPt, thnAxisY};
if (doprocessMcWithKFParticle || doprocessMcWithKFParticleMl) {
if (doprocessMcWithKFParticle || doprocessMcWithKFParticleMl || doprocessMcWithDCAFitter || doprocessMcWithDCAFitterMl) {
axes.push_back(thnAxisPtB);
axes.push_back(thnAxisOrigin);
axes.push_back(thnAxisMatchFlag);
axes.push_back(thnAxisCent);
axes.push_back(thnAxisNumPvContr);
}
if (applyMl) {
Expand Down Expand Up @@ -203,12 +213,12 @@ struct HfTaskXic0ToXiPi {
}
}

template <bool UseKfParticle, bool ApplyMl, typename CandType, typename CollType>
template <bool UseKfParticle, bool ApplyMl, typename CandType, typename CollType, typename McCollisionWithCents>
void processMc(const CandType& candidates,
Xic0Gen const& mcParticles,
TracksMc const&,
CollType const& collisions,
aod::McCollisions const&)
McCollisionWithCents const&)
{
// MC rec.
for (const auto& candidate : candidates) {
Expand All @@ -225,6 +235,8 @@ struct HfTaskXic0ToXiPi {
continue;
}

auto collision = candidate.template collision_as<CollisionsWithMcLabels>();
float const mcCent = o2::hf_centrality::getCentralityColl(collision.template mcCollision_as<McCollisionWithCents>());
auto numPvContributors = candidate.template collision_as<CollType>().numContrib();
double const ptXic = RecoDecay::pt(candidate.pxCharmBaryon(), candidate.pyCharmBaryon());
if constexpr (ApplyMl) {
Expand All @@ -236,6 +248,7 @@ struct HfTaskXic0ToXiPi {
candidate.ptBhadMotherPart(),
candidate.originMcRec(),
candidate.flagMcMatchRec(),
mcCent,
numPvContributors);
} else {
registry.fill(HIST("hMassVsPtVsPtBVsYVsOriginVsXic0Type"),
Expand All @@ -245,6 +258,7 @@ struct HfTaskXic0ToXiPi {
candidate.ptBhadMotherPart(),
candidate.originMcRec(),
candidate.flagMcMatchRec(),
mcCent,
numPvContributors);
}
}
Expand All @@ -258,6 +272,7 @@ struct HfTaskXic0ToXiPi {
auto ptGen = particle.pt();
auto yGen = particle.rapidityCharmBaryonGen();

float const mcCent = o2::hf_centrality::getCentralityColl(particle.template mcCollision_as<McCollisionWithCents>());
unsigned maxNumContrib = 0;
const auto& recoCollsPerMcColl = collisions.sliceBy(colPerMcCollision, particle.mcCollision().globalIndex());
for (const auto& recCol : recoCollsPerMcColl) {
Expand All @@ -270,6 +285,7 @@ struct HfTaskXic0ToXiPi {
-1.,
yGen,
RecoDecay::OriginType::Prompt,
mcCent,
maxNumContrib);
} else {
float const ptGenB = mcParticles.rawIteratorAt(particle.idxBhadMotherPart()).pt();
Expand All @@ -278,8 +294,33 @@ struct HfTaskXic0ToXiPi {
ptGenB,
yGen,
RecoDecay::OriginType::NonPrompt,
mcCent,
maxNumContrib);
}

registry.fill(HIST("hNumRecoCollPerMcColl"), recoCollsPerMcColl.size());

// fill sparse only for gen particles associated to a reconstructed collision
if (recoCollsPerMcColl.size() >= 1) {
if (particle.originMcGen() == RecoDecay::OriginType::Prompt) {
registry.fill(HIST("hSparseAccWithRecoColl"),
ptGen,
-1.,
yGen,
RecoDecay::OriginType::Prompt,
mcCent,
maxNumContrib);
} else {
float const ptGenB = mcParticles.rawIteratorAt(particle.idxBhadMotherPart()).pt();
registry.fill(HIST("hSparseAccWithRecoColl"),
ptGen,
ptGenB,
yGen,
RecoDecay::OriginType::NonPrompt,
mcCent,
maxNumContrib);
}
}
}
}

Expand Down Expand Up @@ -443,7 +484,7 @@ struct HfTaskXic0ToXiPi {
Xic0Gen const& mcParticles,
TracksMc const& tracks,
CollisionsWithMcLabels const& collisions,
aod::McCollisions const& mcCollisions)
McCollisionsCentFT0Ms const& mcCollisions)
{
processMc<false, false>(xic0CandidatesMc, mcParticles, tracks, collisions, mcCollisions);
}
Expand All @@ -453,7 +494,7 @@ struct HfTaskXic0ToXiPi {
Xic0Gen const& mcParticles,
TracksMc const& tracks,
CollisionsWithMcLabels const& collisions,
aod::McCollisions const& mcCollisions)
McCollisionsCentFT0Ms const& mcCollisions)
{
processMc<true, false>(xic0CandidatesMcKf, mcParticles, tracks, collisions, mcCollisions);
}
Expand All @@ -463,7 +504,7 @@ struct HfTaskXic0ToXiPi {
Xic0Gen const& mcParticles,
TracksMc const& tracks,
CollisionsWithMcLabels const& collisions,
aod::McCollisions const& mcCollisions)
McCollisionsCentFT0Ms const& mcCollisions)
{
processMc<false, true>(xic0CandidatesMlMc, mcParticles, tracks, collisions, mcCollisions);
}
Expand All @@ -473,7 +514,7 @@ struct HfTaskXic0ToXiPi {
Xic0Gen const& mcParticles,
TracksMc const& tracks,
CollisionsWithMcLabels const& collisions,
aod::McCollisions const& mcCollisions)
McCollisionsCentFT0Ms const& mcCollisions)
{
processMc<true, true>(xic0CandidatesMlMcKf, mcParticles, tracks, collisions, mcCollisions);
}
Expand Down
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