[PWGHF] Support generator-only derived data without MC centrality (#18557)

Co-authored-by: Vít Kučera <26327373+vkucera@users.noreply.github.com>

Author: monamelop

PWGHF/TableProducer/derivedDataCreatorD0ToKPi.cxx

@@ -105,6 +105,7 @@ struct HfDerivedDataCreatorD0ToKPi {
   using SelectedCandidatesMcKfMl = soa::Filtered<soa::Join<aod::HfCand2ProngWPid, aod::HfCand2ProngKF, aod::HfCand2ProngMcRec, aod::HfSelD0, aod::HfMlD0>>;
   using MatchedGenCandidatesMc = soa::Filtered<soa::Join<aod::McParticles, aod::HfCand2ProngMcGen>>;
   using TypeMcCollisions = soa::Join<aod::McCollisions, aod::McCentFT0Ms>;
+  using TypeMcGenCollisions = aod::McCollisions;
 
   Filter filterSelectCandidates = aod::hf_sel_candidate_d0::isSelD0 >= 1 || aod::hf_sel_candidate_d0::isSelD0bar >= 1;
   Filter filterMcGenMatching = (nabs(aod::hf_cand_mc_flag::flagMcMatchGen) == static_cast<int8_t>(o2::hf_decay::hf_cand_2prong::DecayChannelMain::D0ToPiK)) || (acceptCorrelatedBkgs && aod::hf_cand_mc_flag::flagMcMatchGen != 0);
@@ -533,7 +534,7 @@ struct HfDerivedDataCreatorD0ToKPi {
   }
   PROCESS_SWITCH(HfDerivedDataCreatorD0ToKPi, processMcWithKFParticleMlAll, "Process MC with KFParticle and ML", false);
 
-  void processMcGenOnly(TypeMcCollisions const& mcCollisions,
+  void processMcGenOnly(TypeMcGenCollisions const& mcCollisions,
                         MatchedGenCandidatesMc const& mcParticles)
   {
     rowsCommon.processMcParticles(mcCollisions, mcParticlesPerMcCollision, mcParticles, Mass);

PWGHF/TableProducer/derivedDataCreatorDsToKKPi.cxx

@@ -100,6 +100,7 @@ struct HfDerivedDataCreatorDsToKKPi {
   using SelectedCandidatesMcMl = soa::Filtered<soa::Join<aod::HfCand3ProngWPidPiKa, aod::HfCand3ProngMcRec, aod::HfSelDsToKKPi, aod::HfMlDsToKKPi>>;
   using MatchedGenCandidatesMc = soa::Filtered<soa::Join<aod::McParticles, aod::HfCand3ProngMcGen>>;
   using TypeMcCollisions = soa::Join<aod::McCollisions, aod::McCentFT0Ms>;
+  using TypeMcGenCollisions = aod::McCollisions;
 
   Filter filterSelectCandidates = (aod::hf_sel_candidate_ds::isSelDsToKKPi & static_cast<int>(BIT(aod::SelectionStep::RecoMl - 1))) != 0 || (aod::hf_sel_candidate_ds::isSelDsToPiKK & static_cast<int>(BIT(aod::SelectionStep::RecoMl - 1))) != 0; // select candidates which passed all cuts at least up to RecoMl - 1
   Filter filterMcGenMatching = (nabs(aod::hf_cand_mc_flag::flagMcMatchGen) == static_cast<int8_t>(hf_decay::hf_cand_3prong::DecayChannelMain::DsToPiKK)) || (acceptCorrelatedBkgs && aod::hf_cand_mc_flag::flagMcMatchGen != 0);
@@ -411,7 +412,7 @@ struct HfDerivedDataCreatorDsToKKPi {
   }
   PROCESS_SWITCH(HfDerivedDataCreatorDsToKKPi, processMcMlAll, "Process MC with ML", false);
 
-  void processMcGenOnly(TypeMcCollisions const& mcCollisions,
+  void processMcGenOnly(TypeMcGenCollisions const& mcCollisions,
                         MatchedGenCandidatesMc const& mcParticles)
   {
     rowsCommon.processMcParticles(mcCollisions, mcParticlesPerMcCollision, mcParticles, Mass);

PWGHF/Utils/utilsDerivedData.h

@@ -168,11 +168,16 @@ struct HfProducesDerivedData : o2::framework::ProducesGroup {
   void fillTablesMcCollision(TMcCollision const& mcCollision)
   {
     if (conf->fillMcCollBase.value) {
+      float centFT0M{-1.f}; // Input without centrality: e.g. generator-only
+      if constexpr (requires { mcCollision.centFT0M(); }) {
+        // MC general: input includes centrality
+        centFT0M = mcCollision.centFT0M();
+      }
       rowMcCollBase(
         mcCollision.posX(),
         mcCollision.posY(),
         mcCollision.posZ(),
-        mcCollision.centFT0M());
+        centFT0M);
     }
     if (conf->fillMcCollId.value) {
       rowMcCollId(