[PWGHF] XicToXiPiPi: Add DecayLengthMcGen column (#12627)

Author: JaeYoonCHO

PWGHF/DataModel/CandidateReconstructionTables.h

@@ -1918,6 +1918,7 @@ DECLARE_SOA_COLUMN(FlagMcMatchRec, flagMcMatchRec, int8_t); // reconstruction le
 DECLARE_SOA_COLUMN(FlagMcMatchGen, flagMcMatchGen, int8_t); // generator level
 DECLARE_SOA_COLUMN(OriginMcRec, originMcRec, int8_t);
 DECLARE_SOA_COLUMN(OriginMcGen, originMcGen, int8_t);
+DECLARE_SOA_COLUMN(DecayLengthMcGen, decayLengthMcGen, float);
 // Residuals and pulls
 DECLARE_SOA_COLUMN(PtResidual, ptResidual, float);
 DECLARE_SOA_COLUMN(PResidual, pResidual, float);
@@ -2025,7 +2026,8 @@ DECLARE_SOA_TABLE(HfCandXicMcRec, "AOD", "HFCANDXICMCREC",
 DECLARE_SOA_TABLE(HfCandXicMcGen, "AOD", "HFCANDXICMCGEN",
                   hf_cand_xic_to_xi_pi_pi::FlagMcMatchGen,
                   hf_cand_xic_to_xi_pi_pi::OriginMcGen,
-                  hf_cand::PdgBhadMotherPart);
+                  hf_cand::PdgBhadMotherPart,
+                  hf_cand_xic_to_xi_pi_pi::DecayLengthMcGen);
 
 // table with residuals and pulls of PV
 DECLARE_SOA_TABLE(HfCandXicResid, "AOD", "HFCANDXICRESID",

PWGHF/TableProducer/candidateCreatorXicToXiPiPi.cxx

@@ -912,6 +912,7 @@ struct HfCandidateCreatorXicToXiPiPiExpressions {
     int8_t sign = 0;
     int8_t flag = 0;
     int8_t origin = RecoDecay::OriginType::None;
+    float decayLengthGen = -999.f;
     int8_t nPionsDecayed = 0;
     int8_t nInteractionsWithMaterial = 0;
     // for resonance matching
@@ -1088,7 +1089,7 @@ struct HfCandidateCreatorXicToXiPiPiExpressions {
       if (rejectionMask != 0) {
         // at least one event selection not satisfied --> reject all particles from this collision
         for (unsigned int i = 0; i < mcParticlesPerMcColl.size(); ++i) {
-          rowMcMatchGen(-99, -99, -99);
+          rowMcMatchGen(-99, -99, -99, decayLengthGen);
         }
         continue;
       }
@@ -1134,13 +1135,18 @@ struct HfCandidateCreatorXicToXiPiPiExpressions {
         // Check whether the charm baryon is non-prompt (from a b quark).
         if (flag != 0) {
           origin = RecoDecay::getCharmHadronOrigin(mcParticles, particle, false, &idxBhadMothers);
+          // Calculate the decay length of the generated particle
+          auto dau0 = particle.template daughters_as<aod::McParticles>().begin();
+          const std::array vtxDau{dau0.vx(), dau0.vy(), dau0.vz()};
+          const std::array vtxPV{mcCollision.posX(), mcCollision.posY(), mcCollision.posZ()};
+          decayLengthGen = RecoDecay::distance(vtxPV, vtxDau);
         }
         // Fill table
         if (origin == RecoDecay::OriginType::NonPrompt) {
           auto bHadMother = mcParticles.rawIteratorAt(idxBhadMothers[0]);
-          rowMcMatchGen(flag, origin, bHadMother.pdgCode());
+          rowMcMatchGen(flag, origin, bHadMother.pdgCode(), decayLengthGen);
         } else {
-          rowMcMatchGen(flag, origin, 0);
+          rowMcMatchGen(flag, origin, 0, decayLengthGen);
         }
       } // close loop over generated particles
     } // close loop over McCollisions

PWGHF/TableProducer/treeCreatorXicToXiPiPi.cxx

@@ -334,7 +334,8 @@ DECLARE_SOA_TABLE(HfCandXicToXiPiPiFullPs, "AOD", "HFXICXI2PIFULLP",
                   full::Pt,
                   full::Eta,
                   full::Phi,
-                  full::Y);
+                  full::Y,
+                  hf_cand_xic_to_xi_pi_pi::DecayLengthMcGen);
 } // namespace o2::aod
 
 /// Writes the full information in an output TTree
@@ -723,7 +724,8 @@ struct HfTreeCreatorXicToXiPiPi {
           particle.pt(),
           particle.eta(),
           particle.phi(),
-          RecoDecay::y(particle.pVector(), o2::constants::physics::MassXiCPlus));
+          RecoDecay::y(particle.pVector(), o2::constants::physics::MassXiCPlus),
+          particle.decayLengthMcGen());
       }
     }
   }
@@ -776,7 +778,8 @@ struct HfTreeCreatorXicToXiPiPi {
           particle.pt(),
           particle.eta(),
           particle.phi(),
-          RecoDecay::y(particle.pVector(), o2::constants::physics::MassXiCPlus));
+          RecoDecay::y(particle.pVector(), o2::constants::physics::MassXiCPlus),
+          particle.decayLengthMcGen());
       }
     }
   }