add mixed event, swap custom functions for recodecay

Author: GiorgioAlbertoLucia

PWGLF/TableProducer/Strangeness/doubleOmegaTreeCreator.cxx

@@ -49,6 +49,7 @@
 #include <TPDGCode.h>
 
 #include <algorithm>
+#include <chrono>
 #include <array>
 #include <chrono>
 #include <cmath>
@@ -106,6 +107,36 @@ struct MixingSeed {
   BuiltKaonCandidate kaon;
 };
 
+struct BuiltKaonCandidate {
+  o2::track::TrackParCov track;
+  int64_t trackId = -1;
+  int8_t sign = 0;
+  float tpcNSigma = -999.f; // -999 when TPC is unavailable.
+  float tofNSigma = -999.f; // -999 when TOF is unavailable.
+  uint32_t detectorMap = 0;
+};
+
+// Omega, Lambda and kaon candidates of one collision, built once and paired afterwards.
+// Lambdas and kaons are stored per charge of the Omega they can be paired with (see chargeIndex).
+struct CollisionCandidates {
+  std::array<float, 3> primaryVertex{};
+  std::vector<BuiltOmegaCandidate> omegas;
+  std::array<std::vector<BuiltLambdaCandidate>, 2> lambdas;
+  std::array<std::vector<BuiltKaonCandidate>, 2> kaons;
+};
+
+// Same-event double-Omega candidate used as a seed of the candidate-level event mixing. Seeds are
+// kept in a pool across dataframes, so they store copies of their daughters, with the collision and
+// track indices made unique across dataframes (see uniqueIndex).
+struct MixingSeed {
+  int64_t collisionId = -1;
+  std::array<float, 3> primaryVertex{};
+  float bz = 0.f;
+  BuiltOmegaCandidate omega;
+  BuiltLambdaCandidate lambda;
+  BuiltKaonCandidate kaon;
+};
+
 struct doubleOmegaTreeCreator {
   Produces<aod::DoubleOmegaTable> doubleOmegaTable;
   Produces<aod::DoubleOmegaTableMC> doubleOmegaTableMC;
@@ -135,6 +166,7 @@ struct doubleOmegaTreeCreator {
   std::vector<int64_t> reconstructedDoubleOmegaIds;
 
   Preslice<TracksFullMC> tracksPerCollision = aod::track::collisionId;
+  Preslice<TracksFull> tracksPerCollisionData = aod::track::collisionId;
   Preslice<aod::Cascades> rawCascadesPerCollision = aod::cascade::collisionId;
   Preslice<aod::V0s> rawV0sPerCollision = aod::v0::collisionId;
   Preslice<aod::DOmegaTracks> derivedTracksPerCollision = aod::domega::dOmegaCollId;