Store leg kinematics in photon mixing pool. Replace EMPair with a local PhotonWithLegs struct in the EventMixingHandler pool

Author: Stefanie Mrozinski

PWGEM/PhotonMeson/Tasks/photonhbt.cxx

@@ -302,6 +302,8 @@ struct Photonhbt {
     Configurable<float> cfgMaxAsymmetry{"cfgMaxAsymmetry", -1.f, "max |p_{T, 1} - p_{T, 2}|/(p_{T, 1} + p_{T, 2}) asymmetry cut"};
   } ggpaircuts;
 
+  
+
   EMPhotonEventCut fEMEventCut;
   struct : ConfigurableGroup {
     std::string prefix = "eventcut_group";
@@ -598,6 +600,21 @@ struct Photonhbt {
     float alphaTrue = 0.f;
   };
 
+  struct PhotonWithLegs {
+  float fPt{0}, fEta{0}, fPhi{0};
+  float fVx{0}, fVy{0}, fVz{0};
+  std::array<float, 2> fLegPt{}, fLegEta{}, fLegPhi{}; // [0] = e+, [1] = e-
+  float pt() const { return fPt; }
+  float eta() const { return fEta; }
+  float phi() const { return fPhi; }
+  float vx() const { return fVx; }
+  float vy() const { return fVy; }
+  float vz() const { return fVz; }
+  float legEta(int i) const { return fLegEta[i]; }
+  float legPhi(int i) const { return fLegPhi[i]; }
+  float legPt(int i) const { return fLegPt[i]; }
+};
+
   std::map<std::tuple<int, int, int, int>, std::deque<std::vector<TruthGamma>>> truthGammaPool;
 
   void addSinglePhotonQAHistogramsForStep(const std::string& path)
@@ -1833,15 +1850,23 @@ struct Photonhbt {
                               pos1.eta(), ele1.eta(),
                               pos2.eta(), ele2.eta()),
           obs.deta, obs.dphi, obs.kt);
-        auto addToPool = [&](auto const& g) {
-          if (usedPhotonIdsPerCol.insert(g.globalIndex()).second) {
-            EMPair gtmp(g.pt(), g.eta(), g.phi(), 0.f);
-            gtmp.setConversionPointXYZ(g.vx(), g.vy(), g.vz());
-            emh1->AddTrackToEventPool(keyDFCollision, gtmp);
-          }
-        };
-        addToPool(g1);
-        addToPool(g2);
+    auto addToPool = [&](auto const& g, auto const& pos, auto const& ele) {
+  if (usedPhotonIdsPerCol.insert(g.globalIndex()).second) {
+    PhotonWithLegs p;
+    p.fPt = g.pt();
+    p.fEta = g.eta();
+    p.fPhi = g.phi();
+    p.fVx = g.vx();
+    p.fVy = g.vy();
+    p.fVz = g.vz();
+    p.fLegPt = {static_cast<float>(pos.pt()), static_cast<float>(ele.pt())};
+    p.fLegEta = {static_cast<float>(pos.eta()), static_cast<float>(ele.eta())};
+    p.fLegPhi = {static_cast<float>(pos.phi()), static_cast<float>(ele.phi())};
+    emh1->AddTrackToEventPool(keyDFCollision, p);
+  }
+};
+addToPool(g1, pos1, ele1);
+addToPool(g2, pos2, ele2);
       }
       if (qaflags.doSinglePhotonQa) {
         for (const auto& g : photons1Coll) {
@@ -2060,15 +2085,23 @@ struct Photonhbt {
           }
         }
 
-        auto addToPool = [&](auto const& g) {
-          if (usedPhotonIdsPerCol.insert(g.globalIndex()).second) {
-            EMPair gtmp(g.pt(), g.eta(), g.phi(), 0.f);
-            gtmp.setConversionPointXYZ(g.vx(), g.vy(), g.vz());
-            emh1->AddTrackToEventPool(keyDFCollision, gtmp);
-          }
-        };
-        addToPool(g1);
-        addToPool(g2);
+     auto addToPool = [&](auto const& g, auto const& pos, auto const& ele) {
+  if (usedPhotonIdsPerCol.insert(g.globalIndex()).second) {
+    PhotonWithLegs p;
+    p.fPt = g.pt();
+    p.fEta = g.eta();
+    p.fPhi = g.phi();
+    p.fVx = g.vx();
+    p.fVy = g.vy();
+    p.fVz = g.vz();
+    p.fLegPt = {static_cast<float>(pos.pt()), static_cast<float>(ele.pt())};
+    p.fLegEta = {static_cast<float>(pos.eta()), static_cast<float>(ele.eta())};
+    p.fLegPhi = {static_cast<float>(pos.phi()), static_cast<float>(ele.phi())};
+    emh1->AddTrackToEventPool(keyDFCollision, p);
+  }
+};
+addToPool(g1, pos1, ele1);
+addToPool(g2, pos2, ele2);
       }
       if (qaflags.doSinglePhotonQa) {
         for (const auto& g : photonsColl) {
@@ -2516,7 +2549,7 @@ struct Photonhbt {
   } // end runTruthEfficiency
 
   using MyEMH = o2::aod::pwgem::dilepton::utils::EventMixingHandler<
-    std::tuple<int, int, int, int>, std::pair<int, int>, EMPair>;
+    std::tuple<int, int, int, int>, std::pair<int, int>, PhotonWithLegs>;
 
   MyEMH* emh1 = nullptr;
   MyEMH* emh2 = nullptr;