[PWGEM/PhotonMeson] Add true eta from HS and WD histograms (#10630)

Co-authored-by: Nicolas Strangmann <nicolas.strangmann@.cern.ch>

Author: nstrangm

PWGEM/PhotonMeson/Utils/NMHistograms.h

@@ -51,6 +51,8 @@ void addNMHistograms(HistogramRegistry* fRegistry, bool isMC, const char* pairna
     fRegistry->add("Pair/Pi0/hs_FromSameGamma", "Two clusters from same gamma that is a pi0 daughter (conversion)", kTHnSparseD, {axis_mass, axis_pt}, true);
     fRegistry->add("Pair/Eta/hs_FromSameGamma", "Two clusters from same gamma that is a eta daughter (conversion)", kTHnSparseD, {axis_mass, axis_pt}, true);
     fRegistry->add("Pair/Eta/hs_Primary", "rec. true eta", kTHnSparseD, {axis_mass, axis_pt}, true);
+    fRegistry->add("Pair/Eta/hs_FromWD", "rec. true eta from weak decay", kTHnSparseD, {axis_mass, axis_pt}, true);
+    fRegistry->add("Pair/Eta/hs_FromHS", "rec. true eta from hadronic shower in material", kTHnSparseD, {axis_mass, axis_pt}, true);
 
     const AxisSpec axis_rapidity{{0.0, +0.8, +0.9}, "rapidity |y|"};
     fRegistry->add("Generated/Pi0/hPt", "pT;p_{T} (GeV/c)", kTH1F, {axis_pt}, true);
@@ -74,9 +76,9 @@ void fillTruePairInfo(HistogramRegistry* fRegistry, TDiphoton const& v12, TMCPar
 {
   int pdg = std::abs(mcparticle.pdgCode());
   float weight = eventWeight;
+  int motherid_strhad = IsFromWD(mcparticle.template emmcevent_as<TMCCollisions>(), mcparticle, mcparticles);
   switch (pdg) {
     case 111: {
-      int motherid_strhad = IsFromWD(mcparticle.template emmcevent_as<TMCCollisions>(), mcparticle, mcparticles);
       if (mcparticle.isPhysicalPrimary() || mcparticle.producedByGenerator()) {
         fRegistry->fill(HIST("Pair/Pi0/hs_Primary"), v12.M(), v12.Pt(), weight);
       } else if (motherid_strhad > 0) {
@@ -93,6 +95,10 @@ void fillTruePairInfo(HistogramRegistry* fRegistry, TDiphoton const& v12, TMCPar
     case 221: {
       if (mcparticle.isPhysicalPrimary() || mcparticle.producedByGenerator()) {
         fRegistry->fill(HIST("Pair/Eta/hs_Primary"), v12.M(), v12.Pt(), weight);
+      } else if (motherid_strhad > 0) {
+        fRegistry->fill(HIST("Pair/Eta/hs_FromWD"), v12.M(), v12.Pt(), weight);
+      } else {
+        fRegistry->fill(HIST("Pair/Eta/hs_FromHS"), v12.M(), v12.Pt(), weight);
       }
       break;
     }