[PWGLF] Fix event selection in MC table for spin correlation and add new process function for high mass resonance ananlysis (#16220)

Author: skundu692

PWGLF/TableProducer/Strangeness/lambdaspincorrelation.cxx

@@ -114,7 +114,7 @@ struct lambdaspincorrelation {
   {
     rctChecker.init(rctCut.cfgEvtRCTFlagCheckerLabel, rctCut.cfgEvtRCTFlagCheckerZDCCheck, rctCut.cfgEvtRCTFlagCheckerLimitAcceptAsBad);
     AxisSpec thnAxisInvMass{iMNbins, lbinIM, hbinIM, "#it{M} (GeV/#it{c}^{2})"};
-    histos.add("hEvtSelInfo", "hEvtSelInfo", kTH1F, {{5, 0, 5.0}});
+    histos.add("hEvtSelInfo", "hEvtSelInfo", kTH1F, {{10, 0, 10.0}});
     histos.add("hLambdaMass", "hLambdaMass", kTH1F, {thnAxisInvMass});
     histos.add("hV0Info", "hV0Info", kTH1F, {{5, 0, 5.0}});
   }
@@ -234,6 +234,46 @@ struct lambdaspincorrelation {
     return {lambdaTag, aLambdaTag, true}; // Valid candidate
   }
 
+  std::tuple<int, int, bool> getLambdaTagsMC(const auto& v0, const auto& collision)
+  {
+    auto postrack = v0.template posTrack_as<AllTrackCandidatesMC>();
+    auto negtrack = v0.template negTrack_as<AllTrackCandidatesMC>();
+
+    int lambdaTag = 0;
+    int aLambdaTag = 0;
+
+    const auto signpos = postrack.sign();
+    const auto signneg = negtrack.sign();
+
+    if (signpos < 0 || signneg > 0) {
+      return {0, 0, false};
+    }
+
+    if (isSelectedV0Daughter(v0, postrack, 0) &&
+        isSelectedV0Daughter(v0, negtrack, 1) &&
+        v0.mLambda() > lbinIM &&
+        v0.mLambda() < hbinIM) {
+      lambdaTag = 1;
+    }
+
+    if (isSelectedV0Daughter(v0, negtrack, 0) &&
+        isSelectedV0Daughter(v0, postrack, 1) &&
+        v0.mAntiLambda() > lbinIM &&
+        v0.mAntiLambda() < hbinIM) {
+      aLambdaTag = 1;
+    }
+
+    if (!lambdaTag && !aLambdaTag) {
+      return {0, 0, false};
+    }
+
+    if (!selectionV0(collision, v0)) {
+      return {0, 0, false};
+    }
+
+    return {lambdaTag, aLambdaTag, true};
+  }
+
   ROOT::Math::PxPyPzMVector lambda, antiLambda, proton, pion, antiProton, antiPion;
   ROOT::Math::PxPyPzMVector lambdaDummy, pionDummy, protonDummy;
 
@@ -474,6 +514,7 @@ struct lambdaspincorrelation {
                   ResoV0s const& V0s,
                   aod::McParticles const&)
   {
+    histos.fill(HIST("hEvtSelInfo"), 0.5);
     if (collisions.size() == 1) {
 
       for (const auto& collision : collisions) {
@@ -498,7 +539,7 @@ struct lambdaspincorrelation {
         auto vz = collision.posZ();
         int occupancy = collision.trackOccupancyInTimeRange();
 
-        histos.fill(HIST("hEvtSelInfo"), 0.5);
+        histos.fill(HIST("hEvtSelInfo"), 1.5);
 
         if (std::abs(collision.posZ()) < cfgCutVertex &&
             (!rctCut.requireRCTFlagChecker || rctChecker(collision)) &&
@@ -513,29 +554,27 @@ struct lambdaspincorrelation {
             (!useGoodITSLayersAll || collision.selection_bit(o2::aod::evsel::kIsGoodITSLayersAll)) &&
             occupancy < cfgCutOccupancy) {
 
-          histos.fill(HIST("hEvtSelInfo"), 1.5);
+          histos.fill(HIST("hEvtSelInfo"), 2.5);
 
           for (const auto& v0 : V0s) {
-
-            auto [lambdaTag, aLambdaTag, isValid] = getLambdaTags(v0, collision);
+            histos.fill(HIST("hEvtSelInfo"), 3.5); // all V0s seen
+            auto [lambdaTag, aLambdaTag, isValid] = getLambdaTagsMC(v0, collision);
 
             if (isValid) {
-
+              histos.fill(HIST("hEvtSelInfo"), 4.5); // passed getLambdaTagsMC
               auto postrack1 = v0.template posTrack_as<AllTrackCandidatesMC>();
               auto negtrack1 = v0.template negTrack_as<AllTrackCandidatesMC>();
 
               // Reject candidates whose reconstructed daughters are not MC-labelled.
               if (!postrack1.has_mcParticle() || !negtrack1.has_mcParticle()) {
+                histos.fill(HIST("hEvtSelInfo"), 5.5); // rejected: no MC label
                 continue;
               }
 
-              auto mcPos = postrack1.mcParticle();
-              auto mcNeg = negtrack1.mcParticle();
+              // auto mcPos = postrack1.mcParticle();
+              // auto mcNeg = negtrack1.mcParticle();
 
-              // Reject gap/background-event daughters.
-              if (mcPos.fromBackgroundEvent() || mcNeg.fromBackgroundEvent()) {
-                continue;
-              }
+              histos.fill(HIST("hEvtSelInfo"), 6.5); // rejected: no MC label
 
               if (lambdaTag) {
                 histos.fill(HIST("hV0Info"), 0.5);
@@ -626,7 +665,7 @@ struct lambdaspincorrelation {
           }
 
           if (numbV0 > 1 && v0Cospa.size() > 1) {
-            histos.fill(HIST("hEvtSelInfo"), 2.5);
+            histos.fill(HIST("hEvtSelInfo"), 7.5);
 
             lambdaEventmc(centrality, vz);
             auto indexEvent = lambdaEventmc.lastIndex();