[PWGLF] Adding event and track level qa histograms for MFT analysis (#16717)

Co-authored-by: ALICE Action Bot <alibuild@cern.ch>

Author: tutripat

PWGLF/Tasks/GlobalEventProperties/PseudorapidityDensityMFT.cxx

@@ -400,7 +400,8 @@ struct PseudorapidityDensityMFT {
   Configurable<bool> useTriggerTVX{"useTriggerTVX", true, "Require kIsTriggerTVX in processGenReco"};
   Configurable<bool> useNoTimeFrameBorderCut{"useNoTimeFrameBorderCut", true, "Require kNoTimeFrameBorder in processGenReco"};
   Configurable<bool> useNoITSROFrameBorderCut{"useNoITSROFrameBorderCut", true, "Require kNoITSROFrameBorder in processGenReco"};
-
+  AxisSpec multAxisRecoMFT = {multBinning, "N_{ch}^{reco,MFT}"};
+  AxisSpec multAxisGenMFT = {multBinning, "N_{ch}^{gen,MFT}"};
   HistogramRegistry registry{
     "registry",
     {
@@ -630,6 +631,22 @@ struct PseudorapidityDensityMFT {
       registry.add({"Purity/reco/PNchMFT_afterCuts",
                     ";N_{trk}^{MFT} (selected);events",
                     {HistType::kTH1F, {multAxis}}});
+      // MC P(Nch) objects for MFT multiplicity unfolding/correction.
+      // Generator multiplicity: primary charged particles in the MFT acceptance,
+      // with generated INEL>0 defined from the central estimator.
+      // Reco multiplicity: selected reassociated MFT tracks for matched accepted reco events.
+      registry.add({"PNchMC/gen_inelgt0",
+                    ";N_{ch}^{gen,MFT};events",
+                    {HistType::kTH1F, {multAxisGenMFT}}});
+
+      registry.add({"PNchMC/reco_sel8_inelgt0",
+                    ";N_{ch}^{reco,MFT};events",
+                    {HistType::kTH1F, {multAxisRecoMFT}}});
+
+      registry.add({"PNchMC/responseMatrix",
+                    ";N_{ch}^{reco,MFT};N_{ch}^{gen,MFT};events",
+                    {HistType::kTH2F, {multAxisRecoMFT, multAxisGenMFT}}});
+
       registry.add({"Purity/DCAyVsDCAx_Right",
                     ";DCA_{x} (cm);DCA_{y} (cm)",
                     {HistType::kTH2F, {dcaXAxis, dcaYAxis}}});
@@ -1214,6 +1231,27 @@ struct PseudorapidityDensityMFT {
                     " ; N_{Trk}^{nonamb}",
                     {HistType::kTH1F, {{701, -0.5, 700.5}}}}); //
 
+      // Event-level P(Nch) distributions for reassociated MFT tracks.
+      // Fill once per collision after counting selected reassociated MFT tracks.
+      registry.add({"PNch/MFT_sel8",
+                    ";N_{ch}^{MFT};events",
+                    {HistType::kTH1F, {multAxis}}});
+      registry.add({"PNch/MFT_sel8_inelgt0",
+                    ";N_{ch}^{MFT};events",
+                    {HistType::kTH1F, {multAxis}}});
+      registry.add({"PNch/MFT_sel8_inelfwdgt0",
+                    ";N_{ch}^{MFT};events",
+                    {HistType::kTH1F, {multAxis}}});
+      registry.add({"PNch/MFT_sel8_inelgt0_nonamb",
+                    ";N_{ch}^{MFT, nonamb};events",
+                    {HistType::kTH1F, {multAxis}}});
+      registry.add({"PNch/MFT_sel8_inelgt0_amb",
+                    ";N_{ch}^{MFT, amb};events",
+                    {HistType::kTH1F, {multAxis}}});
+      registry.add({"PNch/MFTZvtx_sel8_inelgt0",
+                    ";N_{ch}^{MFT};#it{z}_{vtx} (cm);events",
+                    {HistType::kTH2F, {multAxis, zAxis}}});
+
       registry.add({"Tracks/Control/amb/AmbTracksPhiEta",
                     "; #varphi; #eta; tracks",
                     {HistType::kTH2F, {phiAxis, etaBinning}}}); //
@@ -1542,6 +1580,10 @@ struct PseudorapidityDensityMFT {
     std::unordered_set<int> eventsInelMFT;
     std::unordered_set<int> eventsInel;
 
+    int64_t nMFTSelected{0};
+    int64_t nMFTSelectedAmb{0};
+    int64_t nMFTSelectedNonAmb{0};
+
     const auto fillDataCut = [&](DataCutBin bin) {
       registry.fill(HIST("EventSelectionData"), static_cast<int>(bin));
     };
@@ -1655,6 +1697,13 @@ struct PseudorapidityDensityMFT {
       if (failTrackCuts) {
         continue;
       }
+      ++nMFTSelected;
+      if (retrack.ambDegree() > SingleCompatibleCollision) {
+        ++nMFTSelectedAmb;
+      } else if (retrack.ambDegree() == SingleCompatibleCollision) {
+        ++nMFTSelectedNonAmb;
+      }
+
       registry.fill(HIST("Tracks/Control/TrackAmbDegree"),
                     retrack.ambDegree());
       registry.fill(HIST("Tracks/Control/DCAXY"), retrack.bestDCAXY());
@@ -1771,6 +1820,17 @@ struct PseudorapidityDensityMFT {
     registry.fill(HIST("Tracks/Control/nonamb/nTrkNonAmb"), j);
     registry.fill(HIST("Tracks/Control/woOrp/nTrk"), k);
     registry.fill(HIST("hNumCollisions_Inel"), 1, eventsInel.size());
+
+    registry.fill(HIST("PNch/MFT_sel8"), nMFTSelected);
+    if (midtracks.size() > 0) {
+      registry.fill(HIST("PNch/MFT_sel8_inelgt0"), nMFTSelected);
+      registry.fill(HIST("PNch/MFTZvtx_sel8_inelgt0"), nMFTSelected, z);
+      registry.fill(HIST("PNch/MFT_sel8_inelgt0_nonamb"), nMFTSelectedNonAmb);
+      registry.fill(HIST("PNch/MFT_sel8_inelgt0_amb"), nMFTSelectedAmb);
+      if (nMFTSelected > 0) {
+        registry.fill(HIST("PNch/MFT_sel8_inelfwdgt0"), nMFTSelected);
+      }
+    }
   }
 
   void processMultReassoc(CollwEv::iterator const& collision,
@@ -2413,6 +2473,7 @@ struct PseudorapidityDensityMFT {
     bool onlyVzGt0 = false;           // EtaZvtxGen_gt0t
     bool atLeastOneSel8Vz = false;    // EtaZvtxGen
     bool atLeastOneSel8VzGt0 = false; // EtaZvtxGen_gt0
+    bool hasRecoCollisionForPNch{false};
 
     const auto fillGenRecoCut = [&](GenRecoCutBin bin) {
       registry.fill(HIST("EventsRecoCuts_GenReco"), static_cast<int>(bin));
@@ -2567,6 +2628,7 @@ struct PseudorapidityDensityMFT {
       acceptedRecoCols.insert(recoCol);
       recoCollisionIds.insert(recoCol);
       trueMCCollisionIds.insert(mcCol);
+      hasRecoCollisionForPNch = true;
 
       if (mcCol >= 0) {
         recoToMc[recoCol] = mcCol;
@@ -2603,7 +2665,9 @@ struct PseudorapidityDensityMFT {
     int64_t woOrpCount = 0;
     bool filledRight = false;
     bool filledWrong = false;
-    int nMftSelectedAfterCuts = 0;
+    int64_t nMftSelectedAfterCuts{0};
+    int64_t nRecoMFTSelectedForPNch{0};
+    int64_t nGenPrimaryChargedMFT{0};
     std::unordered_set<int> uniqueBestRecoCols;
 
     if (tracks.size() > 0) {
@@ -2689,6 +2753,11 @@ struct PseudorapidityDensityMFT {
           failDCAzCut = useDCAzCut && (std::abs(dcaZCut) > maxDCAz);
           // std::cout <<" dcaZReco " <<dcaZReco<< "  maxDCAz "<<maxDCAz<<std::endl;
         }
+        if (failDCAzCut) {
+          continue;
+        }
+
+        ++nRecoMFTSelectedForPNch;
 
         const bool hasMcLabel = track.has_mcParticle();
         const bool isFakeByLabel = hasMcLabel ? (track.mcMask() != 0) : false;
@@ -3227,6 +3296,26 @@ struct PseudorapidityDensityMFT {
             }
           }
         }
+        if (particle.isPhysicalPrimary()) {
+
+          ++nGenPrimaryChargedMFT;
+        }
+      }
+    }
+    if ((mcCollision.posZ() >= cfgVzCut1) && (mcCollision.posZ() <= cfgVzCut2)) {
+      if (nChargedCentral > 0) {
+
+        registry.fill(HIST("PNchMC/gen_inelgt0"),
+                      nGenPrimaryChargedMFT);
+
+        if (hasRecoCollisionForPNch) {
+          registry.fill(HIST("PNchMC/reco_sel8_inelgt0"),
+                        nRecoMFTSelectedForPNch);
+
+          registry.fill(HIST("PNchMC/responseMatrix"),
+                        nRecoMFTSelectedForPNch,
+                        nGenPrimaryChargedMFT);
+        }
       }
     }
   }