[PWGHF/HFC] adding a new QA histogram for multiplicity (AliceO2Group#12654)

Author: deependra170598

PWGHF/HFC/TableProducer/correlatorDstarHadrons.cxx

@@ -196,12 +196,15 @@ struct HfCorrelatorDstarHadrons {
       LOGP(fatal, "One and only one process function must be enabled at a time.");
     }
 
+    AxisSpec axisSpecMultFT0M{binsMultiplicity, "Multiplicity in FT0M", "multFT0M"};
+
     invMassDstarParticle = -999.0;
     invMassD0Particle = -999.0;
     binNumber = -2;
 
     binningScheme = {{binsZVtx, binsMultiplicity}, true};
 
+    registry.add("QA/hMultFT0M", "Multiplicity distribution in FT0M", {HistType::kTH1D, {axisSpecMultFT0M}});
     registry.add("QA/hCandsPerCol", "Candidates per Collision", {HistType::kTH1D, {{100, 0.0, 100.0}}});
     registry.add("QA/hAssoTracksPerCol", "Tracks per Collision", {HistType::kTH1D, {{1000, 0.0, 1000.0}}});
     registry.add("QA/hCandsVsTracksPerCol", "Candidates vs Tracks per Collision", {HistType::kTHnSparseF, {{100, 0.0, 100.0}, {1000, 0.0, 1000.0}}});
@@ -239,6 +242,7 @@ struct HfCorrelatorDstarHadrons {
       } // endif
 
       registry.fill(HIST("hTriggerColCandPairCounts"), 1); // counting number of trigger particle
+      registry.fill(HIST("QA/hMultFT0M"), collision.multFT0M());
       registry.fill(HIST("QA/hCandsPerCol"), candidatesPerCol.size());
       registry.fill(HIST("QA/hAssoTracksPerCol"), tracksPerCol.size());
       registry.fill(HIST("QA/hCandsVsTracksPerCol"), candidatesPerCol.size(), tracksPerCol.size());