better tuning of multiplicity dependent parameters in regional tracki…

…ng and proto-track filter

RecoHI/HiTracking/plugins/HITrackingRegionForPrimaryVtxProducer.h

@@ -61,22 +61,22 @@ class HITrackingRegionForPrimaryVtxProducer : public TrackingRegionProducer {
 
     int estMult = estimateMultiplicity(ev, es);
 
-    // fit from MC information
-    float aa = 1.90935e-04;
-    float bb = -2.90167e-01;
-    float cc = 3.86125e+02;
-    
+    // from MC relating first layer pixel hits to "findable" sim tracks with pt>1 GeV
+    float cc = -38.6447;
+    float bb = 0.0581765;
+    float aa = 1.34306e-06;
+
     float estTracks = aa*estMult*estMult+bb*estMult+cc;
 
     LogTrace("heavyIonHLTVertexing")<<"[HIVertexing]";
     LogTrace("heavyIonHLTVertexing")<<" [HIVertexing: hits in the 1. layer:" << estMult << "]";
     LogTrace("heavyIonHLTVertexing")<<" [HIVertexing: estimated number of tracks:" << estTracks << "]";
 
-    float regTracking = 1600.;  //if we have more tracks -> regional tracking (was 400)
+    float regTracking = 60.;  //if we have more tracks -> regional tracking
     float etaB = 10.;
     float phiB = TMath::Pi()/2.;
 
-    float decEta = estTracks/2400.; // (was 600)
+    float decEta = estTracks/90.;
     etaB = 2.5/decEta;
 
     if(estTracks>regTracking) {
@@ -87,10 +87,10 @@ class HITrackingRegionForPrimaryVtxProducer : public TrackingRegionProducer {
     }
 
     float minpt = thePtMin;
-    float varPtCutoff = 2000; //cutoff
+    float varPtCutoff = 1500; //cutoff
     if(doVariablePtMin && estMult < varPtCutoff) {
       minpt = 0.075;
-      if(estMult > 0) minpt += estMult * (thePtMin - 0.075)/varPtCutoff;
+      if(estMult > 0) minpt += estMult * (thePtMin - 0.075)/varPtCutoff; // lower ptMin linearly with pixel hit multiplicity
     }
 
     // tracking region selection

RecoHI/HiTracking/src/HIProtoTrackFilter.cc

@@ -100,13 +100,14 @@ void HIProtoTrackFilter::update(edm::Event& ev)
   edmNew::copyDetSetRange(*recHitColl,theChosenHits,acc.pixelBarrelLayer(1)); 	 
   float estMult = theChosenHits.size();
 
-  float varPtCutoff = 2000; //cutoff
-
   theVariablePtMin=thePtMin;
 
+  // parameterize ptMin such that a roughly constant number of selected prototracks passed are to vertexing
+  float varPtCutoff = 1500; //cutoff for variable ptMin
   if(estMult < varPtCutoff) {
     theVariablePtMin = 0.075;
-    if(estMult > 0) theVariablePtMin += estMult * (thePtMin - 0.075)/varPtCutoff;
+    if(estMult > 0) theVariablePtMin = (13. - (varPtCutoff/estMult) )/12.; 
+    if(theVariablePtMin<0.075) theVariablePtMin = 0.075; // don't lower the cut past 75 MeV
   }
 
   LogTrace("heavyIonHLTVertexing")<<"   [HIProtoTrackFilter: theVariablePtMin: " << theVariablePtMin << "]";