Add J/psi resolution; re-write RC with Dummy instead of rc tracks

benchmarks/dvmp/analysis/dvmp.h

@@ -17,13 +17,6 @@
 // promoted to the top-level util library
 namespace util {
 
-  // Calculate the 4-vector sum of a given pair of particles
-  inline ROOT::Math::PxPyPzMVector
-  get_sum(const std::pair<ROOT::Math::PxPyPzMVector, ROOT::Math::PxPyPzMVector>& particle_pair)
-  {
-    return (particle_pair.first + particle_pair.second);
-  }
-
   //========================================================================================================
   // for structure functions
 
@@ -36,26 +29,29 @@ namespace util {
   {
     ROOT::Math::PxPyPzMVector q(parts[0] - parts[2]);
     ROOT::Math::PxPyPzMVector P(parts[3]);
-    ROOT::Math::PxPyPzMVector Delta(parts[6] - parts[3]);
+    //ROOT::Math::PxPyPzMVector Delta(parts[6] - parts[3]);//exact jpsi
+    ROOT::Math::PxPyPzMVector Delta(parts[0] - parts[2] - parts[7] - parts[8]);//jpsi->l l' gamma, ignore gamma
 
     double    nu         = q.Dot(P) / P.mass();
     double    Q2         = -q.Dot(q);
     double t = Delta.Dot(Delta);
-    inv_quant quantities = {nu, Q2, Q2 / 2. / P.mass() / nu, t};
+    inv_quant quantities = {nu, Q2, Q2/2./P.mass()/nu, t};
     return quantities;
   }
   
-  //for tracking
-  inline inv_quant calc_inv_quant_rec(const std::vector<ROOT::Math::PxPyPzMVector>& parts, const double pdg_mass){
+ //for Dummy rc
+  inline inv_quant calc_inv_quant_rec(const std::vector<ROOT::Math::PxPyPzMVector>& parts, const double pdg_mass, const double daughter_mass){
     int first = -1;
     int second = -1;
     double best_mass = -1;
-
+    
     // go through all particle combinatorics, calculate the invariant mass
     // for each combination, and remember which combination is the closest
     // to the desired pdg_mass
     for (int i = 0; i < parts.size(); ++i) {
+      if( fabs(parts[i].mass() - daughter_mass)/daughter_mass > 0.001) continue;
       for (int j = i + 1; j < parts.size(); ++j) {
+        if( fabs(parts[j].mass() - daughter_mass)/daughter_mass > 0.001) continue;
         const double new_mass{(parts[i] + parts[j]).mass()};
         if (fabs(new_mass - pdg_mass) < fabs(best_mass - pdg_mass)) {
           first = i;
@@ -64,10 +60,14 @@ namespace util {
         }
       }
     }
-    if (first < 0 || parts.size() < 3 ){
-      inv_quant quantities = {-999., -999., -999., -999.};
+    
+    
+    if (first < 0 || parts.size() < 3 ){      //fewer than 3 candidates 
+      inv_quant quantities = {-99999., -99999., -99999., -99999.};
       return quantities;
     }
+    
+    //construct the beam kinematics
     ROOT::Math::PxPyPzMVector pair_4p(parts[first] + parts[second]);
     ROOT::Math::PxPyPzMVector e1, P;
     double e1_Energy = sqrt(10.*10. + get_pdg_mass("electron")*get_pdg_mass("electron"));
@@ -75,19 +75,21 @@ namespace util {
     e1.SetPxPyPzE(0., 0., -10., e1_Energy);
     P.SetPxPyPzE(0., 0., 100., P_Energy);
     int scatteredIdx = -1;
-    float dp = 10.;
+    
+    //float dp = 10.;
     for(int i = 0 ; i < parts.size(); i++){
-      if(i==first || i==second) continue;
-      ROOT::Math::PxPyPzMVector k_prime(parts[i]);
-      float ptmp = sqrt(parts[i].px()*parts[i].px() + parts[i].py()*parts[i].py() + parts[i].pz()*parts[i].pz());
-      if( (k_prime.px()) * (pair_4p.px()) + (k_prime.py()) * (pair_4p.py()) + (k_prime.pz()) * (pair_4p.pz()) > 0. || ptmp >= 10.) continue; //angle between jpsi and scattered electron < pi/2, 3-momentum mag < 10.
-      if(dp > 10.- ptmp){     //if there are more than one candidate of scattered electron, choose the one with highest 3-momentum mag
+      if(i==first || i==second) continue;   //skip the paired leptons
+      if( fabs(parts[i].mass() - get_pdg_mass("electron"))/get_pdg_mass("electron") > 0.001) continue;
+      //ROOT::Math::PxPyPzMVector k_prime(parts[i]);  //scattered
+      //float ptmp = sqrt(parts[i].px()*parts[i].px() + parts[i].py()*parts[i].py() + parts[i].pz()*parts[i].pz());
+      //if( (k_prime.px()) * (pair_4p.px()) + (k_prime.py()) * (pair_4p.py()) + (k_prime.pz()) * (pair_4p.pz()) > 0. || ptmp >= 10.) continue; //angle between jpsi and scattered electron < pi/2, 3-momentum mag < 10. 
+      //if(dp > 10.- ptmp){     //if there are more than one candidate of scattered electron, choose the one with highest 3-momentum mag
         scatteredIdx = i;
-        dp = 10. - ptmp;
-      }
+      //  dp = 10. - ptmp;
+      //}
     }
     if(scatteredIdx ==-1){
-      inv_quant quantities = {-999., -999., -999., -999.};
+      inv_quant quantities = {-99999., -99999., -99999., -99999.};
       return quantities;
     }
     ROOT::Math::PxPyPzMVector q(e1 - parts[scatteredIdx]);
@@ -97,15 +99,9 @@ namespace util {
     double Q2 = - q.Dot(q);  
     double t = Delta.Dot(Delta);
     inv_quant quantities = {nu, Q2, Q2/2./P.mass()/nu, t};
-    //inv_quant quantities = {-999., -999., -999., -999.};
     return quantities;
   }
-
-  
-  
   
-  
-
   inline double get_nu(inv_quant quantities) { return quantities.nu / 1000.; }
   inline double get_Q2(inv_quant quantities) { return quantities.Q2; }
   inline double get_x(inv_quant quantities) { return quantities.x; }