Generator for HF enhanced PbPb MC for dielectron analysis

MC/config/PWGEM/external/generator/Generator_pythia8_HFLepton_pp.C

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+#include "Pythia8/Pythia.h"
+#include "Pythia8/HeavyIons.h"
+#include "FairGenerator.h"
+#include "FairPrimaryGenerator.h"
+#include "Generators/GeneratorPythia8.h"
+#include "TRandom3.h"
+#include "TParticlePDG.h"
+#include "TDatabasePDG.h"
+
+#include <map>
+#include <unordered_set>
+
+using namespace Pythia8;
+
+class GeneratorPythia8HFLeptonpp : public o2::eventgen::GeneratorPythia8
+{
+public:
+  /// default constructor
+  GeneratorPythia8HFLeptonpp() = default;
+
+  /// constructor
+  GeneratorPythia8HFLeptonpp(TString configsignal, int quarkPdg = 4, int lInputExternalID = 0)
+  {
+
+    lGeneratedEvents = 0;
+    lExternalID = lInputExternalID;
+    mQuarkPdg = quarkPdg;
+
+    auto seed = (gRandom->TRandom::GetSeed() % 900000000);
+
+    int offset = (int)(gRandom->Uniform(1)); // create offset to mitigate edge effects due to small number of events per job
+    lGeneratedEvents += offset;
+
+    cout << "Initalizing PYTHIA object used to generate signal events..." << endl;
+    TString pathconfigSignal = gSystem->ExpandPathName(configsignal.Data());
+    pythiaObjectSignal.readFile(pathconfigSignal.Data());
+    pythiaObjectSignal.readString("Random:setSeed on");
+    pythiaObjectSignal.readString("Random:seed " + std::to_string(seed));
+    pythiaObjectSignal.readString("Beams:eCM = 5360.0");
+    pythiaObjectSignal.init();
+    cout << "Initalization of signal event is complete" << endl;
+
+    // flag the generators using type
+    // addCocktailConstituent(type, "interesting");
+    // addCocktailConstitent(0, "minbias");
+    // Add Sub generators
+    addSubGenerator(1, "charm lepton");
+    addSubGenerator(2, "beauty forced decay");
+    addSubGenerator(3, "beauty no foced decay");
+  }
+
+  ///  Destructor
+  ~GeneratorPythia8HFLeptonpp() = default;
+
+  void addTriggerOnDaughter(int nb, int pdg)
+  {
+    mNbDaughter = nb;
+    mPdgDaughter = pdg;
+  };
+  void setQuarkRapidity(float yMin, float yMax)
+  {
+    mQuarkRapidityMin = yMin;
+    mQuarkRapidityMax = yMax;
+  };
+  void setDaughterRapidity(float yMin, float yMax)
+  {
+    mDaughterRapidityMin = yMin;
+    mDaughterRapidityMax = yMax;
+  };
+
+protected:
+  //__________________________________________________________________
+  Bool_t generateEvent() override
+  {
+    /// reset event
+    mPythia.event.reset();
+
+    // Generate event of interest
+    Bool_t lGenerationOK = kFALSE;
+    while (!lGenerationOK) {
+      if (pythiaObjectSignal.next()) {
+        lGenerationOK = selectEvent(pythiaObjectSignal.event);
+      }
+    }
+    mPythia.event = pythiaObjectSignal.event;
+    notifySubGenerator(lExternalID);
+
+    lGeneratedEvents++;
+    // mPythia.next();
+
+    return true;
+  }
+
+  bool selectEvent(const Pythia8::Event& event)
+  {
+    bool isGoodAtPartonLevel = false, isGoodAtDaughterLevel = (mPdgDaughter != 0) ? false : true;
+    int nbDaughter = 0;
+    for (auto iPart{0}; iPart < event.size(); ++iPart) {
+      // search for Q-Qbar mother with at least one Q in rapidity window
+      if (!isGoodAtPartonLevel) {
+        auto daughterList = event[iPart].daughterList();
+        bool hasQ = false, hasQbar = false, atSelectedY = false;
+        for (auto iDau : daughterList) {
+          if (event[iDau].id() == mQuarkPdg) {
+            hasQ = true;
+          }
+          if (event[iDau].id() == -mQuarkPdg) {
+            hasQbar = true;
+          }
+          if ((std::abs(event[iDau].id()) == mQuarkPdg) && (event[iDau].y() > mQuarkRapidityMin) && (event[iDau].y() < mQuarkRapidityMax))
+            atSelectedY = true;
+        }
+        if (hasQ && hasQbar && atSelectedY) {
+          isGoodAtPartonLevel = true;
+        }
+      }
+      // search for mNbDaughter daughters of type mPdgDaughter in rapidity window
+      if (!isGoodAtDaughterLevel) {
+        int id = std::abs(event[iPart].id());
+        float rap = event[iPart].y();
+        if (id == mPdgDaughter) {
+          int motherindexa = event[iPart].mother1();
+          if (motherindexa > 0) {
+            int idmother = std::abs(event[motherindexa].id());
+            if (int(std::abs(idmother) / 100.) == 4 || int(std::abs(idmother) / 1000.) == 4 || int(std::abs(idmother) / 100.) == 5 || int(std::abs(idmother) / 1000.) == 5) {
+              if (rap > mDaughterRapidityMin && rap < mDaughterRapidityMax) {
+                nbDaughter++;
+                if (nbDaughter >= mNbDaughter) isGoodAtDaughterLevel = true;
+              }
+            }
+          }
+        }
+      }
+      // we send the trigger
+      if (isGoodAtPartonLevel && isGoodAtDaughterLevel) {
+        return true;
+      }
+    }
+    return false;
+  };
+
+private:
+  // Interface to override import particles
+  Pythia8::Event mOutputEvent;
+
+  // Properties of selection
+  int mQuarkPdg;
+  float mQuarkRapidityMin;
+  float mQuarkRapidityMax;
+  int mPdgDaughter;
+  int mNbDaughter;
+  float mDaughterRapidityMin;
+  float mDaughterRapidityMax;
+
+  Long64_t lGeneratedEvents;
+  // ID for different generators
+  int lExternalID;
+
+  // Base event generators
+  Pythia8::Pythia pythiaObjectSignal;      ///Signal collision generator
+};
+
+// Predefined generators:
+
+// Charm-enriched forced decay
+FairGenerator* GeneratorPythia8CharmLepton(int inputExternalID, int pdgLepton, float yMinQ = -1.5, float yMaxQ = 1.5, float yMinL = -1, float yMaxL = 1)
+{
+  auto myGen = new GeneratorPythia8HFLeptonpp("${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGEM/pythia8/generator/pythia8_pp_cr2_forceddecayscharm.cfg", 4, inputExternalID);
+  auto seed = (gRandom->TRandom::GetSeed() % 900000000);
+  myGen->readString("Random:setSeed on");
+  myGen->readString("Random:seed " + std::to_string(seed));
+  myGen->setQuarkRapidity(yMinQ, yMaxQ);
+  myGen->addTriggerOnDaughter(2, pdgLepton);
+  myGen->setDaughterRapidity(yMinL, yMaxL);
+  return myGen;
+}
+
+// Beauty-enriched forced decay
+FairGenerator* GeneratorPythia8BeautyForcedDecays(int inputExternalID, int pdgLepton, float yMinQ = -1.5, float yMaxQ = 1.5, float yMinL = -1, float yMaxL = 1)
+{
+  auto myGen = new GeneratorPythia8HFLeptonpp("${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGEM/pythia8/generator/pythia8_bbbar_forceddecayscharmbeauty.cfg", 5, inputExternalID);
+  auto seed = (gRandom->TRandom::GetSeed() % 900000000);
+  myGen->readString("Random:setSeed on");
+  myGen->readString("Random:seed " + std::to_string(seed));
+  myGen->setQuarkRapidity(yMinQ, yMaxQ);
+  myGen->addTriggerOnDaughter(2, pdgLepton);
+  myGen->setDaughterRapidity(yMinL, yMaxL);
+  return myGen;
+}
+
+// Beauty-enriched no forced decay
+FairGenerator* GeneratorPythia8BeautyNoForcedDecays(int inputExternalID, int pdgLepton, float yMinQ = -1.5, float yMaxQ = 1.5, float yMinL = -1, float yMaxL = 1)
+{
+  auto myGen = new GeneratorPythia8HFLeptonpp("${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGEM/pythia8/generator/pythia8_bbbar.cfg", 5, inputExternalID);
+  auto seed = (gRandom->TRandom::GetSeed() % 900000000);
+  myGen->readString("Random:setSeed on");
+  myGen->readString("Random:seed " + std::to_string(seed));
+  myGen->setQuarkRapidity(yMinQ, yMaxQ);
+  myGen->addTriggerOnDaughter(2, pdgLepton);
+  myGen->setDaughterRapidity(yMinL, yMaxL);
+  return myGen;
+}