Restore option to generate weighted events in AliGenPythiaPlus and ad…

…d setting for AliPythia8
alisw · Apr 7, 2021 · a048450 · a048450
1 parent ee1868f
commit a048450
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Showing 5 changed files with 21 additions and 1 deletion.
diff --git a/PYTHIA6/AliPythia6/AliGenPythiaPlus.cxx b/PYTHIA6/AliPythia6/AliGenPythiaPlus.cxx
@@ -56,6 +56,7 @@ AliGenPythiaPlus::AliGenPythiaPlus():
     fNev(0),
     fFlavorSelect(0),
     fXsection(0.),
+    fWeightPower(0.),
     fPtHardMin(0.),
     fPtHardMax(1.e4),
     fYHardMin(-1.e10),
@@ -172,6 +173,7 @@ AliGenPythiaPlus::AliGenPythiaPlus(AliPythiaBase* pythia)
      fNev(0),
      fFlavorSelect(0),
      fXsection(0.),
+     fWeightPower(0.),
      fPtHardMin(0.),
      fPtHardMax(1.e4),
      fYHardMin(-1.e10),
@@ -369,7 +371,8 @@ void AliGenPythiaPlus::Init()
 //
     fParentWeight=1./Float_t(fNpart);
 //
-
+    if (fWeightPower != 0)
+      fPythia->SetWeightPower(fWeightPower);
 
     fPythia->SetPtHardRange(fPtHardMin, fPtHardMax);
     fPythia->SetYHardRange(fYHardMin, fYHardMax);

diff --git a/PYTHIA6/AliPythia6/AliGenPythiaPlus.h b/PYTHIA6/AliPythia6/AliGenPythiaPlus.h
@@ -50,6 +50,8 @@ class AliGenPythiaPlus : public AliGenMC
     virtual void    SetProcess(Process_t proc = kPyCharm) {fProcess = proc;}
     // Select structure function
     virtual void    SetStrucFunc(StrucFunc_t func =  kCTEQ5L) {fStrucFunc = func;}
+    // Rewieght pt, hard spectrum with pT/p0^n, set power n
+    virtual void    SetWeightPower(Float_t power = 0.) { fWeightPower = power; }
     // Select pt of hard scattering 
     virtual void    SetPtHard(Float_t ptmin = 0, Float_t ptmax = 1.e10)
 	{fPtHardMin = ptmin; fPtHardMax = ptmax; }
@@ -290,6 +292,7 @@ class AliGenPythiaPlus : public AliGenMC
     Int_t       fNev;               //Number of events 
     Int_t       fFlavorSelect;      //Heavy Flavor Selection
     Float_t     fXsection;          //Cross-section
+    Float_t     fWeightPower;       //power for cross section weights; 0 means no reweighting
     Float_t     fPtHardMin;         //lower pT-hard cut 
     Float_t     fPtHardMax;         //higher pT-hard cut
     Float_t     fYHardMin;          //lower  y-hard cut 

diff --git a/PYTHIA6/AliPythia6/AliPythiaBase.h b/PYTHIA6/AliPythia6/AliPythiaBase.h
@@ -39,6 +39,11 @@ class AliPythiaBase : public AliRndm
     virtual Int_t GetParticles(TClonesArray */*particles*/){return -1;}
     virtual void  PrintStatistics() {;}
     virtual void  EventListing() {;}
+    /**
+     * @brief Use weighted cross sections
+     * @param pow Weight power
+     */
+    virtual void SetWeightPower(Double_t pow) {;}
     // Treat protons as inside nuclei
     virtual void  SetNuclei(Int_t /*a1*/, Int_t /*a2*/) {;}
     // Print particle properties

diff --git a/PYTHIA8/AliPythia8/AliPythia8.cxx b/PYTHIA8/AliPythia8/AliPythia8.cxx
@@ -771,6 +771,10 @@ void AliPythia8::SetYHardRange(Float_t /*ymin*/, Float_t /*ymax*/)
 
 }
 
+void AliPythia8::SetWeightPower(Double_t pow){
+    ReadString("PhaseSpace:bias2Selection = on");
+    ReadString(Form("PhaseSpace:bias2SelectionPow = %13.3f", pow));
+}
 
 void AliPythia8::SetFragmentation(Int_t flag)
 {

diff --git a/PYTHIA8/AliPythia8/AliPythia8.h b/PYTHIA8/AliPythia8/AliPythia8.h
@@ -37,6 +37,11 @@ class AliPythia8 :public AliTPythia8, public AliPythiaBase
     virtual Int_t GetParticles(TClonesArray *particles) {return ImportParticles(particles, "All");}
     // Treat protons as inside nuclei
     virtual void  SetNuclei(Int_t a1, Int_t a2);
+    /**
+     * @brief Use weighted cross sections
+     * @param pow Weight power
+     */
+    virtual void SetWeightPower(Double_t pow);
     // Print particle properties
     virtual void PrintParticles();
     // Reset the decay table