LF: add multi-strange enriched generator (AliceO2Group#1722)

MC/config/PWGLF/ini/GeneratorLF_Strangeness_PbPb5360_injection.ini

@@ -0,0 +1,6 @@
+[GeneratorExternal]
+fileName=${O2DPG_ROOT}/MC/config/PWGLF/pythia8/generator_pythia8_extraStrangeness.C
+funcName=generator_extraStrangeness()
+
+[GeneratorPythia8]
+config=${O2DPG_ROOT}/MC/config/common/pythia8/generator/pythia8_hi.cfg

MC/config/PWGLF/ini/tests/GeneratorLF_Strangeness_PbPb5360_injection.C

@@ -0,0 +1,28 @@
+int External()
+{
+    std::string path{"o2sim_Kine.root"};
+
+    TFile file(path.c_str(), "READ");
+    if (file.IsZombie())
+    {
+        std::cerr << "Cannot open ROOT file " << path << "\n";
+        return 1;
+    }
+
+    auto tree = (TTree *)file.Get("o2sim");
+    if (!tree)
+    {
+        std::cerr << "Cannot find tree o2sim in file " << path << "\n";
+        return 1;
+    }
+    std::vector<o2::MCTrack> *tracks{};
+    tree->SetBranchAddress("MCTrack", &tracks);
+
+    auto nEvents = tree->GetEntries();
+    if (nEvents < 1)
+    {
+        std::cerr << "No events actually generated: not OK!";
+        return 1;
+    }
+    return 0;
+}

MC/config/PWGLF/pythia8/generator_pythia8_extraStrangeness.C

@@ -0,0 +1,243 @@
+
+#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>
+
+class GeneratorPythia8ExtraStrangeness : public o2::eventgen::GeneratorPythia8
+{
+public:
+  /// Constructor
+  GeneratorPythia8ExtraStrangeness() {
+    genMinPt=0.0;
+    genMaxPt=20.0;
+    genminY=-1.5;
+    genmaxY=1.5;
+    genminEta=-1.5;
+    genmaxEta=1.5;
+
+    pdg=0;
+    E=0;
+    px=0;
+    py=0;
+    pz=0;
+    p=0;
+    y=0;
+    eta=0;
+    xProd=0;
+    yProd=0;
+    zProd=0;
+    xProd=0.; yProd=0.; zProd=0.;
+
+    fLVHelper = std::make_unique<TLorentzVector>();
+  }
+
+  Double_t y2eta(Double_t pt, Double_t mass, Double_t y){
+    Double_t mt = TMath::Sqrt(mass * mass + pt * pt);
+    return TMath::ASinH(mt / pt * TMath::SinH(y));
+  }
+
+  /// set 4-momentum
+  void set4momentum(double input_px, double input_py, double input_pz){
+    px = input_px;
+    py = input_py;
+    pz = input_pz;
+    E  = sqrt( m*m+px*px+py*py+pz*pz );
+    fourMomentum.px(px);
+    fourMomentum.py(py);
+    fourMomentum.pz(pz);
+    fourMomentum.e(E);
+    p   = sqrt( px*px+py*py+pz*pz );
+    y   = 0.5*log( (E+pz)/(E-pz) );
+    eta = 0.5*log( (p+pz)/(p-pz) );
+  }
+
+  //__________________________________________________________________
+  Pythia8::Particle createParticle(){
+    //std::cout << "createParticle() mass " << m << " pdgCode " << pdg << std::endl;
+    Pythia8::Particle myparticle;
+    myparticle.id(pdg);
+    myparticle.status(11);
+    myparticle.px(px);
+    myparticle.py(py);
+    myparticle.pz(pz);
+    myparticle.e(E);
+    myparticle.m(m);
+    myparticle.xProd(xProd);
+    myparticle.yProd(yProd);
+    myparticle.zProd(zProd);
+
+    return myparticle;
+  }
+
+  //_________________________________________________________________________________
+  /// generate uniform eta and uniform momentum
+  void genSpectraMomentumEtaXi(double minP, double maxP, double minY, double maxY){
+    // random generator
+    std::unique_ptr<TRandom3> ranGenerator { new TRandom3() };
+    ranGenerator->SetSeed(0);
+
+    // generate transverse momentum
+    const double gen_pT = ranGenerator->Uniform(0,5);
+
+    //Actually could be something else without loss of generality but okay
+    const double gen_phi = ranGenerator->Uniform(0,2*TMath::Pi());
+
+    // sample flat in rapidity, calculate eta
+    Double_t gen_Y=10, gen_eta=10;
+
+    while( gen_eta>genmaxEta || gen_eta<genminEta ){
+      gen_Y = ranGenerator->Uniform(minY,maxY);
+      //(Double_t pt, Double_t mass, Double_t y)
+      gen_eta = y2eta(gen_pT, m, gen_Y);
+    }
+
+    fLVHelper->SetPtEtaPhiM(gen_pT, gen_eta, gen_phi, m);
+    set4momentum(fLVHelper->Px(),fLVHelper->Py(),fLVHelper->Pz());
+  }
+
+  //_________________________________________________________________________________
+  /// generate uniform eta and uniform momentum
+  void genSpectraMomentumEtaOm(double minP, double maxP, double minY, double maxY){
+    // random generator
+    std::unique_ptr<TRandom3> ranGenerator { new TRandom3() };
+    ranGenerator->SetSeed(0);
+
+    // generate transverse momentum
+    const double gen_pT = ranGenerator->Uniform(0,5);
+
+    //Actually could be something else without loss of generality but okay
+    const double gen_phi = ranGenerator->Uniform(0,2*TMath::Pi());
+
+    // sample flat in rapidity, calculate eta
+    Double_t gen_Y=10, gen_eta=10;
+
+    while( gen_eta>genmaxEta || gen_eta<genminEta ){
+      gen_Y = ranGenerator->Uniform(minY,maxY);
+      //(Double_t pt, Double_t mass, Double_t y)
+      gen_eta = y2eta(gen_pT, m, gen_Y);
+    }
+
+    fLVHelper->SetPtEtaPhiM(gen_pT, gen_eta, gen_phi, m);
+    set4momentum(fLVHelper->Px(),fLVHelper->Py(),fLVHelper->Pz());
+  }
+
+  //__________________________________________________________________
+  Bool_t generateEvent() override {
+
+    // Generate PYTHIA event
+    Bool_t lPythiaOK = kFALSE;
+    while (!lPythiaOK){
+      lPythiaOK = mPythia.next();
+      //if(TMath::Abs(mPythia.info.hiInfo->b()-8.5)>0.5) lPythiaOK = false; // select peripheral for flow
+    }
+
+    // characterise event
+    Long_t nParticles = mPythia.event.size();
+    Long_t nChargedParticlesAtMidRap = 0;
+    Long_t nPionsAtMidRap = 0;
+    for ( Long_t j=0; j < nParticles; j++ ) {
+      Int_t pypid = mPythia.event[j].id();
+      Float_t pyrap = mPythia.event[j].y();
+      Float_t pyeta = mPythia.event[j].eta();
+
+      // final only
+      if (!mPythia.event[j].isFinal()) continue;
+
+      if ( TMath::Abs(pyrap) < 0.5 && TMath::Abs(pypid)==211 ) nPionsAtMidRap++;
+      if ( TMath::Abs(pyeta) < 0.5 && TMath::Abs(mPythia.event[j].charge())>1e-5 ) nChargedParticlesAtMidRap++;
+    }
+
+    // now we have the multiplicity
+
+    //+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    // XI ABUNDANCE FIX
+//    FCN=0.35879 FROM MINOS     STATUS=SUCCESSFUL    126 CALLS         634 TOTAL
+//                        EDM=3.7456e-09    STRATEGY= 1      ERROR MATRIX ACCURATE
+//     EXT PARAMETER                                   STEP         FIRST
+//     NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE
+//      1  p0           4.74929e-03   3.29248e-04  -3.35914e-06   5.38225e+00
+//      2  p1          -4.08255e-03   8.62587e-04  -2.02577e-05   2.45132e+00
+//      3  p2           4.76660e+00   1.93593e+00   1.93593e+00   2.70369e-04
+//   Info in <TCanvas::MakeDefCanvas>:  created default TCanvas with name c1
+    //Adjust relative abundance of multi-strange particles by injecting some
+    Double_t lExpectedXiToPion = TMath::Max(4.74929e-03 - 4.08255e-03*TMath::Exp(-nChargedParticlesAtMidRap/4.76660e+00) - 0.00211334,0.);
+    Double_t lExpectedXi = 5.0*nPionsAtMidRap*lExpectedXiToPion; // extra rich, factor 5
+    Int_t lXiYield = gRandom->Poisson(3*lExpectedXi); //factor 3: fix the rapidity acceptance
+    m = 1.32171;
+    pdg = 3312;
+    cout<<"Adding extra xi: "<<lXiYield<<" (to reach average "<<Form("%.6f",lExpectedXi)<<" at this Nch = "<<nChargedParticlesAtMidRap<<", ratio: "<<Form("%.6f",lExpectedXiToPion)<<")"<<endl;
+    for(Int_t ii=0; ii<lXiYield; ii++){
+      pdg *= gRandom->Uniform()>0.5?+1:-1;
+      xProd=0.0;
+      yProd=0.0;
+      zProd=0.0;
+      genSpectraMomentumEtaXi(genMinPt,genMaxPt,genminY,genmaxY);
+      Pythia8::Particle lAddedParticle = createParticle();
+      mPythia.event.append(lAddedParticle);
+      //lAddedParticles++;
+    }
+    //+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+    //+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    // OMEGA ABUNDANCE FIX
+    //Adjust relative abundance of multi-strange particles by injecting some
+    Double_t lExpectedOmegaToPion = TMath::Max(8.55057e-04 - 7.38732e-04*TMath::Exp(-nChargedParticlesAtMidRap/2.40545e+01) - 6.56785e-05,0.);
+    Double_t lExpectedOmega = 5.0*nPionsAtMidRap*lExpectedOmegaToPion; // extra rich, factor 5
+    Int_t lOmegaYield = gRandom->Poisson(3*lExpectedOmega); //factor 3: fix the rapidity acceptance
+    m = 1.67245;
+    pdg = 3334;
+    cout<<"Adding extra omegas: "<<lOmegaYield<<" (to reach average "<<Form("%.6f",lExpectedOmega)<<" at this Nch = "<<nChargedParticlesAtMidRap<<", ratio: "<<Form("%.6f",lExpectedOmegaToPion)<<")"<<endl;
+    for(Int_t ii=0; ii<lOmegaYield; ii++){
+      pdg *= gRandom->Uniform()>0.5?+1:-1;
+      xProd=0.0;
+      yProd=0.0;
+      zProd=0.0;
+      genSpectraMomentumEtaOm(genMinPt,genMaxPt,genminY,genmaxY);
+      Pythia8::Particle lAddedParticle = createParticle();
+      mPythia.event.append(lAddedParticle);
+      //lAddedParticles++;
+    }
+    //+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+    return true;
+  }
+
+private:
+
+  double genMinPt;      /// minimum 3-momentum for generated particles
+  double genMaxPt;      /// maximum 3-momentum for generated particles
+  double genminY;    /// minimum pseudorapidity for generated particles
+  double genmaxY;    /// maximum pseudorapidity for generated particles
+  double genminEta;
+  double genmaxEta;
+
+  Pythia8::Vec4   fourMomentum;  /// four-momentum (px,py,pz,E)
+
+  double E;        /// energy: sqrt( m*m+px*px+py*py+pz*pz ) [GeV/c]
+  double m;        /// particle mass [GeV/c^2]
+  int    pdg;        /// particle pdg code
+  double px;        /// x-component momentum [GeV/c]
+  double py;        /// y-component momentum [GeV/c]
+  double pz;        /// z-component momentum [GeV/c]
+  double p;        /// momentum
+  double y;        /// rapidity
+  double eta;        /// pseudorapidity
+  double xProd;      /// x-coordinate position production vertex [cm]
+  double yProd;      /// y-coordinate position production vertex [cm]
+  double zProd;      /// z-coordinate position production vertex [cm]
+
+  std::unique_ptr<TLorentzVector> fLVHelper;
+};
+
+ FairGenerator *generator_extraStrangeness()
+ {
+   return new GeneratorPythia8ExtraStrangeness();
+ }