ana_Lambda.C

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void propagate(TLorentzVector &l, TVector3 &p, float charge, TH2F* hpro=0)
{
  double x0=p.X()/100;
  double y0=p.Y()/100;
  double z0=p.Z()/100;

  double px0=l.Px();
  double py0=l.Py();
  double pz0=l.Pz();

  double B=2;

  double pt=sqrt(px0*px0+py0*py0);
  double lambda=pz0/pt;
  double s_t=z0/lambda;
  double a=-0.2998*B*charge/3;
  double rho=a/pt;

  //cout <<hpro<<endl;

  if (hpro)
  {
    int steps=100;
    double dz=z0/steps;
    for (int i=0;i<steps;i++)
    {
      if (i==90) i=99;
      double s_tt=(i+1)*dz/lambda;
      double cosrst=cos(rho*s_tt);
      double sinrst=sin(rho*s_tt);

      double px = px0*cosrst + py0*sinrst;
      double py = py0*cosrst - px0*sinrst;
      //double pz = pz0;

      double xt=x0 - px/a*sinrst + py/a*(1-cosrst);
      double yt=y0 - py/a*sinrst - px/a*(1-cosrst);
      //double z=z0 - lambda*s_tt;

       hpro->Fill(xt,yt);
    }
  }

  //cout <<"lam="<<atan(1/lambda)/3.1416*180<<" "<<rho<<" "<<s_t<<endl;

  double cosrs=cos(rho*s_t);
  double sinrs=sin(rho*s_t);

  double px = px0*cosrs + py0*sinrs;
  double py = py0*cosrs - px0*sinrs;
  double pz = pz0;

  double x=x0 - px/a*sinrs + py/a*(1-cosrs);
  double y=y0 - py/a*sinrs - px/a*(1-cosrs);
  double z=z0 - lambda*s_t;

  l.SetX(px);
  l.SetY(py);
  l.SetZ(pz);

  p.SetX(x*100);
  p.SetY(y*100);
  p.SetZ(z*100);
}

int ana_Lambda(TString fname="tmp.root",int num=0)
{
    TStopwatch timer;
    timer.Start();

    gROOT->LoadMacro("$VMCWORKDIR/gconfig/basiclibs.C");
    basiclibs();

    // **** the library is needed in order to use the TCandidate and TCandList etc
    gSystem->Load("libRho");

    TCanvas *c1=new TCanvas("c1","c1",600,600);

    // **** access the datastructure holding the particle lists
    //
    TFile* f = new TFile(fname.Data());
    TTree *t=f->Get("pndsim") ;

    // **** for every event, a TCLonesArray with the candidates is stored in pndsim
    //
    TClonesArray *fChrgCands=new TClonesArray("TCandidate");
    //TClonesArray *fNeutCands=new TClonesArray("TCandidate");
    //TClonesArray *fMcCands=new TClonesArray("TCandidate");

    t->SetBranchAddress("PndChargedCandidates",&fChrgCands);
    //t->SetBranchAddress("PndNeutralCandidates",&fNeutCands);
    //t->SetBranchAddress("PndMcTracks",&fMcCands);

    TCandidate *tc;

    // **** create and setup some histos for QA plots
    //
    TH1F *ppimass = new TH1F("ppimass","p pi cands",100,1.115-0.2,1.115+0.2);

    ppimass->SetMinimum(0);

    if (num==0) num= t->GetEntriesFast();
    cout <<"\n####### Processing "<<num <<" events...\n"<<endl;

    // **** create all the particle lists we'll need for rebuilding the decay tree
    //
    TCandList mcCands;

    TCandList allCands,chargedCands, minusCands, plusCands, pplusCands, pminusCands, piplusCands, piminusCands;

    TCandList ppiCands;

    // **** create and configure the selectors/filters we'd like to use later
    //
    TPidChargedSelector *chargedSel = new TPidChargedSelector;
    TPidNeutralSelector *neutralSel = new TPidNeutralSelector;

    TPidPlusSelector    *plusSel    = new TPidPlusSelector;
    TPidMinusSelector   *minusSel   = new TPidMinusSelector;

    // **** mass selectors for the resonances/composites
    //
    TPidSimplePionSelector *piSel    = new TPidSimplePionSelector();
    piSel->SetCriterion("veryLoose");
    TPidSimpleProtonSelector *pSel    = new TPidSimpleProtonSelector();
    pSel->SetCriterion("veryLoose");

    int i1,i2;

    // **** loop over all _events_
    //
    for (Int_t j=0; j< num;j++)
    {
       if ((j%100)==0) cout <<"evt "<<j<<endl;

        t->GetEntry(j);
        TFactory::Instance()->Reset();

        chargedCands.Cleanup();

        // **** loop over all Candidates and add them to the list allCands
        //

        for (i1=0; i1<fChrgCands->GetEntriesFast(); i1++){
            tc = (TCandidate *)fChrgCands->At(i1);

            TLorentzVector l=tc->P4();
            TVector3 p=tc->Pos();

            propagate(l,p,tc->GetCharge());
            tc->SetP4(l);
            tc->SetPos(p);

            chargedCands.Add(*tc);

        }

        plusCands.Select(chargedCands, plusSel);
        minusCands.Select(chargedCands, minusSel);

        pplusCands.Select(plusCands,pSel);
        pminusCands.Select(minusCands,pSel);

        piplusCands.Select(plusCands,piSel);
        piminusCands.Select(minusCands,piSel);

        cout <<"chrg:"<<chargedCands.GetLength()<<" ";
        cout <<"plus:"<<plusCands.GetLength()<<" ";
        cout <<"minus:"<<minusCands.GetLength()<<" ";
        cout <<"p+:"<<pplusCands.GetLength()<<" ";
        cout <<"p-:"<<pminusCands.GetLength()<<" ";
        cout <<"pi+:"<<piplusCands.GetLength()<<" ";
        cout <<"pi-:"<<piminusCands.GetLength()<<endl;

        // **** select all the basic list
        //

        //cout <<"c:"<<chargedCands.GetLength()<<" n:"<<neutralCands.GetLength()<<endl;


        ppiCands.Combine(pplusCands,piminusCands);
        ppiCands.CombineAndAppend(pminusCands,piplusCands);

        TCandListIterator iterP(ppiCands);
        while (tc=iterP.Next()) ppimass->Fill(tc->M());
    }
    // **** plot all that stuff
    //
    c1->cd(1);
    ppimass->Draw();


    timer.Stop();
    Double_t rtime = timer.RealTime();
    Double_t ctime = timer.CpuTime();

    printf("RealTime=%f seconds, CpuTime=%f seconds\n",rtime,ctime);

  return 0;
}

/*void printTree(TCandidate *tc, int level=0)
{
  int i=0;
  int nd=tc->NDaughters();
  if (nd==0) return;
  cout <<tc->Uid()<<"("<<level<<") -> ";
  for (i=0;i<nd;i++) cout<<tc->Daughter(i)->Uid()<<"  ";
  cout <<endl;
  for (i=0;i<nd;i++) printTree(tc->Daughter(i),level+1);
  if (level==0) cout <<endl;
}
*/