analyze_pp_delta_dalitz.C

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{
    TFile *f = (TFile*)gROOT->GetListOfFiles()->FindObject("pp_delta_dalitz.root");
    if (!f) f = new TFile("pp_delta_dalitz.root");
    TTree *Reaction = (TTree*)gDirectory->Get("data");
    TClonesArray *evt  = new TClonesArray("PParticle", 7);
    TClonesArray *evt2 = new TClonesArray("PParticle", 3);
    Reaction->SetBranchAddress("Particles", &evt);
    Reaction->SetBranchAddress("Accepted",  &evt2);
    
    PParticle *par[7];
    PParticle *par2[3];
    
    const double r2d = 180./3.14159265358979323846; 
    TVector3 v1, v2;
    
    TH1F *hf1 = new TH1F("hf1", "#Delta mass", 200, 1.05, 1.4);
    TH1F *hf2 = new TH1F("hf2", "#Delta lab prod angle (deg)", 200, 0., 45.);
    TH1F *hf3 = new TH1F("hf3", "Dilepton mass", 200, 0., .37);
    TH1F *hf4 = new TH1F("hf4", "accepted e^{+} and e^{-} scattering angle (deg)", 200, 10., 90.);
    TH1F *hf5 = new TH1F("hf5", "accepted dilepton rapidity", 200, 0, 2);
    TH1F *hf6 = new TH1F("hf6", "accepted e^{+}e^{-} opening angle", 200, 0., 160.);
 
    c1 = new TCanvas("c1", "p + p -> p + Delta -> p + p + gamma* -> p + p + e- + e+", 200, 10, 900, 900);
    c1->Divide(3, 2);
    c1->SetFillColor(10);
    c1_3->SetLogy();
    c1_6->SetLogy();
    hf1->SetFillColor(10);
    hf2->SetFillColor(10);
    hf3->SetFillColor(10);
    hf4->SetFillColor(10);
    hf5->SetFillColor(10);
    hf6->SetFillColor(10);
 
    Int_t nentries = Reaction->GetEntries();
    for (Int_t i=0; i<nentries; i++) {
    Reaction->GetEntry(i);
    par[2] = (PParticle*)evt->At(2);
    par[4] = (PParticle*)evt->At(4);
    par[5] = (PParticle*)evt->At(5);
    par[6] = (PParticle*)evt->At(6);
    hf1->Fill(par[2]->M());
    hf2->Fill(r2d*(par[2]->Theta()));
    hf3->Fill(par[4]->M());
 
 
    par2[0] = (PParticle*)evt2->At(0);
    par2[1] = (PParticle*)evt2->At(1);
    par2[2] = (PParticle*)evt2->At(2);
    if ( par2[0] ) {
        hf4->Fill(r2d*(par2[1]->Theta()));
        hf4->Fill(r2d*(par2[2]->Theta()));
        hf5->Fill(par2[0]->Rapidity());
        v1 = par2[1]->Vect();
        v2 = par2[2]->Vect();
        hf6->Fill(r2d*(acos(v1.Dot(v2)/(v1.Mag()*v2.Mag()))));
    }
    }
    c1_1->cd();
    c1_1->SetFillColor(10);
    hf1->Draw();
    c1_2->cd();
    c1_2->SetFillColor(10);
    hf2->Draw();
    c1_3->cd();
    c1_3->SetFillColor(10);
    hf3->Draw();
    c1_4->cd();
    c1_4->SetFillColor(10);
    hf4->Draw();
    c1_5->cd();
    c1_5->SetFillColor(10);
    hf5->Draw();
    c1_6->cd();
    c1_6->SetFillColor(10);
    hf6->Draw();
}