eta_disto.C

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//TITLE The pp->ppeta reaction with N* contribution from DISTO
//This macro generates 4 different models for this reaction
 
{
    Bool_t eta_helicity = kTRUE;
    Bool_t pp_model = kTRUE;
    
    Int_t ascii = 1;
    
    // beam
    
    PParticle p1("p", 2.2);
    //PParticle p1("p",2.85);
    PParticle p2("p");
 
    PParticle q = p1 + p2;
 
 
    PDecayChannel *c = new PDecayChannel;
    PDecayManager *pdm = new PDecayManager;
    pdm->SetVerbose(1);
    PDistributionManager *dim = pdm->GetDistributionManager();
 
    //primary meson production NONRESONANT
    c->AddChannel(0.42, "p", "p", "eta");
 
    //VIA N*(1535)
    c->AddChannel(0.58, "p", "NS11+");
 
    //IMPORTANT: If N* is decaying into more particles, ratios have to scaled!!!
 
    //decay of the N*
    PDecayChannel *nstar_decay = new PDecayChannel;
    nstar_decay->AddChannel(1.0, "eta", "p");
    pdm->AddChannel("NS11+", nstar_decay);
 
    //decay of the eta
    PDecayChannel *eta_dalitz_decay = new PDecayChannel;
    eta_dalitz_decay->AddChannel(1, "g", "dilepton");
    pdm->AddChannel("eta", eta_dalitz_decay);
 
    //decay of the virtual photon:
    PDecayChannel *eta_dilepton_decay = new PDecayChannel;
    eta_dilepton_decay->AddChannel(1.0, "e+", "e-");
 
    pdm->AddChannel("dilepton", eta_dilepton_decay);
 
    //dim->Disable("eta_physics");
 
    TString filename("eta_dalitz_a");
    if (!eta_helicity && !pp_model) {
    dim->Disable("eta_dilepton_helicity");
    dim->Disable("pp_eta_pp_align");
    dim->Disable("pp_ns_eta_pp_align");
    } else if (eta_helicity && !pp_model) {
    filename = TString ("eta_dalitz_b");
    dim->Disable("pp_eta_pp_align");
    dim->Disable("pp_ns_eta_pp_align");
    } else if (!eta_helicity && pp_model) {
    filename = TString ("eta_dalitz_c");
    dim->Disable("eta_dilepton_helicity");
    } else {
    filename = TString ("eta_dalitz_d");
    }
 
    pdm->InitReaction(&q, c);
 
    pdm->loop(50000, 0, filename.Data(), 0, 0, 0, ascii, 1);
}