test_phi2170.C

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void test_phi2170(
    Int_t decay_mode = 0,     // decay channel (see below)
    Int_t nev = 1000,         // number of events
    Double_t Tbeam = 29.0     // proton beam kinetic energy [GeV]
){
    //
    // Example reaction channels currently used for the CBM
    // φ(2170) feasibility studies.
    //
    // decay_mode:
    //   0 -> φ π+ π−
    //   1 -> K+ K− π+ π−
    //   2 -> φ f0(980)
    //
    // Additional decay channels can be added as needed.
    //
 
    // ============================================================
    // Beam kinetic-energy as input
    // ============================================================
    // Use the TString/parser constructor so the first argument is
    // interpreted as proton beam kinetic energy [GeV].
    // The Double_t PReaction overload interprets the first argument
    // as beam momentum [GeV/c].
    TString Tbeam_str;
    Tbeam_str.Form("%.6f", Tbeam);
 
    TString reaction;
    TString outfile;
    TString mode_name;
 
    switch (decay_mode) {
 
        case 0:
            reaction = "p p phi2170 [phi [K+ K-] pi+ pi-]";
            outfile  = "phi2170_phipipi";
            mode_name = "phi pi+ pi-";
            break;
 
        case 1:
            reaction = "p p phi2170 [K+ K- pi+ pi-]";
            outfile  = "phi2170_KKpipi";
            mode_name = "K+ K- pi+ pi-";
            break;
 
        case 2:
            reaction = "p p phi2170 [phi [K+ K-] f0_980 [pi+ pi-]]";
            outfile  = "phi2170_phif0";
            mode_name = "phi f0(980)";
            break;
 
        default:
            Error("test_phi2170",
                  "Unknown decay mode %d (allowed: 0, 1, 2)",
                  decay_mode);
            return;
    }
 
    // Add number-of-events tag
    TString nev_tag;
    if (nev >= 1000 && nev % 1000 == 0) {
        nev_tag.Form("_%dk", nev / 1000);
    }
    else {
        nev_tag.Form("_%d", nev);
    }
    outfile += nev_tag;
 
    // Add beam-energy tag
    TString energy_tag;
    energy_tag.Form("_Tbeam%.1fGeV", Tbeam);
    energy_tag.ReplaceAll(".", "p");
    outfile += energy_tag;
 
    PReaction r(Tbeam_str.Data(),
                "p",
                "p",
                reaction.Data(),
                outfile.Data());
 
    listParticle("f0_980");
    listParticle("phi2170");
 
    cout << endl;
    cout << "==========================================" << endl;
    cout << "phi(2170) example generation" << endl;
    cout << "==========================================" << endl;
    cout << "Beam kinetic energy : " << Tbeam << " GeV" << endl;
    cout << "Events      : " << nev << endl;
    cout << "Decay mode  : " << decay_mode << " (" << mode_name << ")" << endl;
    cout << "Reaction    : " << reaction << endl;
    cout << "Output      : " << outfile << ".root" << endl;
    cout << "==========================================" << endl;
    cout << endl;
    cout << "Inspect with : root -l -q 'inspect_phi2170.C(\"" << outfile << ".root\")'" << endl;
    cout << endl;
    cout << "==========================================" << endl;
    cout << endl;
 
    r.Print();
 
    r.Loop(nev);
}