user_w_dalitz_ff.C

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//TITLE Demo using the batch syntax to change the omega form factor
 
{
    PSimpleVMDFF *ff = new PSimpleVMDFF("vmd_ff_dd@w_to_dilepton_pi0/formfactor",
                    "VMD form factor", -1);
    //use either the AddEquation or the SetVectorMesonMass version
    ff->AddEquation("_ff2 = 0.17918225/( (0.4225- _q2)*(0.4225- _q2) + 0.000676)");
    //ff->SetVectorMesonMass(0.77);
    makeDistributionManager()->Add(ff);
    
    PReaction my_reaction("2.2", "p", "p", "p p w [dilepton [e+ e-] pi0]");
    my_reaction.Print();
   
    //This is for on-line debugging
    TH1F *histo1 = new TH1F ("histo1", "ee invariant mass", 100, 0., 0.8);
    histo1->Sumw2();
    my_reaction.Do(histo1, "_x = ([e+,1] + [e-,1])->M()");
    
    my_reaction.Loop(10000);
    
    histo1->Draw("");    
}