//---------------------------------------------------
//
// Anna Senger a.senger@gsi.de
//
//---------------------------------------------------

void invM(TString dataSet = "muons")
{

 TH1D *invM_sgn = new TH1D("invM_omega","invM_omega",400, 0, 4);
 
 TString name= dataSet + ".ana.root";
 
 TClonesArray *MuPlus = new TClonesArray("CbmAnaMuonCandidate");
 TClonesArray *MuMinus = new TClonesArray("CbmAnaMuonCandidate");
 TTree *InputTree;

 TFile *f = new TFile(name);
 if (f->IsZombie() || f->GetNkeys() < 1 || f->TestBit(TFile::kRecovered))f->Close();

 InputTree = (TTree*)f->Get("cbmsim");  
 InputTree->SetBranchAddress("MuPlus",  &MuPlus); 
 InputTree->SetBranchAddress("MuMinus", &MuMinus); 

 for(int iEvent=0; iEvent<InputTree->GetEntries(); iEvent++){
   
   InputTree->GetEntry(iEvent);

   int NofPlus  = MuPlus->GetEntriesFast();
   int NofMinus = MuMinus->GetEntriesFast();
   
   if(NofPlus==0 || NofMinus==0)continue;
   
   for (int iPart=0; iPart<NofPlus; iPart++){
     CbmAnaMuonCandidate  *mu_pl = (CbmAnaMuonCandidate*)MuPlus->At(iPart);
     TLorentzVector *P_pl = mu_pl->GetMomentum();
     
     for (int jPart=0; jPart<NofMinus; jPart++){
       CbmAnaMuonCandidate  *mu_mn = (CbmAnaMuonCandidate*)MuMinus->At(jPart);
       TLorentzVector *P_mn = mu_mn->GetMomentum();
       TLorentzVector M(*P_pl + *P_mn);
       invM_sgn->Fill(M.M());
     }
   }
 }
 f->Close();
 
 if(invM_sgn->GetEntries()>10){
  std::cout << " Test passed" << std::endl;
  std::cout << " All ok " << std::endl;
 }

}