PndVtxPRG prgfitter(dm[j]); // instantiate vertex fitter
prgfitter.Fit(); // perform fit
RhoCandidate *dm_fit_prg = dm[j]->GetFit(); // fitted candidate
double dm_prg_chi2 = prgfitter.GetChi2(); // access chi2 of fit
double dm_prg_prob = prgfitter.GetProb(); // access probability of fit
TVector3 dmVtxPrg = dm_fit_prg->Pos(); // the vertex position
double dm_prg_x = dmVtxPrg.);
double dm_prg_y = dmVtxPrg.Y();
double dm_prg_z = dmVtxPrg.Z();
double dm_prg_mass = dm_fit_prg->M();