theAnalysis->FillList(muplus,  "MuonAllPlus");
		theAnalysis->FillList(muminus, "MuonAllMinus");
		
		// *** combinatorics for J/psi -> mu+ mu-
		jpsi.Combine(muplus, muminus);
		
		// ***
		// *** do VERTEX FIT (J/psi)
		// ***
		for (j=0;j<jpsi.GetLength();++j) 
		{
			PndKinVtxFitter vtxfitter(jpsi[j]);	// instantiate a vertex fitter
			if( ! vtxfitter.Fit(); ) continue;
			
			double chi2_vtx = vtxfitter.GetChi2();	// access chi2 of fit
			double prob_vtx = vtxfitter.GetProb();	// access probability of fit
			RhoCandidate *jfit = jpsi[j]->GetFit();	// access the fitted cand
			TVector3 jVtx=jfit->Pos();		// and the decay vertex position
		}