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Re: vertex reconstruction without fitting? [message #17470 is a reply to message #17469] Fri, 07 November 2014 20:29 Go to previous messageGo to previous message
Ralf Kliemt is currently offline  Ralf Kliemt
Messages: 507
Registered: May 2007
Location: GSI, Darmstadt
first-grade participant

From: *
Hello Anna,

This is quite straightforward and nothing special. You need to crreate a composite candidate with your part of the charged (!) final state particles. Then feed it to the fitter or POCA calculator, just as you "always do".

		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

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