| 1 | /*
|
|---|
| 2 | Example of using vertex fitter class to fit primary vertex
|
|---|
| 3 | assumed to be generated in (0,0,0)
|
|---|
| 4 | */
|
|---|
| 5 |
|
|---|
| 6 | #include "classes/DelphesClasses.h"
|
|---|
| 7 | #include "external/ExRootAnalysis/ExRootTreeReader.h"
|
|---|
| 8 | #include "modules/TrackCovariance.h"
|
|---|
| 9 | #include "external/TrackCovariance/TrkUtil.h"
|
|---|
| 10 | #include "external/TrackCovariance/VertexFit.h"
|
|---|
| 11 |
|
|---|
| 12 | #include <TClonesArray.h>
|
|---|
| 13 | #include <TChain.h>
|
|---|
| 14 | #include <TVector3.h>
|
|---|
| 15 | #include <TVectorD.h>
|
|---|
| 16 | #include <TMatrixDSym.h>
|
|---|
| 17 | #include <TH1.h>
|
|---|
| 18 | #include <TCanvas.h>
|
|---|
| 19 | #include <TStyle.h>
|
|---|
| 20 |
|
|---|
| 21 | //------------------------------------------------------------------------------
|
|---|
| 22 |
|
|---|
| 23 | void ExamplePVtxFit(const char* inputFile, Int_t Nevent = 5)
|
|---|
| 24 | {
|
|---|
| 25 | // Create chain of root trees
|
|---|
| 26 | TChain chain("Delphes");
|
|---|
| 27 | chain.Add(inputFile);
|
|---|
| 28 |
|
|---|
| 29 | // Create object of class ExRootTreeReader
|
|---|
| 30 | ExRootTreeReader* treeReader = new ExRootTreeReader(&chain);
|
|---|
| 31 | Long64_t numberOfEntries = treeReader->GetEntries();
|
|---|
| 32 |
|
|---|
| 33 | // Get pointers to branches used in this analysis
|
|---|
| 34 | TClonesArray* branchGenPart = treeReader->UseBranch("Particle");
|
|---|
| 35 | TClonesArray* branchTrack = treeReader->UseBranch("Track");
|
|---|
| 36 |
|
|---|
| 37 | // Book histograms
|
|---|
| 38 | Int_t Nbin = 100;
|
|---|
| 39 | TH1D* hXpull = new TH1D("hXpull", "Pull X vertex component", Nbin, -10., 10.);
|
|---|
| 40 | TH1D* hYpull = new TH1D("hYpull", "Pull Y vertex component", Nbin, -10., 10.);
|
|---|
| 41 | TH1D* hZpull = new TH1D("hZpull", "Pull Z vertex component", Nbin, -10., 10.);
|
|---|
| 42 | TH1D* hChi2 = new TH1D("hChi2", "Vertex #chi^{2}/N_{dof}", Nbin, 0., 10.);
|
|---|
| 43 | //
|
|---|
| 44 | // Loop over all events
|
|---|
| 45 | Int_t Nev = TMath::Min(Nevent, (Int_t) numberOfEntries);
|
|---|
| 46 | for (Int_t entry = 0; entry < Nev; ++entry)
|
|---|
| 47 | {
|
|---|
| 48 | // Load selected branches with data from specified event
|
|---|
| 49 | treeReader->ReadEntry(entry);
|
|---|
| 50 | Int_t Ntr = 0; // # of tracks from primary vertex
|
|---|
| 51 | Int_t NtrG = branchTrack->GetEntries();
|
|---|
| 52 | TVectorD** pr = new TVectorD * [NtrG];
|
|---|
| 53 | TMatrixDSym** cv = new TMatrixDSym * [NtrG];
|
|---|
| 54 | // If event contains at least 1 track
|
|---|
| 55 | //
|
|---|
| 56 | if (branchTrack->GetEntries() > 0)
|
|---|
| 57 | {
|
|---|
| 58 | // Loop on tracks
|
|---|
| 59 | for (Int_t it = 0; it < branchTrack->GetEntries(); it++)
|
|---|
| 60 | {
|
|---|
| 61 | Track* trk = (Track*)branchTrack->At(it);
|
|---|
| 62 | //
|
|---|
| 63 | // Get associated generated particle
|
|---|
| 64 | GenParticle* gp = (GenParticle*)trk->Particle.GetObject();
|
|---|
| 65 | //
|
|---|
| 66 | // Position of origin in meters
|
|---|
| 67 | Double_t x = 1.0e-3 * gp->X;
|
|---|
| 68 | Double_t y = 1.0e-3 * gp->Y;
|
|---|
| 69 | Double_t z = 1.0e-3 * gp->Z;
|
|---|
| 70 | //
|
|---|
| 71 | // group tracks originating from the primary vertex
|
|---|
| 72 | if (x == 0.0 && y == 0.0)
|
|---|
| 73 | {
|
|---|
| 74 | //
|
|---|
| 75 | // Reconstructed track parameters
|
|---|
| 76 | Double_t obsD0 = trk->D0;
|
|---|
| 77 | Double_t obsPhi = trk->Phi;
|
|---|
| 78 | Double_t obsC = trk->C;
|
|---|
| 79 | Double_t obsZ0 = trk->DZ;
|
|---|
| 80 | Double_t obsCtg = trk->CtgTheta;
|
|---|
| 81 | Double_t oPar[5] = { obsD0, obsPhi, obsC, obsZ0, obsCtg };
|
|---|
| 82 | TVectorD obsPar(5, oPar); // Fill observed parameters
|
|---|
| 83 | TVector3 xv(x, y, z);
|
|---|
| 84 | //
|
|---|
| 85 | pr[Ntr] = new TVectorD(obsPar);
|
|---|
| 86 | cv[Ntr] = new TMatrixDSym(TrkUtil::CovToMm(trk->CovarianceMatrix()));
|
|---|
| 87 | Ntr++;
|
|---|
| 88 | }
|
|---|
| 89 | } // End loop on tracks
|
|---|
| 90 | //std::cout << "Total of " << Ntr << " primary tracks out of " << NtrG << " tracks" << std::endl;
|
|---|
| 91 | }
|
|---|
| 92 | //
|
|---|
| 93 | // Fit primary vertex
|
|---|
| 94 | Int_t MinTrk = 2; // Minumum # tracks for vertex fit
|
|---|
| 95 | if (Ntr >= MinTrk) {
|
|---|
| 96 | VertexFit* Vtx = new VertexFit(Ntr, pr, cv);
|
|---|
| 97 | TVectorD xvtx = Vtx->GetVtx();
|
|---|
| 98 | TMatrixDSym covX = Vtx->GetVtxCov();
|
|---|
| 99 | Double_t Chi2 = Vtx->GetVtxChi2();
|
|---|
| 100 | Double_t Ndof = 2 * (Double_t)Ntr - 3;
|
|---|
| 101 | Double_t PullX = xvtx(0) / TMath::Sqrt(covX(0, 0));
|
|---|
| 102 | Double_t PullY = xvtx(1) / TMath::Sqrt(covX(1, 1));
|
|---|
| 103 | Double_t PullZ = xvtx(2) / TMath::Sqrt(covX(2, 2));
|
|---|
| 104 | //
|
|---|
| 105 | // Fill histograms
|
|---|
| 106 | hXpull->Fill(PullX);
|
|---|
| 107 | hYpull->Fill(PullY);
|
|---|
| 108 | hZpull->Fill(PullZ);
|
|---|
| 109 | hChi2->Fill(Chi2 / Ndof);
|
|---|
| 110 | }
|
|---|
| 111 |
|
|---|
| 112 | //std::cout << "Vertex chi2/Ndof = " << Chi2 / Ndof << std::endl;
|
|---|
| 113 | //
|
|---|
| 114 | // Cleanup
|
|---|
| 115 | for (Int_t i = 0; i < Ntr; i++) delete pr[i];
|
|---|
| 116 | for (Int_t i = 0; i < Ntr; i++) delete cv[i];
|
|---|
| 117 | delete[] pr;
|
|---|
| 118 | delete[] cv;
|
|---|
| 119 | }
|
|---|
| 120 | //
|
|---|
| 121 | // Show resulting histograms
|
|---|
| 122 | //
|
|---|
| 123 | TCanvas* Cnv = new TCanvas("Cnv", "Delphes generated track plots", 50, 50, 900, 500);
|
|---|
| 124 | Cnv->Divide(2, 2);
|
|---|
| 125 | Cnv->cd(1); gPad->SetLogy(1); gStyle->SetOptFit(1111);
|
|---|
| 126 | hXpull->Fit("gaus"); hXpull->Draw();
|
|---|
| 127 | Cnv->cd(2); gPad->SetLogy(1); gStyle->SetOptFit(1111);
|
|---|
| 128 | hYpull->Fit("gaus"); hYpull->Draw();
|
|---|
| 129 | Cnv->cd(3); gPad->SetLogy(1); gStyle->SetOptFit(1111);
|
|---|
| 130 | hZpull->Fit("gaus"); hZpull->Draw();
|
|---|
| 131 | Cnv->cd(4); hChi2->Draw();
|
|---|
| 132 | }
|
|---|
