FastJet  3.1.0
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ktjet_example.cc
1 //----------------------------------------------------------------------
2 // ktjet example program that should do the same thing as the
3 // fastjet_example program (as of 3 Feb 2006)
4 //
5 // NB: the ../Makefile may need to be modified to set proper
6 // paths for access to the CLHEP and KtJet libraries.
7 //----------------------------------------------------------------------
8 #include<iostream> // needed for io
9 #include<sstream> // needed for internal io
10 #include<vector>
11 
12 /** Need to include these KtJet Headers */
13 #include "KtJet/KtEvent.h"
14 #include "KtJet/KtLorentzVector.h"
15 
16 using namespace std;
17 using namespace KtJet;
18 
19 // a declaration of a function that pretty prints a list of jets
20 void print_jets (const vector<KtLorentzVector> &);
21 
22 /// an example program showing how the fastjet_example program would
23 /// be translated for use with ktjet.
24 int main (int argc, char ** argv) {
25 
26  vector<KtLorentzVector> input_particles;
27 
28  // read in input particles
29  double px, py , pz, E;
30  while (cin >> px >> py >> pz >> E) {
31  // create a KtLorentzVector with these components and put it onto
32  // back of the input_particles vector
33  input_particles.push_back(KtLorentzVector(px,py,pz,E));
34  }
35 
36  // run the inclusive jet clustering in PP mode using the covariant
37  // E-scheme for recobination (type=4, angle=2, recom=1, rparameter=1.0)
38  double Rparam = 1.0;
39  KtEvent clust_seq(input_particles,4,2,1,Rparam);
40 
41  // extract the inclusive jets with pt > 5 GeV, sorted by pt
42  double ptmin = 5.0;
43  vector<KtLorentzVector> temporary_jets = clust_seq.getJetsPt();
44  vector<KtLorentzVector> inclusive_jets;
45  for (unsigned int i = 0; i < temporary_jets.size(); i++) {
46  if (temporary_jets[i].perp() >= ptmin) {
47  inclusive_jets.push_back(temporary_jets[i]);}
48  else {break;}
49  }
50 
51  // print them out
52  cout << "Printing inclusive jets with pt > "<< ptmin<<" GeV\n";
53  cout << "---------------------------------------\n";
54  print_jets(inclusive_jets);
55  cout << endl;
56 
57  // Extract the exclusive jets with dcut = 25 GeV^2.
58  double dcut = 25.0;
59  // Note that KtJet's definition of dij differs from Ellis&Soper (and
60  // fastjet) in the case where Rparam /= 1.0 (though in this case one
61  // should perhaps not be using the exclusive kt algorithm in any case).
62  clust_seq.findJetsD(dcut * Rparam*Rparam);
63  vector<KtLorentzVector> exclusive_jets = clust_seq.getJetsPt();
64 
65  // print them out
66  cout << "Printing exclusive jets with dcut = "<< dcut<<" GeV^2\n";
67  cout << "--------------------------------------------\n";
68  print_jets(exclusive_jets);
69 
70 
71 }
72 
73 
74 //----------------------------------------------------------------------
75 // a function that pretty prints a list of jets
76 void print_jets (const vector<KtLorentzVector> & jets) {
77 
78  // label the columns
79  printf("%5s %15s %15s %15s %15s\n","jet #", "rapidity",
80  "phi", "pt", "n constituents");
81 
82  // print out the details for each jet
83  for (unsigned int i = 0; i < jets.size(); i++) {
84  int n_constituents = jets[i].getConstituents().size();
85  double phi = jets[i].phi();
86  if (phi < 0.0) {phi += 6.283185307179586476925286766559005768394;}
87  printf("%5u %15.8f %15.8f %15.8f %8u\n",
88  i, jets[i].rapidity(), phi,
89  jets[i].perp(), n_constituents);
90  }
91 
92 }
int main()
an example program showing how to use fastjet
Definition: 01-basic.cc:50
void print_jets(const vector< fastjet::PseudoJet > &)
a function that pretty prints a list of jets