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D0RunIIConePlugin.cc
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2 // $Id: D0RunIIConePlugin.cc 2815 2011-12-13 21:54:40Z soyez $
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28 
29 #include "fastjet/D0RunIIConePlugin.hh"
30 #include "fastjet/ClusterSequence.hh"
31 #include "fastjet/Error.hh"
32 #include <sstream>
33 
34 // D0 stuff
35 #include <list>
36 #include "ILConeAlgorithm.hpp"
37 #include "HepEntity.h"
38 
39 FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh
40 
41 using namespace std;
42 using namespace d0;
43 
44 const double D0RunIIConePlugin::_DEFAULT_split_ratio = 0.5 ; // overlap threshold
45 const double D0RunIIConePlugin::_DEFAULT_far_ratio = 0.5 ;
46 const double D0RunIIConePlugin::_DEFAULT_Et_min_ratio = 0.5 ;
47 const bool D0RunIIConePlugin::_DEFAULT_kill_duplicate = true ;
48 const double D0RunIIConePlugin::_DEFAULT_duplicate_dR = 0.005;
49 const double D0RunIIConePlugin::_DEFAULT_duplicate_dPT = 0.01 ;
50 const double D0RunIIConePlugin::_DEFAULT_search_factor = 1.0 ;
51 const double D0RunIIConePlugin::_DEFAULT_pT_min_leading_protojet = 0. ;
52 const double D0RunIIConePlugin::_DEFAULT_pT_min_second_protojet = 0. ;
53 const int D0RunIIConePlugin::_DEFAULT_merge_max = 10000;
54 const double D0RunIIConePlugin::_DEFAULT_pT_min_nomerge = 0. ;
55 
56 bool D0RunIIConePlugin::_first_time = true;
57 
58 string D0RunIIConePlugin::description () const {
59  ostringstream desc;
60 
61  desc << "D0 Run II Improved Legacy (midpoint) cone jet algorithm, with ";
62  desc << "cone_radius = " << cone_radius () << ", "
63  << "min_jet_Et = " << min_jet_Et () << ", "
64  << "split_ratio = " << split_ratio ();
65 
66  return desc.str();
67 }
68 
69 
70 void D0RunIIConePlugin::run_clustering(ClusterSequence & clust_seq) const {
71  // print a banner if we run this for the first time
72  _print_banner(clust_seq.fastjet_banner_stream());
73 
74  // create the entities needed by the D0 code
75  vector<HepEntity> entities(clust_seq.jets().size());
76  list<const HepEntity * > ensemble;
77  for (unsigned i = 0; i < clust_seq.jets().size(); i++) {
78  entities[i].Fill(clust_seq.jets()[i].E(),
79  clust_seq.jets()[i].px(),
80  clust_seq.jets()[i].py(),
81  clust_seq.jets()[i].pz(),
82  i);
83  // use only the particles that do not have infinite rapidity
84  if (abs(entities[i].pz) < entities[i].E) {
85  ensemble.push_back(& (entities[i]));
86  }
87  }
88 
89  // prepare the D0 algorithm
90  ILConeAlgorithm<HepEntity>
91  ilegac(cone_radius(),
92  min_jet_Et(),
93  split_ratio(),
94  far_ratio(),
95  Et_min_ratio(),
96  kill_duplicate(),
97  duplicate_dR(),
98  duplicate_dPT(),
99  search_factor(),
100  pT_min_leading_protojet(),
101  pT_min_second_protojet(),
102  merge_max(),
103  pT_min_nomerge());
104 
105  // run the algorithm
106  float Item_ET_Threshold = 0.;
107  list<HepEntity> jets;
108  ilegac.makeClusters(jets, ensemble, Item_ET_Threshold);
109 
110  // now transfer the information about the jets into the
111  // FastJet structure
112  for(int i = ilegac.ilcv.size()-1; i >= 0; i--) {
113 
114  std::list<const HepEntity*> tlist = ilegac.ilcv[i].LItems();
115  std::list<const HepEntity*>::iterator tk;
116 
117  // get first particle in list
118  tk = tlist.begin();
119 
120  // if there is no particle, just discard it
121  // Note: this unexpected behaviour has been observed when the
122  // min_jet_Et parameter was set to 0
123  if (tk==tlist.end())
124  continue;
125 
126  int jet_k = (*tk)->index;
127  // now merge with remaining particles in list
128  tk++;
129  for (; tk != tlist.end(); tk++) {
130  int jet_i = jet_k;
131  int jet_j = (*tk)->index;
132  // do a fake recombination step with dij=0
133  double dij = 0.0;
134  clust_seq.plugin_record_ij_recombination(jet_i, jet_j, dij, jet_k);
135  }
136 
137  // NB: put a sensible looking d_iB just to be nice...
138  double d_iB = clust_seq.jets()[jet_k].perp2();
139  clust_seq.plugin_record_iB_recombination(jet_k, d_iB);
140 
141  }
142 }
143 
144 // print a banner for reference to the 3rd-party code
145 void D0RunIIConePlugin::_print_banner(ostream *ostr) const{
146  if (! _first_time) return;
147  _first_time=false;
148 
149  // make sure the user has not set the banner stream to NULL
150  if (!ostr) return;
151 
152  (*ostr) << "#--------------------------------------------------------------------------" << endl;
153  (*ostr) << "# You are running the D0 Run II Cone plugin for FastJet " << endl;
154  (*ostr) << "# Original code by the D0 collaboration, provided by Lars Sonnenschein; " << endl;
155  (*ostr) << "# interface by FastJet authors " << endl;
156  (*ostr) << "# If you use this plugin, please cite " << endl;
157  (*ostr) << "# G. C. Blazey et al., hep-ex/0005012 " << endl;
158  (*ostr) << "# V. M. Abazov et al. [D0 Collaboration], arXiv:1110.3771 [hep-ex] " << endl;
159  (*ostr) << "# in addition to the usual FastJet reference. " << endl;
160  (*ostr) << "#--------------------------------------------------------------------------" << endl;
161 
162  // make sure we really have the output done.
163  ostr->flush();
164 }
165 
166 FASTJET_END_NAMESPACE // defined in fastjet/internal/base.hh