fastjet: fastjet::PxConePlugin Class Reference

given a ClusterSequence that has been filled up with initial particles, the following function should fill up the rest of the ClusterSequence, using the following member functions of ClusterSequence:

00058                                                                    {
00059  
00060   // only have hh mode
00061   int mode = 2;
00062 
00063   int    ntrak = clust_seq.jets().size(), itkdm = 4;
00064   double *ptrak = new double[ntrak*4+1];
00065   for (int i = 0; i < ntrak; i++) {
00066     ptrak[4*i+0] = clust_seq.jets()[i].px();
00067     ptrak[4*i+1] = clust_seq.jets()[i].py();
00068     ptrak[4*i+2] = clust_seq.jets()[i].pz();
00069     ptrak[4*i+3] = clust_seq.jets()[i].E();
00070   }  
00071 
00072   // max number of allowed jets
00073   int mxjet = ntrak;
00074   int njet;
00075   double *pjet  = new double[mxjet*5+1];
00076   int    *ipass = new int[ntrak+1];
00077   int    *ijmul = new int[mxjet+1];
00078   int ierr;
00079 
00080   // run pxcone
00081   pxcone(
00082     mode   ,    // 1=>e+e-, 2=>hadron-hadron
00083     ntrak  ,    // Number of particles
00084     itkdm  ,    // First dimension of PTRAK array: 
00085     ptrak  ,    // Array of particle 4-momenta (Px,Py,Pz,E)
00086     cone_radius()  ,    // Cone size (half angle) in radians
00087     min_jet_energy() ,    // Minimum Jet energy (GeV)
00088     overlap_threshold()  ,    // Maximum fraction of overlap energy in a jet
00089     mxjet  ,    // Maximum possible number of jets
00090     njet   ,    // Number of jets found
00091     pjet ,       // 5-vectors of jets
00092     ipass,      // Particle k belongs to jet number IPASS(k)-1
00093                 // IPASS = -1 if not assosciated to a jet
00094     ijmul,      // Jet i contains IJMUL[i] particles
00095     ierr        // = 0 if all is OK ;   = -1 otherwise
00096     );
00097 
00098   if (ierr != 0) throw Error("An error occurred while running PXCONE");
00099 
00100   // now transfer information back 
00101   valarray<int> last_index_created(njet);
00102 
00103   vector<vector<int> > jet_particle_content(njet);
00104 
00105   // get a list of particles in each jet
00106   for (int itrak = 0; itrak < ntrak; itrak++) {
00107     int jet_i = ipass[itrak] - 1;
00108     if (jet_i >= 0) jet_particle_content[jet_i].push_back(itrak);
00109   }
00110 
00111   // now transfer the jets back into our own structure -- we will
00112   // mimic the cone code with a sequential recombination sequence in
00113   // which the jets are built up by adding one particle at a time
00114   for(int ipxjet = njet-1; ipxjet >= 0; ipxjet--) {
00115     const vector<int> & jet_trak_list = jet_particle_content[ipxjet];
00116     int jet_k = jet_trak_list[0];
00117   
00118     for (unsigned ilist = 1; ilist < jet_trak_list.size(); ilist++) {
00119       int jet_i = jet_k;
00120       // retrieve our misappropriated index for the jet
00121       int jet_j = jet_trak_list[ilist];
00122       // do a fake recombination step with dij=0
00123       double dij = 0.0;
00124       //clust_seq.plugin_record_ij_recombination(jet_i, jet_j, dij, jet_k);
00125       if (ilist != jet_trak_list.size()-1 || E_scheme_jets()) {
00126         // our E-scheme recombination in cases where it doesn't matter
00127         clust_seq.plugin_record_ij_recombination(jet_i, jet_j, dij, jet_k);
00128       } else {
00129         // put in pxcone's momentum for the last recombination so that the
00130         // final inclusive jet corresponds exactly to PXCONE's
00131         clust_seq.plugin_record_ij_recombination(jet_i, jet_j, dij, 
00132                                 PseudoJet(pjet[5*ipxjet+0],pjet[5*ipxjet+1],
00133                                           pjet[5*ipxjet+2],pjet[5*ipxjet+3]),
00134                                                  jet_k);
00135       }
00136     }
00137   
00138     // NB: put a sensible looking d_iB just to be nice...
00139     double d_iB = clust_seq.jets()[jet_k].perp2();
00140     clust_seq.plugin_record_iB_recombination(jet_k, d_iB);
00141   }
00142 
00143 
00145   //cout << endl;
00146   //for (int ijet = 0; ijet < njet; ijet++) {
00147   //  PseudoJet jet(pjet[ijet][0],pjet[ijet][1],pjet[ijet][2],pjet[ijet][3]);
00148   //  cout << jet.perp() << " " << jet.rap() << endl;
00149   //}
00150   //cout << "-----------------------------------------------------\n";
00151   //vector<PseudoJet> ourjets(clust_seq.inclusive_jets());
00152   //for (vector<PseudoJet>::const_iterator ourjet = ourjets.begin();
00153   //     ourjet != ourjets.end(); ourjet++) {
00154   //  cout << ourjet->perp() << " " << ourjet->rap() << endl;
00155   //}
00157 
00158   delete[] ptrak;
00159   delete[] ipass;
00160   delete[] ijmul;
00161   delete[] pjet;
00162 }


Public Member Functions
	PxConePlugin (double cone_radius, double min_jet_energy=5.0, double overlap_threshold=0.5, bool E_scheme_jets=false)
	constructor for the PxConePlugin, whose arguments have the following meaning:
double	cone_radius () const
	the cone radius
double	min_jet_energy () const
	minimum jet energy (protojets below this are thrown own before merging/splitting) -- called epslon in pxcone
double	overlap_threshold () const
	Maximum fraction of overlap energy in a jet -- called ovlim in pxcone.
bool	E_scheme_jets () const
	if true then the final jets are returned as the E-scheme recombination of the particle momenta (by default, pxcone returns massless jets with a mean phi,eta type of recombination); regardless of what is returned, the internal pxcone jet-finding procedure is unaffected.
virtual std::string	description () const
	return a textual description of the jet-definition implemented in this plugin
virtual void	run_clustering (ClusterSequence &) const
	given a ClusterSequence that has been filled up with initial particles, the following function should fill up the rest of the ClusterSequence, using the following member functions of ClusterSequence: plugin_do_ij_recombination(.
virtual double	R () const
	the plugin mechanism's standard way of accessing the jet radius
Private Attributes
double	_cone_radius
double	_min_jet_energy
double	_overlap_threshold
bool	_E_scheme_jets

fastjet::PxConePlugin Class Reference

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation