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//----------------------------------------------------------------------
/// \file
/// \page Example05 05 - using e+e- algorithms
///
/// illustrate the use of e^+ e^- algorithms
///
/// They mostly differ from the pp algorithm by the fact that rather
/// than using a radius parameter and inclusive jets, they use
/// exclusive jets in one of the following ways:
/// - a fixed number of them
/// - with a dcut
/// - with a ycut
///
/// Note that natively, FastJet includes the kt (ee_kt_algorithm) and
/// genkt (ee_genkt_algorithm) algorithms. Others (like Cambridge for
/// e+ e-, Jade or SISCone in spherical coordinates) are available as
/// plugins (see 03-plugin.cc)
///
/// run it with : ./05-eplus_eminus < data/single-ee-event.dat
///
/// Source code: 05-eplus_eminus.cc
//----------------------------------------------------------------------
//STARTHEADER
// $Id: 05-eplus_eminus.cc 2684 2011-11-14 07:41:44Z soyez $
//
// Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
//
//----------------------------------------------------------------------
// This file is part of FastJet.
//
// FastJet is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// The algorithms that underlie FastJet have required considerable
// development and are described in hep-ph/0512210. If you use
// FastJet as part of work towards a scientific publication, please
// include a citation to the FastJet paper.
//
// FastJet is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with FastJet. If not, see <http://www.gnu.org/licenses/>.
//----------------------------------------------------------------------
//ENDHEADER
#include "fastjet/ClusterSequence.hh"
#include <iostream> // needed for io
#include <cstdio> // needed for io
using namespace std;
/// an example program showing how to use fastjet
int main(){
// read in input particles
//----------------------------------------------------------
vector<fastjet::PseudoJet> input_particles;
double px, py , pz, E;
while (cin >> px >> py >> pz >> E) {
// create a fastjet::PseudoJet with these components and put it onto
// back of the input_particles vector
input_particles.push_back(fastjet::PseudoJet(px,py,pz,E));
}
// create a jet definition for the kt algorithm (note that one
// should not specify an R value here)
//----------------------------------------------------------
fastjet::JetDefinition jet_def(fastjet::ee_kt_algorithm);
// run the jet clustering with the above jet definition
//----------------------------------------------------------
fastjet::ClusterSequence clust_seq(input_particles, jet_def);
// get 3 exclusive jets
//----------------------------------------------------------
int n = 3;
vector<fastjet::PseudoJet> exclusive_jets = clust_seq.exclusive_jets(n);
// tell the user what was done
// - the description of the algorithm used
// - extract the inclusive jets with pt > 5 GeV
// show the output as
// {index, rap, phi, pt, number of constituents}
//----------------------------------------------------------
cout << "Ran " << jet_def.description() << endl;
// label the columns
printf("%5s %15s\n","jet #", "E");
// print out the details for each jet
for (unsigned int i = 0; i < exclusive_jets.size(); i++) {
printf("%5u %15.8f\n",
i, exclusive_jets[i].perp());
}
return 0;
}
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