FastJet 3.0.2
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00001 //STARTHEADER 00002 // $Id: CDFMidPointPlugin.hh 2758 2011-11-24 08:31:58Z soyez $ 00003 // 00004 // Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez 00005 // 00006 //---------------------------------------------------------------------- 00007 // This file is part of FastJet. 00008 // 00009 // FastJet is free software; you can redistribute it and/or modify 00010 // it under the terms of the GNU General Public License as published by 00011 // the Free Software Foundation; either version 2 of the License, or 00012 // (at your option) any later version. 00013 // 00014 // The algorithms that underlie FastJet have required considerable 00015 // development and are described in hep-ph/0512210. If you use 00016 // FastJet as part of work towards a scientific publication, please 00017 // include a citation to the FastJet paper. 00018 // 00019 // FastJet is distributed in the hope that it will be useful, 00020 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00021 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00022 // GNU General Public License for more details. 00023 // 00024 // You should have received a copy of the GNU General Public License 00025 // along with FastJet. If not, see <http://www.gnu.org/licenses/>. 00026 //---------------------------------------------------------------------- 00027 //ENDHEADER 00028 00029 #ifndef __CDFMIDPOINTPLUGIN_HH__ 00030 #define __CDFMIDPOINTPLUGIN_HH__ 00031 00032 #include "fastjet/JetDefinition.hh" 00033 00034 // questionable whether this should be in fastjet namespace or not... 00035 00036 FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh 00037 00038 //---------------------------------------------------------------------- 00039 // 00040 /// @ingroup plugins 00041 /// \class CDFMidPointPlugin 00042 /// Implementation of the MidPoint algorithm from CDF (plugin for 00043 /// fastjet-v2.1 upwards) 00044 /// 00045 /// A plugin for fastjet-v2.1 that provides an interface to the CDF 00046 /// midpoint algorithm 00047 /// 00048 /// CDFMidPointPlugin is a plugin for fastjet (v2.1 upwards) that 00049 /// provides an interface to the CDF version of Run-II iterative cone 00050 /// algorithm with midpoint seeds (also known as the Iterative Legacy 00051 /// Cone Algorithm, ILCA). 00052 /// 00053 /// The CDF code has been taken from Joey Huston's webpage 00054 /// http://www.pa.msu.edu/~huston/Les_Houches_2005/Les_Houches_SM.html 00055 /// 00056 /// Note that the CDF midpoint code contains options that go beyond 00057 /// those described in the Tevatron run-II document (hep-ex/0005012), 00058 /// notably search-cones, as described in hep-ph/0111434, and 00059 /// midpoints bewteen multiplets of stable cones. 00060 /// 00061 /// Additionally, the version of the CDF midpoint code distributed 00062 /// here has been modified by the FastJet authors, so as to allow one 00063 /// to choose the scale used in the split-merge step. 00064 // 00065 //---------------------------------------------------------------------- 00066 class CDFMidPointPlugin : public JetDefinition::Plugin { 00067 public: 00068 /// the choice of scale to be used in the split-merge step 00069 // NB: just replicates what we've added to the CDF midpoint code 00070 enum SplitMergeScale {SM_pt, SM_Et, SM_mt, SM_pttilde}; 00071 00072 /// 00073 /// A CDFMidPointPlugin constructor that looks like the one provided 00074 /// by CDF. Its arguments should have the following meaning: 00075 /// 00076 /// - seed_threshold: minimum pt for a particle to be considered 00077 /// a seed of the iteration. 00078 /// 00079 /// - cone_radius: standard meaning 00080 /// 00081 /// - cone_area_fraction: stable-cones are searched for with a 00082 /// radius Rsearch = R * sqrt(cone_area_fraction), and then 00083 /// expanded to size R afterwards; note (hep-ph/0610012) that this 00084 /// introduces IR unsafety at NLO for X+2-jet observables (where X 00085 /// any hard object). 00086 /// 00087 /// - max_pair_size: "midpoints" can be added between pairs of 00088 /// stable cones, triplets of stable cones, etc.; max_pair_size 00089 /// indicates the maximum number of stable cones that are 00090 /// assembled when adding midpoints. 00091 /// 00092 /// - max_iterations: the maximum number of iterations to carry out 00093 /// when looking for a stable cone. 00094 /// 00095 /// - overlap_threshold: if 00096 /// (overlapping_Et)/(Et_of_softer_protojet) < overlap_threshold, 00097 /// overlapping jets are split, otherwise they are merged. 00098 /// 00099 /// - sm_scale: a choice for the scale to be used in the split-merge 00100 /// step (both for ordering the momenta and quantifying the 00101 /// overlap); the three options are 00102 /// 00103 /// . SM_pt: pt (default -- source of small IR safety issue in purely 00104 /// hadronic events) 00105 /// 00106 /// . SM_Et: Et (not boost invariant, reduces to mt at zero rapidity and 00107 /// to pt and infinite rapidity) 00108 /// 00109 /// . SM_mt: transverse mass = sqrt(m^2+pt^2) 00110 /// 00111 CDFMidPointPlugin ( 00112 double seed_threshold_in , 00113 double cone_radius_in , 00114 double cone_area_fraction_in , 00115 int max_pair_size_in , 00116 int max_iterations_in , 00117 double overlap_threshold_in , 00118 SplitMergeScale sm_scale_in = SM_pt) : 00119 _seed_threshold (seed_threshold_in ), 00120 _cone_radius (cone_radius_in ), 00121 _cone_area_fraction (cone_area_fraction_in ), 00122 _max_pair_size (max_pair_size_in ), 00123 _max_iterations (max_iterations_in ), 00124 _overlap_threshold (overlap_threshold_in ), 00125 _sm_scale (sm_scale_in) {} 00126 00127 /// a compact constructor 00128 /// 00129 /// NB: as of version 2.4, the default value for the 00130 /// overlap_threshold threshold has been removed, to avoid 00131 /// misleading people into using the value of 0.5 without thinking, 00132 /// which is known to have adverse effects in high-noise 00133 /// environments. A recommended value is 0.75. 00134 CDFMidPointPlugin (double cone_radius_in, 00135 double overlap_threshold_in,// = 0.5, 00136 double seed_threshold_in = 1.0, 00137 double cone_area_fraction_in = 1.0) : 00138 _seed_threshold (seed_threshold_in ), 00139 _cone_radius (cone_radius_in ), 00140 _cone_area_fraction (cone_area_fraction_in ), 00141 _max_pair_size (2 ), 00142 _max_iterations (100 ), 00143 _overlap_threshold (overlap_threshold_in ), 00144 _sm_scale (SM_pt) {} 00145 00146 00147 // some functions to return info about parameters 00148 double seed_threshold () const {return _seed_threshold ;} 00149 double cone_radius () const {return _cone_radius ;} 00150 double cone_area_fraction () const {return _cone_area_fraction ;} 00151 int max_pair_size () const {return _max_pair_size ;} 00152 int max_iterations () const {return _max_iterations ;} 00153 double overlap_threshold () const {return _overlap_threshold ;} 00154 00155 00156 // the things that are required by base class 00157 virtual std::string description () const; 00158 virtual void run_clustering(ClusterSequence &) const; 00159 /// the plugin mechanism's standard way of accessing the jet radius 00160 virtual double R() const {return cone_radius();} 00161 00162 private: 00163 00164 double _seed_threshold ; 00165 double _cone_radius ; 00166 double _cone_area_fraction; 00167 int _max_pair_size ; 00168 int _max_iterations ; 00169 double _overlap_threshold ; 00170 SplitMergeScale _sm_scale ; 00171 00172 static bool _first_time; 00173 00174 /// print a banner for reference to the 3rd-party code 00175 void _print_banner(std::ostream *ostr) const; 00176 }; 00177 00178 FASTJET_END_NAMESPACE // defined in fastjet/internal/base.hh 00179 00180 #endif // __CDFMIDPOINTPLUGIN_HH__