| 1 | //STARTHEADER
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| 2 | // $Id: CDFMidPointPlugin.hh,v 1.1 2008-11-06 14:32:10 ovyn Exp $
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| 3 | //
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| 4 | // Copyright (c) 2005-2006, Matteo Cacciari and Gavin Salam
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| 5 | //
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| 6 | //----------------------------------------------------------------------
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| 7 | // This file is part of FastJet.
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| 8 | //
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| 9 | // FastJet is free software; you can redistribute it and/or modify
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| 10 | // it under the terms of the GNU General Public License as published by
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| 11 | // the Free Software Foundation; either version 2 of the License, or
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| 12 | // (at your option) any later version.
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| 13 | //
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| 14 | // The algorithms that underlie FastJet have required considerable
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| 15 | // development and are described in hep-ph/0512210. If you use
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| 16 | // FastJet as part of work towards a scientific publication, please
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| 17 | // include a citation to the FastJet paper.
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| 18 | //
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| 19 | // FastJet is distributed in the hope that it will be useful,
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| 20 | // but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 21 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 22 | // GNU General Public License for more details.
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| 23 | //
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| 24 | // You should have received a copy of the GNU General Public License
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| 25 | // along with FastJet; if not, write to the Free Software
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| 26 | // Foundation, Inc.:
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| 27 | // 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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| 28 | //----------------------------------------------------------------------
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| 29 | //ENDHEADER
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| 30 |
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| 31 | #ifndef __CDFMIDPOINTPLUGIN_HH__
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| 32 | #define __CDFMIDPOINTPLUGIN_HH__
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| 33 |
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| 34 | #include "Utilities/Fastjet/include/fastjet/JetDefinition.hh"
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| 35 |
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| 36 | // questionable whether this should be in fastjet namespace or not...
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| 37 |
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| 38 | FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh
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| 39 |
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| 40 | //----------------------------------------------------------------------
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| 41 | //
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| 42 | /// CDFMidPointPlugin is a plugin for fastjet (v2.1 upwards) that
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| 43 | /// provides an interface to the CDF version of Run-II iterative cone
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| 44 | /// algorithm with midpoint seeds (also known as the Iterative Legacy
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| 45 | /// Cone Algorithm, ILCA).
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| 46 | ///
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| 47 | /// The CDF code has been taken from Joey Huston's webpage
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| 48 | /// http://www.pa.msu.edu/~huston/Les_Houches_2005/Les_Houches_SM.html
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| 49 | ///
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| 50 | /// Note that the CDF midpoint code contains options that go beyond
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| 51 | /// those described in the Tevatron run-II document (hep-ex/0005012),
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| 52 | /// notably search-cones, as described in hep-ph/0111434, and
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| 53 | /// midpoints bewteen multiplets of stable cones.
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| 54 | ///
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| 55 | /// Additionally, the version of the CDF midpoint code distributed
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| 56 | /// here has been modified by the FastJet authors, so as to allow one
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| 57 | /// to choose the scale used in the split-merge step.
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| 58 | //
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| 59 | //----------------------------------------------------------------------
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| 60 | class CDFMidPointPlugin : public JetDefinition::Plugin {
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| 61 | public:
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| 62 | /// the choice of scale to be used in the split-merge step
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| 63 | // NB: just replicates what we've added to the CDF midpoint code
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| 64 | enum SplitMergeScale {SM_pt, SM_Et, SM_mt, SM_pttilde};
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| 65 |
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| 66 | ///
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| 67 | /// A CDFMidPointPlugin constructor that looks like the one provided
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| 68 | /// by CDF. Its arguments should have the following meaning:
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| 69 | ///
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| 70 | /// - seed_threshold: minimum pt for a particle to be considered
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| 71 | /// a seed of the iteration.
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| 72 | ///
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| 73 | /// - cone_radius: standard meaning
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| 74 | ///
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| 75 | /// - cone_area_fraction: stable-cones are searched for with a
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| 76 | /// radius Rsearch = R * sqrt(cone_area_fraction), and then
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| 77 | /// expanded to size R afterwards; note (hep-ph/0610012) that this
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| 78 | /// introduces IR unsafety at NLO for X+2-jet observables (where X
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| 79 | /// any hard object).
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| 80 | ///
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| 81 | /// - max_pair_size: "midpoints" can be added between pairs of
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| 82 | /// stable cones, triplets of stable cones, etc.; max_pair_size
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| 83 | /// indicates the maximum number of stable cones that are
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| 84 | /// assembled when adding midpoints.
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| 85 | ///
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| 86 | /// - max_iterations: the maximum number of iterations to carry out
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| 87 | /// when looking for a stable cone.
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| 88 | ///
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| 89 | /// - overlap_threshold: if
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| 90 | /// (overlapping_Et)/(Et_of_softer_protojet) < overlap_threshold,
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| 91 | /// overlapping jets are split, otherwise they are merged.
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| 92 | ///
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| 93 | /// - sm_scale: a choice for the scale to be used in the split-merge
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| 94 | /// step (both for ordering the momenta and quantifying the
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| 95 | /// overlap); the three options are
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| 96 | ///
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| 97 | /// . SM_pt: pt (default -- source of small IR safety issue in purely
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| 98 | /// hadronic events)
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| 99 | ///
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| 100 | /// . SM_Et: Et (not boost invariant, reduces to mt at zero rapidity and
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| 101 | /// to pt and infinite rapidity)
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| 102 | ///
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| 103 | /// . SM_mt: transverse mass = sqrt(m^2+pt^2)
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| 104 | ///
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| 105 | CDFMidPointPlugin (
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| 106 | double seed_threshold ,
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| 107 | double cone_radius ,
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| 108 | double cone_area_fraction ,
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| 109 | int max_pair_size ,
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| 110 | int max_iterations ,
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| 111 | double overlap_threshold ,
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| 112 | SplitMergeScale sm_scale = SM_pt) :
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| 113 | _seed_threshold (seed_threshold ),
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| 114 | _cone_radius (cone_radius ),
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| 115 | _cone_area_fraction (cone_area_fraction ),
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| 116 | _max_pair_size (max_pair_size ),
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| 117 | _max_iterations (max_iterations ),
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| 118 | _overlap_threshold (overlap_threshold ),
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| 119 | _sm_scale (sm_scale) {}
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| 120 |
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| 121 | /// a compact constructor
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| 122 | CDFMidPointPlugin (double cone_radius,
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| 123 | double overlap_threshold = 0.5,
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| 124 | double seed_threshold = 1.0,
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| 125 | double cone_area_fraction = 1.0) :
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| 126 | _seed_threshold (seed_threshold ),
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| 127 | _cone_radius (cone_radius ),
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| 128 | _cone_area_fraction (cone_area_fraction ),
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| 129 | _max_pair_size (2 ),
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| 130 | _max_iterations (100 ),
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| 131 | _overlap_threshold (overlap_threshold ),
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| 132 | _sm_scale (SM_pt) {}
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| 133 |
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| 134 |
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| 135 | // some functions to return info about parameters
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| 136 | double seed_threshold () const {return _seed_threshold ;}
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| 137 | double cone_radius () const {return _cone_radius ;}
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| 138 | double cone_area_fraction () const {return _cone_area_fraction ;}
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| 139 | int max_pair_size () const {return _max_pair_size ;}
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| 140 | int max_iterations () const {return _max_iterations ;}
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| 141 | double overlap_threshold () const {return _overlap_threshold ;}
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| 142 |
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| 143 |
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| 144 | // the things that are required by base class
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| 145 | virtual std::string description () const;
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| 146 | virtual void run_clustering(ClusterSequence &) const;
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| 147 | /// the plugin mechanism's standard way of accessing the jet radius
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| 148 | virtual double R() const {return cone_radius();}
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| 149 |
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| 150 | private:
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| 151 |
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| 152 | double _seed_threshold ;
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| 153 | double _cone_radius ;
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| 154 | double _cone_area_fraction;
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| 155 | int _max_pair_size ;
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| 156 | int _max_iterations ;
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| 157 | double _overlap_threshold ;
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| 158 | SplitMergeScale _sm_scale ;
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| 159 | };
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| 160 |
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| 161 | FASTJET_END_NAMESPACE // defined in fastjet/internal/base.hh
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| 162 |
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| 163 | #endif // __CDFMIDPOINTPLUGIN_HH__
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