[d7d2da3] | 1 | #ifndef __FASTJET_JH_TOP_TAGGER_HH__
|
---|
| 2 | #define __FASTJET_JH_TOP_TAGGER_HH__
|
---|
| 3 |
|
---|
[35cdc46] | 4 | //FJSTARTHEADER
|
---|
[b7b836a] | 5 | // $Id: JHTopTagger.hh 4354 2018-04-22 07:12:37Z salam $
|
---|
[d7d2da3] | 6 | //
|
---|
[b7b836a] | 7 | // Copyright (c) 2005-2018, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
|
---|
[d7d2da3] | 8 | //
|
---|
| 9 | //----------------------------------------------------------------------
|
---|
| 10 | // This file is part of FastJet.
|
---|
| 11 | //
|
---|
| 12 | // FastJet is free software; you can redistribute it and/or modify
|
---|
| 13 | // it under the terms of the GNU General Public License as published by
|
---|
| 14 | // the Free Software Foundation; either version 2 of the License, or
|
---|
| 15 | // (at your option) any later version.
|
---|
| 16 | //
|
---|
| 17 | // The algorithms that underlie FastJet have required considerable
|
---|
[35cdc46] | 18 | // development. They are described in the original FastJet paper,
|
---|
| 19 | // hep-ph/0512210 and in the manual, arXiv:1111.6097. If you use
|
---|
[d7d2da3] | 20 | // FastJet as part of work towards a scientific publication, please
|
---|
[35cdc46] | 21 | // quote the version you use and include a citation to the manual and
|
---|
| 22 | // optionally also to hep-ph/0512210.
|
---|
[d7d2da3] | 23 | //
|
---|
| 24 | // FastJet is distributed in the hope that it will be useful,
|
---|
| 25 | // but WITHOUT ANY WARRANTY; without even the implied warranty of
|
---|
| 26 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
---|
| 27 | // GNU General Public License for more details.
|
---|
| 28 | //
|
---|
| 29 | // You should have received a copy of the GNU General Public License
|
---|
| 30 | // along with FastJet. If not, see <http://www.gnu.org/licenses/>.
|
---|
| 31 | //----------------------------------------------------------------------
|
---|
[35cdc46] | 32 | //FJENDHEADER
|
---|
[d7d2da3] | 33 |
|
---|
| 34 |
|
---|
| 35 | #include <fastjet/tools/TopTaggerBase.hh>
|
---|
| 36 | #include <fastjet/CompositeJetStructure.hh>
|
---|
| 37 | #include <fastjet/LimitedWarning.hh>
|
---|
| 38 |
|
---|
| 39 | FASTJET_BEGIN_NAMESPACE
|
---|
| 40 |
|
---|
| 41 | class JHTopTagger;
|
---|
| 42 | class JHTopTaggerStructure;
|
---|
| 43 |
|
---|
| 44 | //----------------------------------------------------------------------
|
---|
| 45 | /// @ingroup tools_taggers
|
---|
| 46 | /// \class JHTopTagger
|
---|
| 47 | /// Class that helps perform boosted top tagging using the "Johns Hopkins"
|
---|
| 48 | /// method from arXiv:0806.0848 (Kaplan, Rehermann, Schwartz
|
---|
| 49 | /// and Tweedie)
|
---|
| 50 | ///
|
---|
| 51 | ///The tagger proceeds as follows:
|
---|
| 52 | /// - start from a jet J obtained with the Cambridge/Aachen algorithm
|
---|
| 53 | /// - undo the last iteration j -> j_1,j_2 (with pt_1>pt_2) until the
|
---|
| 54 | /// two subjets satisfy pt_1 > delta_p pt_J (with pt_J the pt of
|
---|
| 55 | /// the original jet) and |y_1 - y_2| + |phi_1 - phi_2| > delta_r.
|
---|
| 56 | /// - if one of these criteria is not satisfied, carry on the
|
---|
| 57 | /// procedure with j_1 (discarding j_2)
|
---|
| 58 | /// - for each of the subjets found, repeat the procedure. If some
|
---|
| 59 | /// new substructure is found, keep these 2 new subjets, otherwise
|
---|
| 60 | /// keep the original subjet (found during the first iteration)
|
---|
| 61 | /// - at this stage, one has at most 4 subjets. If one has less than
|
---|
| 62 | /// 3, the tagger has failed.
|
---|
| 63 | /// - reconstruct the W from the 2 subjets with a mass closest to the
|
---|
| 64 | /// W mass
|
---|
| 65 | /// - impose that the W helicity angle be less than a threshold
|
---|
| 66 | /// cos_theta_W_max.
|
---|
| 67 | ///
|
---|
| 68 | /// \section input Input conditions
|
---|
| 69 | ///
|
---|
| 70 | /// - the original jet must have an associated (and valid)
|
---|
| 71 | /// ClusterSequence
|
---|
| 72 | /// - the tagger is designed to work with jets formed by the
|
---|
| 73 | /// Cambridge/Aachen (C/A) algorithm; if a non-C/A jet is passed to
|
---|
| 74 | /// the tagger, a warning will be issued
|
---|
| 75 | ///
|
---|
| 76 | /// \section Example
|
---|
| 77 | ///
|
---|
| 78 | /// A JHTopTagger can be used as follows:
|
---|
| 79 | ///
|
---|
| 80 | /// \code
|
---|
| 81 | /// double delta_p = 0.10; // subjets must carry at least this fraction of the original jet's p_t
|
---|
| 82 | /// double delta_r = 0.19; // subjets must be separated by at least this Manhattan distance
|
---|
| 83 | /// double cos_theta_W_max = 0.7; // the maximal allowed value of the W helicity angle
|
---|
| 84 | /// JHTopTagger top_tagger(delta_p, delta_r, cos_theta_W_max);
|
---|
| 85 | /// // indicate the acceptable range of top, W masses (default: no limits)
|
---|
| 86 | /// top_tagger.set_top_selector(SelectorMassRange(150,200));
|
---|
| 87 | /// top_tagger.set_W_selector (SelectorMassRange( 65, 95));
|
---|
| 88 | /// // now try and tag a jet
|
---|
| 89 | /// PseudoJet top_candidate = top_tagger(jet); // jet should come from a Cambridge/Aachen clustering
|
---|
| 90 | /// if (top_candidate != 0) { // successful tagging
|
---|
| 91 | /// double top_mass = top_candidate.m();
|
---|
| 92 | /// double W_mass = top_candidate.structure_of<JHTopTagger>().W().m();
|
---|
| 93 | /// }
|
---|
| 94 | /// \endcode
|
---|
| 95 | ///
|
---|
| 96 | /// The full set of information available from the structure_of<JHTopTagger>()
|
---|
| 97 | /// call is
|
---|
| 98 | ///
|
---|
| 99 | /// - PseudoJet W() : the W subjet of the top candidate
|
---|
| 100 | /// - PseudoJet non_W(): non-W subjet(s) of the top candidate (i.e. the b)
|
---|
| 101 | /// - double cos_theta_W(): the W helicity angle
|
---|
| 102 | /// - PseudoJet W1(): the harder of the two prongs of the W
|
---|
| 103 | /// - PseudoJet W2(): the softer of the two prongs of the W
|
---|
| 104 | ///
|
---|
| 105 | /// The structure of the top_candidate can also be accessed through its
|
---|
| 106 | /// pieces() function:
|
---|
| 107 | ///
|
---|
| 108 | /// - top_candidate.pieces()[0]: W
|
---|
| 109 | /// - top_candidate.pieces()[1]: non_W
|
---|
| 110 | ///
|
---|
| 111 | /// The W itself has two pieces (corresponding to W1, W2).
|
---|
| 112 | ///
|
---|
| 113 | /// The existence of the first two of the structural calls (W(),
|
---|
| 114 | /// non_W()) and the fact that the top is made of two pieces (W,
|
---|
| 115 | /// non_W) are features that should be common to all taggers derived
|
---|
| 116 | /// from TopTaggerBase.
|
---|
| 117 | ///
|
---|
| 118 | /// See also \subpage Example13 for a full usage example.
|
---|
| 119 | ///
|
---|
| 120 | class JHTopTagger : public TopTaggerBase {
|
---|
| 121 | public:
|
---|
| 122 | /// default ctor
|
---|
| 123 | /// The parameters are the following:
|
---|
| 124 | /// \param delta_p fractional pt cut imposed on the subjets
|
---|
| 125 | /// (computed as a fraction of the original jet)
|
---|
| 126 | /// \param delta_r minimal distance between 2 subjets
|
---|
| 127 | /// (computed as |y1-y2|+|phi1-phi2|)
|
---|
| 128 | /// \param cos_theta_W_max the maximal value for the polarisation
|
---|
| 129 | /// angle of the W
|
---|
| 130 | /// \param mW the W mass
|
---|
| 131 | ///
|
---|
| 132 | /// The default values of all these parameters are taken from
|
---|
| 133 | /// arXiv:0806:0848
|
---|
| 134 | JHTopTagger(const double delta_p=0.10, const double delta_r=0.19,
|
---|
| 135 | double cos_theta_W_max=0.7, double mW=80.4)
|
---|
| 136 | : _delta_p(delta_p), _delta_r(delta_r),
|
---|
| 137 | _cos_theta_W_max(cos_theta_W_max), _mW(mW){};
|
---|
| 138 |
|
---|
| 139 | /// returns a textual description of the tagger
|
---|
| 140 | virtual std::string description() const;
|
---|
| 141 |
|
---|
| 142 | /// runs the tagger on the given jet and
|
---|
| 143 | /// returns the tagged PseudoJet if successful, or a PseudoJet==0 otherwise
|
---|
| 144 | /// (standard access is through operator()).
|
---|
| 145 | /// \param jet the PseudoJet to tag
|
---|
| 146 | virtual PseudoJet result(const PseudoJet & jet) const;
|
---|
| 147 |
|
---|
| 148 | // the type of the associated structure
|
---|
| 149 | typedef JHTopTaggerStructure StructureType;
|
---|
| 150 |
|
---|
| 151 | protected:
|
---|
| 152 | /// runs the Johns Hopkins decomposition procedure
|
---|
| 153 | std::vector<PseudoJet> _split_once(const PseudoJet & jet_to_split,
|
---|
| 154 | const PseudoJet & reference_jet) const;
|
---|
| 155 |
|
---|
| 156 | double _delta_p, _delta_r, _cos_theta_W_max, _mW;
|
---|
| 157 | static LimitedWarning _warnings_nonca;
|
---|
| 158 | };
|
---|
| 159 |
|
---|
| 160 |
|
---|
| 161 | //------------------------------------------------------------------------
|
---|
| 162 | /// @ingroup tools_taggers
|
---|
| 163 | /// \class JHTopTaggerStructure
|
---|
| 164 | /// the structure returned by the JHTopTagger transformer.
|
---|
| 165 | ///
|
---|
| 166 | /// See the JHTopTagger class description for the details of what
|
---|
| 167 | /// is inside this structure
|
---|
| 168 | ///
|
---|
| 169 | class JHTopTaggerStructure : public CompositeJetStructure, public TopTaggerBaseStructure {
|
---|
| 170 | public:
|
---|
| 171 | /// ctor with pieces initialisation
|
---|
| 172 | JHTopTaggerStructure(std::vector<PseudoJet> pieces_in,
|
---|
| 173 | const JetDefinition::Recombiner *recombiner = 0) :
|
---|
| 174 | CompositeJetStructure(pieces_in, recombiner), _cos_theta_w(0.0){}
|
---|
| 175 |
|
---|
| 176 | /// returns the W subjet
|
---|
| 177 | inline const PseudoJet & W() const{
|
---|
| 178 | return _pieces[0];
|
---|
| 179 | }
|
---|
| 180 |
|
---|
| 181 | /// returns the first W subjet (the harder)
|
---|
| 182 | inline PseudoJet W1() const{
|
---|
| 183 | assert(W().pieces().size()>0);
|
---|
| 184 | return W().pieces()[0];
|
---|
| 185 | }
|
---|
| 186 |
|
---|
| 187 | /// returns the second W subjet
|
---|
| 188 | inline PseudoJet W2() const{
|
---|
| 189 | assert(W().pieces().size()>1);
|
---|
| 190 | return W().pieces()[1];
|
---|
| 191 | }
|
---|
| 192 |
|
---|
| 193 | /// returns the non-W subjet
|
---|
| 194 | /// It will have 1 or 2 pieces depending on whether the tagger has
|
---|
| 195 | /// found 3 or 4 pieces
|
---|
| 196 | inline const PseudoJet & non_W() const{
|
---|
| 197 | return _pieces[1];
|
---|
| 198 | }
|
---|
| 199 |
|
---|
| 200 | /// returns the W helicity angle
|
---|
| 201 | inline double cos_theta_W() const {return _cos_theta_w;}
|
---|
| 202 |
|
---|
| 203 | // /// returns the original jet (before tagging)
|
---|
| 204 | // const PseudoJet & original() const {return _original_jet;}
|
---|
| 205 |
|
---|
| 206 |
|
---|
| 207 | protected:
|
---|
| 208 | double _cos_theta_w; ///< the W helicity angle
|
---|
| 209 | //PseudoJet _W; ///< the tagged W
|
---|
| 210 | //PseudoJet _non_W; ///< the remaining pieces
|
---|
| 211 | // PseudoJet _original_jet; ///< the original jet (before tagging)
|
---|
| 212 |
|
---|
| 213 | // allow the tagger to set these
|
---|
| 214 | friend class JHTopTagger;
|
---|
| 215 | };
|
---|
| 216 |
|
---|
| 217 |
|
---|
| 218 |
|
---|
| 219 | FASTJET_END_NAMESPACE
|
---|
| 220 |
|
---|
| 221 | #endif // __FASTJET_JH_TOP_TAGGER_HH__
|
---|
| 222 |
|
---|