1 #ifndef __SISCONEPLUGIN_HH__
2 #define __SISCONEPLUGIN_HH__
4 #include "SISConeBasePlugin.hh"
6 // forward declaration of the siscone classes we'll need
12 namespace fastjet { // defined in fastjet/internal/base.hh
14 //----------------------------------------------------------------------
16 /// SISConePlugin is a plugin for fastjet (v2.1 upwards) that provides
17 /// an interface to the seedless infrared safe cone jet finder by
18 /// Gregory Soyez and Gavin Salam.
20 /// SISCone uses geometrical techniques to exhaustively consider all
21 /// possible distinct cones. It then finds out which ones are stable
22 /// and sends the result to the Tevatron Run-II type split-merge
23 /// procedure for overlapping cones.
25 /// Four parameters govern the "physics" of the algorithm:
27 /// - the cone_radius (this should be self-explanatory!)
29 /// - the overlap_threshold is the parameter which dictates how much
30 /// two jets must overlap (pt_overlap/min(pt1,pt2)) if they are to be
33 /// - Not all particles are in stable cones in the first round of
34 /// searching for stable cones; one can therefore optionally have the
35 /// the jet finder carry out additional passes of searching for
36 /// stable cones among particles that were in no stable cone in
37 /// previous passes --- the maximum number of passes carried out is
38 /// n_pass_max. If this is zero then additional passes are carried
39 /// out until no new stable cones are found.
41 /// - Protojet ptmin: protojets that are below this ptmin
42 /// (default = 0) are discarded before each iteration of the
45 /// One parameter governs some internal algorithmic shortcuts:
47 /// - if "caching" is turned on then the last event clustered by
48 /// siscone is stored -- if the current event is identical and the
49 /// cone_radius and n_pass_mass are identical, then the only part of
50 /// the clustering that needs to be rerun is the split-merge part,
51 /// leading to significant speed gains; there is a small (O(N) storage
52 /// and speed) penalty for caching, so it should be kept off
53 /// (default) if only a single overlap_threshold is used.
55 /// The final jets can be accessed by requestion the
56 /// inclusive_jets(...) from the ClusterSequence object. Note that
57 /// these PseudoJets have their user_index() set to the index of the
58 /// pass in which they were found (first pass = 0). NB: This does not
59 /// currently work for jets that consist of a single particle.
61 /// For further information on the details of the algorithm see the
62 /// SISCone paper, arXiv:0704.0292 [JHEP 0705:086,2007].
64 /// For documentation about the implementation, see the
65 /// siscone/doc/html/index.html file.
67 class SISConePlugin : public SISConeBasePlugin{
70 /// enum for the different split-merge scale choices;
71 /// Note that order _must_ be the same as in siscone
72 enum SplitMergeScale {SM_pt, ///< transverse momentum (E-scheme), IR unsafe
73 SM_Et, ///< transverse energy (E-scheme), not long. boost invariant
74 ///< original run-II choice [may not be implemented]
75 SM_mt, ///< transverse mass (E-scheme), IR safe except
76 ///< in decays of two identical narrow heavy particles
77 SM_pttilde ///< pt-scheme pt = \sum_{i in jet} |p_{ti}|, should
78 ///< be IR safe in all cases
82 /// Main constructor for the SISCone Plugin class.
84 /// Note: wrt version prior to 2.4 this constructor differs in that a
85 /// the default value has been removed for overlap_threshold. The
86 /// former has been removed because the old default of 0.5 was found
87 /// to be unsuitable in high-noise environments; so the user should
88 /// now explicitly think about the value for this -- we recommend
91 SISConePlugin (double cone_radius,
92 double overlap_threshold,
94 double protojet_ptmin = 0.0,
96 SplitMergeScale split_merge_scale = SM_pttilde,
97 double split_merge_stopping_scale = 0.0){
98 _cone_radius = cone_radius;
99 _overlap_threshold = overlap_threshold;
100 _n_pass_max = n_pass_max;
101 _protojet_ptmin = protojet_ptmin;
103 _split_merge_scale = split_merge_scale;
104 _split_merge_stopping_scale = split_merge_stopping_scale;
105 _ghost_sep_scale = 0.0;
106 _use_pt_weighted_splitting = false;}
109 /// Backwards compatible constructor for the SISCone Plugin class
110 SISConePlugin (double cone_radius,
111 double overlap_threshold,
113 double protojet_ptmin,
115 bool split_merge_on_transverse_mass){
116 _cone_radius = cone_radius;
117 _overlap_threshold = overlap_threshold;
118 _n_pass_max = n_pass_max;
119 _protojet_ptmin = protojet_ptmin;
121 _split_merge_stopping_scale = 0.0;
122 _split_merge_scale = split_merge_on_transverse_mass ? SM_mt : SM_pttilde;
123 _ghost_sep_scale = 0.0;}
125 /// backwards compatible constructor for the SISCone Plugin class
126 /// (avoid using this in future).
127 SISConePlugin (double cone_radius,
128 double overlap_threshold,
131 _cone_radius = cone_radius;
132 _overlap_threshold = overlap_threshold;
133 _n_pass_max = n_pass_max;
134 _protojet_ptmin = 0.0;
136 _split_merge_scale = SM_mt;
137 _split_merge_stopping_scale = 0.0;
138 _ghost_sep_scale = 0.0;
139 _use_pt_weighted_splitting = false;}
141 /// minimum pt for a protojet to be considered in the split-merge step
143 double protojet_ptmin () const {return _protojet_ptmin ;}
145 /// return the scale to be passed to SISCone as the protojet_ptmin
146 /// -- if we have a ghost separation scale that is above the
147 /// protojet_ptmin, then the ghost_separation_scale becomes the
148 /// relevant one to use here
149 double protojet_or_ghost_ptmin () const {return std::max(_protojet_ptmin,
152 /// indicates scale used in split-merge
153 SplitMergeScale split_merge_scale() const {return _split_merge_scale;}
154 /// sets scale used in split-merge
155 void set_split_merge_scale(SplitMergeScale sms) {_split_merge_scale = sms;}
157 /// indicates whether the split-merge orders on transverse mass or not.
158 /// retained for backwards compatibility with 2.1.0b3
159 bool split_merge_on_transverse_mass() const {return _split_merge_scale == SM_mt ;}
160 void set_split_merge_on_transverse_mass(bool val) {
161 _split_merge_scale = val ? SM_mt : SM_pt;}
163 /// indicates whether the split-merge orders on transverse mass or not.
164 /// retained for backwards compatibility with 2.1.0b3
165 bool split_merge_use_pt_weighted_splitting() const {return _use_pt_weighted_splitting;}
166 void set_split_merge_use_pt_weighted_splitting(bool val) {
167 _use_pt_weighted_splitting = val;}
169 // the things that are required by base class
170 virtual std::string description () const;
171 virtual void run_clustering(ClusterSequence &) const ;
174 virtual void reset_stored_plugin() const;
177 double _protojet_ptmin;
178 SplitMergeScale _split_merge_scale;
180 bool _use_pt_weighted_splitting;
182 // part needed for the cache
183 // variables for caching the results and the input
184 static std::auto_ptr<SISConePlugin > stored_plugin;
185 static std::auto_ptr<std::vector<PseudoJet> > stored_particles;
186 static std::auto_ptr<siscone::Csiscone > stored_siscone;
190 //======================================================================
191 /// Class that provides extra information about a SISCone clustering
192 class SISConeExtras : public SISConeBaseExtras {
195 // it just initialises the pass information
196 SISConeExtras(int nparticles)
197 : SISConeBaseExtras(nparticles){}
199 /// access to the siscone jet def plugin (more convenient than
200 /// getting it from the original jet definition, because here it's
201 /// directly of the right type (rather than the base type)
202 const SISConePlugin* jet_def_plugin() const {
203 return dynamic_cast<const SISConePlugin*>(_jet_def_plugin);
207 // let us be written to by SISConePlugin
208 friend class SISConePlugin;
211 } // fastjet namespace
213 #endif // __SISCONEPLUGIN_HH__