Rivet analyses referenceBESIII_2012_I1187787Dalitz plot analysis of $\eta_c\to K^0_SK^\pm\pi^\mp$Experiment: BESIII (BEPC) Inspire ID: 1187787 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decays $\eta_c\to K^0_SK^\pm\pi^\mp$ by BESIII. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded. Source code: BESIII_2012_I1187787.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4#include "Rivet/Projections/DecayedParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief eta_c -> KS0 K+-pi-+
10 class BESIII_2012_I1187787 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2012_I1187787);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 UnstableParticles ufs = UnstableParticles(Cuts::pid==441);
24 declare(ufs, "UFS");
25 DecayedParticles etac(ufs);
26 etac.addStable(PID::PI0);
27 etac.addStable(PID::K0S);
28 etac.addStable(PID::ETA);
29 etac.addStable(PID::ETAPRIME);
30 declare(etac, "etac");
31 // histograms
32 book(_h_K0pip,1,1,1);
33 book(_h_K0Kp ,1,1,2);
34 book(_h_Kppip,1,1,3);
35 book(_dalitz, "dalitz",50,0.,8.,50,0.,8.);
36 }
37
38
39 /// Perform the per-event analysis
40 void analyze(const Event& event) {
41 static const map<PdgId,unsigned int> & mode = { { 321,1}, {310,1}, {-211,1} };
42 static const map<PdgId,unsigned int> & modeCC = { {-321,1}, {310,1}, { 211,1} };
43 DecayedParticles etac = apply<DecayedParticles>(event, "etac");
44 // loop over particles
45 for(unsigned int ix=0;ix<etac.decaying().size();++ix) {
46 int sign=1;
47 if(etac.modeMatches(ix,3,mode)) {
48 sign=1;
49 }
50 else if(etac.modeMatches(ix,3,modeCC)) {
51 sign=-1;
52 }
53 else
54 continue;
55 const Particle & KS0 = etac.decayProducts()[ix].at( 310)[0];
56 const Particle & pim = etac.decayProducts()[ix].at(-sign*211)[0];
57 const Particle & Kp = etac.decayProducts()[ix].at( sign*321)[0];
58 double mplus = (Kp .momentum() + pim.momentum()).mass2();
59 double mminus = (KS0.momentum() + pim.momentum()).mass2();
60 double mKK = (Kp .momentum() + KS0.momentum()).mass2();
61 _h_K0Kp ->fill(sqrt(mKK ));
62 _h_Kppip->fill(sqrt(mplus ));
63 _h_K0pip->fill(sqrt(mminus));
64 _dalitz->fill(mplus,mminus);
65 }
66 }
67
68
69 /// Normalise histograms etc., after the run
70 void finalize() {
71 normalize(_h_Kppip);
72 normalize(_h_K0pip);
73 normalize(_h_K0Kp );
74 normalize(_dalitz );
75 }
76
77 /// @}
78
79
80 /// @name Histograms
81 /// @{
82 Histo1DPtr _h_Kppip,_h_K0pip,_h_K0Kp;
83 Histo2DPtr _dalitz;
84 /// @}
85
86
87 };
88
89
90 RIVET_DECLARE_PLUGIN(BESIII_2012_I1187787);
91
92}
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