Rivet analyses referenceBESIII_2020_I1799437Dalitz plot analysis of D0→K0SK+K−Experiment: BESIII (BEPC) Inspire ID: 1799437 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of Kinematic distributions in the decay D0→K0SK+K− by BES. The data were read from the plots in the paper. Resolution/acceptance effects have been not unfolded. Given the agreement with the model in the paper this analysis should only be used for qualitative studies. Source code: BESIII_2020_I1799437.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 D0 -> K_S0 K+ K-
10 class BESIII_2020_I1799437 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1799437);
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::abspid==421);
24 declare(ufs, "UFS");
25 DecayedParticles D0(ufs);
26 D0.addStable(PID::PI0);
27 D0.addStable(PID::K0S);
28 D0.addStable(PID::ETA);
29 D0.addStable(PID::ETAPRIME);
30 declare(D0, "D0");
31 // Histograms
32 book(_h_K0Km,1,1,3);
33 book(_h_K0Kp,1,1,2);
34 book(_h_KpKm,1,1,1);
35 book(_dalitz, "dalitz",50,0.9,1.9,50,0.9,1.9);
36 }
37
38 /// Perform the per-event analysis
39 void analyze(const Event& event) {
40 static const map<PdgId,unsigned int> & mode = { { 321,1},{-321,1}, { 310,1}};
41 DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
42 // loop over particles
43 for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
44 if( ! D0.modeMatches(ix,3,mode) ) continue;
45 int sign = D0.decaying()[ix].pid()/421;
46 const Particles & K0 = D0.decayProducts()[ix].at(310);
47 const Particles & Kp = D0.decayProducts()[ix].at( sign*321);
48 const Particles & Km = D0.decayProducts()[ix].at(-sign*321);
49 double mminus = (Km[0].momentum()+K0[0].momentum() ).mass2();
50 double mplus = (Kp[0].momentum()+K0[0].momentum() ).mass2();
51 double mKK = (Kp[0].momentum()+Km[0].momentum()).mass2();
52 _h_K0Kp->fill(mplus);
53 _h_K0Km->fill(mminus);
54 _h_KpKm->fill(mKK);
55 _dalitz->fill(mKK,mplus);
56 }
57 }
58
59
60 /// Normalise histograms etc., after the run
61 void finalize() {
62 normalize(_h_K0Km);
63 normalize(_h_K0Kp);
64 normalize(_h_KpKm);
65 normalize(_dalitz);
66 }
67
68 /// @}
69
70
71 /// @name Histograms
72 /// @{
73 Histo1DPtr _h_K0Km,_h_KpKm,_h_K0Kp;
74 Histo2DPtr _dalitz;
75 /// @}
76
77
78 };
79
80
81 RIVET_DECLARE_PLUGIN(BESIII_2020_I1799437);
82
83}
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