Rivet analyses referenceBELLE_2020_I1785816Dalitz decay of $D^0\to K^-\pi^+\eta$Experiment: BELLE (KEKB) Inspire ID: 1785816 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $D^0\to K^-\pi^+\eta$ by BELLE. The data were read from the plots in the paper, and for many points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded. Source code: BELLE_2020_I1785816.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- pi+ eta
10 class BELLE_2020_I1785816 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2020_I1785816);
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_Kpi ,1,1,1);
33 book(_h_etapi,1,1,2);
34 book(_h_Keta ,1,1,3);
35 book(_dalitz, "dalitz",50,0.3,1.8,50,0.4,1.9);
36 }
37
38 /// Perform the per-event analysis
39 void analyze(const Event& event) {
40 static const map<PdgId,unsigned int> & mode = { {-321,1},{ 211,1}, {221,1}};
41 static const map<PdgId,unsigned int> & modeCC = { { 321,1},{-211,1}, {221,1}};
42 DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
43 // loop over particles
44 for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
45 int sign = 1;
46 if (D0.decaying()[ix].pid()>0 && D0.modeMatches(ix,3,mode)) {
47 sign=1;
48 }
49 else if (D0.decaying()[ix].pid()<0 && D0.modeMatches(ix,3,modeCC)) {
50 sign=-1;
51 }
52 else
53 continue;
54 const Particles & eta= D0.decayProducts()[ix].at(221);
55 const Particles & Km = D0.decayProducts()[ix].at(-sign*321);
56 const Particles & pip= D0.decayProducts()[ix].at( sign*211);
57 double metapi = (eta[0].momentum()+pip[0].momentum()).mass2();
58 double metaK = (eta[0].momentum()+ Km[0].momentum()).mass2();
59 double mKpi = ( Km[0].momentum()+pip[0].momentum()).mass2();
60 _dalitz ->fill(mKpi,metapi);
61 _h_etapi->fill(metapi);
62 _h_Keta ->fill(metaK );
63 _h_Kpi ->fill(mKpi);
64 }
65 }
66
67
68 /// Normalise histograms etc., after the run
69 void finalize() {
70 normalize(_h_Kpi );
71 normalize(_h_etapi);
72 normalize(_h_Keta );
73 normalize(_dalitz );
74 }
75
76 /// @}
77
78
79 /// @name Histograms
80 /// @{
81 Histo1DPtr _h_Kpi,_h_etapi,_h_Keta;
82 Histo2DPtr _dalitz;
83 /// @}
84
85
86 };
87
88
89 RIVET_DECLARE_PLUGIN(BELLE_2020_I1785816);
90
91}
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