Rivet analyses referenceBESIII_2018_I1662665$\pi^0\eta$ mass distribution in $D^0\to\pi^0\eta\eta$Experiment: BESIII (BEPC) Inspire ID: 1662665 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the $\pi^0\eta$ mass distribution in $D^0\to\pi^0\eta\eta$ by BES. The data were read from the plots in the paper. It is also not clear that any resolution effects have been unfolded. Source code: BESIII_2018_I1662665.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 -> eta eta pi0
10 class BESIII_2018_I1662665 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2018_I1662665);
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_pieta,1,1,1);
33 book(_dalitz,"dalitz",50.,0.4,1.6,50,0.4,1.8);
34 }
35
36 /// Perform the per-event analysis
37 void analyze(const Event& event) {
38 // define the decay mode
39 static const map<PdgId,unsigned int> & mode = { { 221,2}, {111,1}};
40 DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
41 // loop over particles
42 for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
43 if ( ! D0.modeMatches(ix,3,mode)) continue;
44 const Particles & eta = D0.decayProducts()[ix].at(221);
45 const Particles & pi0 = D0.decayProducts()[ix].at(111);
46 double m1 = (eta[0].momentum()+pi0[0].momentum()).mass2();
47 double m2 = (eta[1].momentum()+pi0[0].momentum()).mass2();
48 if(m1>m2) swap(m1,m2);
49 _dalitz->fill(m1,m2);
50 _h_pieta->fill(sqrt(m1));
51 _h_pieta->fill(sqrt(m2));
52 }
53 }
54
55
56 /// Normalise histograms etc., after the run
57 void finalize() {
58 normalize(_h_pieta);
59 normalize(_dalitz);
60 }
61
62 /// @}
63
64
65 /// @name Histograms
66 /// @{
67 Histo1DPtr _h_pieta;
68 Histo2DPtr _dalitz;
69 /// @}
70
71
72 };
73
74
75 RIVET_DECLARE_PLUGIN(BESIII_2018_I1662665);
76
77}
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