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BELLE_2021_I1867474

Mass distributions in $D^0\to\pi^+\pi^-\eta$ and $D^0\to K^+K^-\eta$
Experiment: BELLE (KEKB)
Inspire ID: 1867474
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • JHEP 09 (2021) 075
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing D0 mesons

Measurement of the mass distributions in the decays $D^0\to\pi^+\pi^-\eta$ and $D^0\to K^+K^-\eta$ 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_2021_I1867474.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 -> pi+pi-eta, K+K-eta
10  class BELLE_2021_I1867474 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2021_I1867474);
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      for (unsigned int ix=0; ix<2; ++ix) {
33        for (unsigned int iy=0; iy<3; ++iy) {
34          book(_h[ix][iy],1+ix,1,1+iy);
35        }
36      }
37    }
38
39
40    /// Perform the per-event analysis
41    void analyze(const Event& event) {
42      DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
43      // loop over particles
44      for (unsigned int ix=0; ix<D0.decaying().size(); ++ix) {
45        unsigned int imode=0;
46        if       (D0.modeMatches(ix,3,mode1)) imode=0;
47        else if  (D0.modeMatches(ix,3,mode2)) imode=1;
48        else continue;
49        int sign = D0.decaying()[ix].pid()/D0.decaying()[ix].abspid();
50        int im = 211+imode*110;
51        const Particle& eta = D0.decayProducts()[ix].at(221)[0];
52        const Particle& pim = D0.decayProducts()[ix].at(-sign*im)[0];
53        const Particle& pip = D0.decayProducts()[ix].at( sign*im)[0];
54        _h[imode][0]->fill((pip.mom()+pim.mom()).mass2());
55        _h[imode][1]->fill((pim.mom()+eta.mom()).mass2());
56        _h[imode][2]->fill((pip.mom()+eta.mom()).mass2());
57      }
58    }
59
60
61    /// Normalise histograms etc., after the run
62    void finalize() {
63      for (unsigned int ix=0; ix<2; ++ix) {
64        normalize(_h[ix], 1.0, false);
65      }
66    }
67
68    /// @}
69
70
71    /// @name Histograms
72    /// @{
73    Histo1DPtr _h[2][3];
74    const map<PdgId,unsigned int> mode1 = { { 211,1},{-211,1}, {221,1}};
75    const map<PdgId,unsigned int> mode2 = { { 321,1},{-321,1}, {221,1}};
76    /// @}
77
78
79  };
80
81
82  RIVET_DECLARE_PLUGIN(BELLE_2021_I1867474);
83
84}