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BELLE_2015_I1397632

Exclusive semileptonic $B$ to $D$ decays.
Experiment: BELLE (KEKB)
Inspire ID: 1397632
Status: VALIDATED
Authors:
  • Holger Schulz
No references listed
Beams: * *
Beam energies: ANY
Run details:
  • Events with $b$-decays, either particle guns or collisions.

Implementation of Lorentz invariant recoil w distributions for semileptonic B decays

Source code: BELLE_2015_I1397632.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief Add a short analysis description here
 9  class BELLE_2015_I1397632 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2015_I1397632);
14
15
16    /// @name Analysis methods
17    //@{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21
22      // Initialise and register projections
23
24      declare(UnstableParticles(), "UFS");
25
26      // Book histograms
27      book(_h_B_Denu,      1, 1, 1);
28      book(_h_B_Dmunu,     1, 1, 2);
29      book(_h_B_Deplusnu,  2, 1, 1);
30      book(_h_B_Dmuplusnu, 2, 1, 2);
31    }
32
33    // Check for explicit decay into pdgids
34    bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
35      // Trivial check to ignore any other decays but the one in question modulo photons
36      const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
37      if (children.size()!=ids.size()) return false;
38      // Check for the explicit decay
39      return all(ids, [&](int i){return count(children, hasPID(i))==1;});
40    }
41    
42    // Calculate the recoil w using mother and daugher meson
43    double recoilW(const Particle& B, int mesonID) {
44      // TODO why does that not work with const?
45      Particle D = filter_select(B.children(), Cuts::pid==mesonID)[0];
46      FourMomentum q = B.mom() - D.mom();
47      return (B.mom()*B.mom() + D.mom()*D.mom() - q*q )/ (2. * sqrt(B.mom()*B.mom()) * sqrt(D.mom()*D.mom()) );
48    }
49
50
51    /// Perform the per-event analysis
52    void analyze(const Event& event) {
53      // Get B0 Mesons
54      for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::B0)) {
55        if (isSemileptonicDecay(p, {PID::DMINUS,PID::POSITRON,PID::NU_E})) _h_B_Denu->fill( recoilW(p, PID::DMINUS));
56        if (isSemileptonicDecay(p, {PID::DMINUS,PID::ANTIMUON,PID::NU_MU})) _h_B_Dmunu->fill(recoilW(p, PID::DMINUS));
57      }
58      // Get B+ Mesons
59      for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::BPLUS)) {
60        if (isSemileptonicDecay(p, {PID::D0BAR,PID::POSITRON,PID::NU_E})) _h_B_Deplusnu->fill( recoilW(p, PID::D0BAR));
61        if (isSemileptonicDecay(p, {PID::D0BAR,PID::ANTIMUON,PID::NU_MU})) _h_B_Dmuplusnu->fill(recoilW(p, PID::D0BAR));
62      }
63    }
64
65
66    /// Normalise histograms etc., after the run
67    void finalize() {
68
69      normalize(_h_B_Denu);     
70      normalize(_h_B_Dmunu);    
71      normalize(_h_B_Deplusnu); 
72      normalize(_h_B_Dmuplusnu);
73
74    }
75
76    //@}
77
78
79  private:
80
81
82    /// @name Histograms
83    //@{
84    Histo1DPtr _h_B_Denu;
85    Histo1DPtr _h_B_Dmunu;
86    Histo1DPtr _h_B_Deplusnu;
87    Histo1DPtr _h_B_Dmuplusnu;
88    //@}
89
90
91  };
92
93
94  // The hook for the plugin system
95  RIVET_DECLARE_PLUGIN(BELLE_2015_I1397632);
96
97
98}