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BABAR_2007_I1091435

$D^0\to K^- e^+\nu_e$ $q^2$ spectrum
Experiment: BABAR (PEP-II)
Inspire ID: 1091435
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D76 (2007) 052005
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing D0

Measurement of the $q^2$ spectrum in the decay $D^0\to K^- e^+\nu_e$ by BaBar.

Source code: BABAR_2007_I1091435.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief q^2 in D0 -> K- e+ nu_e decays
 9  class BABAR_2007_I1091435 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I1091435);
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      declare(UnstableParticles(), "UFS");
24
25      // Book histograms
26      book(_h_q2 ,1, 1, 1);
27    }
28
29    // Calculate the Q2 using mother and daugher meson
30    double q2(const Particle& B, int mesonID) {
31      FourMomentum q = B.mom() - filter_select(B.children(), Cuts::pid==mesonID)[0];
32      return q*q;
33    }
34
35    // Check for explicit decay into pdgids
36    bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
37      // Trivial check to ignore any other decays but the one in question modulo photons
38      const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
39      if (children.size()!=ids.size()) return false;
40      // Check for the explicit decay
41      return all(ids, [&](int i){return count(children, hasPID(i))==1;});
42    }
43
44    /// Perform the per-event analysis
45    void analyze(const Event& event) {
46      // Loop over B0 mesons 
47      for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::D0)) {
48        if (isSemileptonicDecay(p, {PID::KMINUS, PID::POSITRON, PID::NU_E}) ) {
49	  _h_q2->fill(q2(p, PID::KMINUS));
50        }
51      }
52    }
53
54
55    /// Normalise histograms etc., after the run
56    void finalize() {
57      normalize(_h_q2, 1.);
58    }
59
60    ///@}
61
62
63    /// @name Histograms
64    ///@{
65    Histo1DPtr _h_q2;
66    ///@}
67
68
69  };
70
71
72  RIVET_DECLARE_PLUGIN(BABAR_2007_I1091435);
73
74}