1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief B0 -> pi/rho ell+ nu_ell
 9  class CLEOII_2003_I616827 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_2003_I616827);
14
15
16    /// @name Analysis methods
17    /// @{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // Initialise and register projections
22      declare(UnstableParticles(Cuts::abspid==511), "UFS");
23      for (unsigned int ix=0; ix<2; ++ix) {
24        book(_h[ix], 1+ix, 1, 1);
25      }
26      book(_c,"TMP/nB");
27    }
28
29    // Calculate the Q2 using mother and daugher meson
30    double q2(const Particle& B, int mesonID) {
31      FourMomentum q = B.mom() - 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 B0bar Mesons
47      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::B0BAR)) {
48        _c->fill();
49        if (isSemileptonicDecay(p, {PID::PIPLUS, PID::ELECTRON, PID::NU_EBAR}) ||
50            isSemileptonicDecay(p, {PID::PIPLUS, PID::MUON,     PID::NU_MUBAR})) {
51          _h[0]->fill(q2(p, PID::PIPLUS));
52        }
53        if (isSemileptonicDecay(p, {PID::RHOPLUS, PID::ELECTRON, PID::NU_EBAR}) ||
54            isSemileptonicDecay(p, {PID::RHOPLUS, PID::MUON,     PID::NU_MUBAR})) {
55          _h[1]->fill(q2(p, PID::RHOPLUS));
56        }
57      }
58    }
59
60
61    /// Normalise histograms etc., after the run
62    void finalize() {
63      // 1e4 for q0-4 in BR and 0.5 as both e/mu modes
64      scale(_h, 0.5*1e4/ *_c);
65    }
66
67    /// @}
68
69
70    /// @name Histograms
71    /// @{
72    Histo1DPtr _h[2];
73    CounterPtr _c;
74    /// @}
75
76
77  };
78
79
80  RIVET_DECLARE_PLUGIN(CLEOII_2003_I616827);
81
82}