1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief D -> pi,K semi-leptonic q^2
 9  class CLEO_2004_I654843 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_2004_I654843);
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==PID::D0), "UFS");
23      // histograms
24      book(_h_q2_D0_K ,1,1,1);
25      book(_h_q2_D0_pi,1,1,2);
26    }
27
28    // Calculate the Q2 using mother and daugher meson
29    double q2(const Particle& B, int mesonID) {
30      FourMomentum q = B.mom() - select(B.children(), Cuts::abspid==abs(mesonID))[0];
31      return q*q;
32    }
33
34    // Check for explicit decay into pdgids
35    bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
36      // Trivial check to ignore any other decays but the one in question modulo photons
37      const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
38      if (children.size()!=ids.size()) return false;
39      // Check for the explicit decay
40      return all(ids, [&](int i){return count(children, hasPID(i))==1;});
41    }
42
43    /// Perform the per-event analysis
44    void analyze(const Event& event) {
45      // Loop over D mesons 
46      for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
47	if(isSemileptonicDecay(p, {PID::PIMINUS, PID::POSITRON, PID::NU_E}) ||
48	   isSemileptonicDecay(p, {PID::PIPLUS , PID::ELECTRON, PID::NU_EBAR}) )
49	  _h_q2_D0_pi->fill(q2(p, PID::PIMINUS));
50	else if(isSemileptonicDecay(p, {PID::KMINUS, PID::POSITRON, PID::NU_E}) ||
51		isSemileptonicDecay(p, {PID::KPLUS , PID::ELECTRON, PID::NU_EBAR}))
52	  _h_q2_D0_K ->fill(q2(p, PID::KMINUS));
53      }
54    }
55
56
57    /// Normalise histograms etc., after the run
58    void finalize() {
59      normalize(_h_q2_D0_K );
60      normalize(_h_q2_D0_pi);
61    }
62
63    /// @}
64
65
66    /// @name Histograms
67    /// @{
68    Histo1DPtr  _h_q2_D0_K, _h_q2_D0_pi;
69    CounterPtr _nD0,_nDp;
70    /// @}
71
72
73  };
74
75
76  RIVET_DECLARE_PLUGIN(CLEO_2004_I654843);
77
78}