1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/UnstableParticles.hh"
  4
  5namespace Rivet {
  6
  7
  8  /// @brief B -> D semi-leptonic
  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      book(_wB0   ,"/TMP/wB0"   );
 32      book(_wBPlus,"/TMP/wBPlus");
 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    // Calculate the recoil w using mother and daugher meson
 45    double recoilW(const Particle& B, int mesonID) {
 46      // TODO why does that not work with const?
 47      Particle D = select(B.children(), Cuts::pid==mesonID)[0];
 48      FourMomentum q = B.mom() - D.mom();
 49      return (B.mom()*B.mom() + D.mom()*D.mom() - q*q )/ (2. * sqrt(B.mom()*B.mom()) * sqrt(D.mom()*D.mom()) );
 50    }
 51
 52
 53    /// Perform the per-event analysis
 54    void analyze(const Event& event) {
 55      // Get B0 Mesons
 56      for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::B0)) {
 57        _wB0->fill();
 58        if (isSemileptonicDecay(p, {PID::DMINUS,PID::POSITRON,PID::NU_E})) _h_B_Denu->fill( recoilW(p, PID::DMINUS));
 59        if (isSemileptonicDecay(p, {PID::DMINUS,PID::ANTIMUON,PID::NU_MU})) _h_B_Dmunu->fill(recoilW(p, PID::DMINUS));
 60      }
 61      // Get B+ Mesons
 62      for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::BPLUS)) {
 63        _wBPlus->fill();
 64        if (isSemileptonicDecay(p, {PID::D0BAR,PID::POSITRON,PID::NU_E})) _h_B_Deplusnu->fill( recoilW(p, PID::D0BAR));
 65        if (isSemileptonicDecay(p, {PID::D0BAR,PID::ANTIMUON,PID::NU_MU})) _h_B_Dmuplusnu->fill(recoilW(p, PID::D0BAR));
 66      }
 67    }
 68
 69
 70    /// Normalise histograms etc., after the run
 71    void finalize() {
 72      const double hbar=6.582119569e-25;
 73      const double t0=1.519e-12,tPlus=1.638e-12;
 74      scale(_h_B_Denu     ,1e15*hbar/t0   / *_wB0);     
 75      scale(_h_B_Dmunu    ,1e15*hbar/t0   / *_wB0);    
 76      scale(_h_B_Deplusnu ,1e15*hbar/tPlus/ *_wBPlus); 
 77      scale(_h_B_Dmuplusnu,1e15*hbar/tPlus/ *_wBPlus);
 78    }
 79
 80    /// @}
 81
 82
 83  private:
 84
 85
 86    /// @name Histograms
 87    /// @{
 88    CounterPtr _wB0,_wBPlus;
 89    Histo1DPtr _h_B_Denu;
 90    Histo1DPtr _h_B_Dmunu;
 91    Histo1DPtr _h_B_Deplusnu;
 92    Histo1DPtr _h_B_Dmuplusnu;
 93    /// @}
 94
 95
 96  };
 97
 98
 99  RIVET_DECLARE_PLUGIN(BELLE_2015_I1397632);
100
101
102}