1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/UnstableParticles.hh"
  4
  5namespace Rivet {
  6
  7
  8  /// @brief D0 -> pi, K ell nu_ell
  9  class BELLE_2006_I715430 : public Analysis {
 10  public:
 11
 12    /// Constructor
 13    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2006_I715430);
 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      // histos
 24      for (unsigned int ix=0; ix<2; ++ix) {
 25        book(_h[ix],"TMP/h_"+toString(ix+1), refData(1+ix, 1, 1));
 26      }
 27      book(_c,"TMP/nD");
 28    }
 29
 30    // Calculate the Q2 using mother and daugher meson
 31    double q2(const Particle& B, int mesonID) const {
 32      FourMomentum q = B.mom() - select(B.children(), Cuts::abspid==abs(mesonID))[0];
 33      return q*q;
 34    }
 35
 36    // Check for explicit decay into pdgids
 37    bool isSemileptonicDecay(const Particle& mother, vector<int> ids) const {
 38      // Trivial check to ignore any other decays but the one in question modulo photons
 39      const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
 40      if (children.size()!=ids.size()) return false;
 41      // Check for the explicit decay
 42      return all(ids, [&](int i){return count(children, hasPID(i))==1;});
 43    }
 44
 45    /// Perform the per-event analysis
 46    void analyze(const Event& event) {
 47      const double M0 = 1.86484, M02 = sqr(M0);
 48      const double m2[2] = {sqr(0.493677),sqr(0.13957039)};
 49      // Loop over D mesons
 50      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
 51        _c->fill();
 52        if (isSemileptonicDecay(p, {PID::PIMINUS, PID::POSITRON, PID::NU_E}) ||
 53            isSemileptonicDecay(p, {PID::PIPLUS , PID::ELECTRON, PID::NU_EBAR}) ) {
 54          double qq = q2(p, PID::PIMINUS);
 55          double pcm = sqrt(0.25/M02*(sqr(M02)+sqr(qq)+sqr(m2[1])-2.*qq*m2[1]-2.*M02*qq-2.*m2[1]*M02));
 56          _h[1]->fill(qq,1./pow(pcm,3));
 57        }
 58        else if(isSemileptonicDecay(p, {PID::KMINUS, PID::POSITRON, PID::NU_E}) ||
 59                isSemileptonicDecay(p, {PID::KPLUS , PID::ELECTRON, PID::NU_EBAR})) {
 60          double qq = q2(p, PID::KMINUS);
 61          double pcm = sqrt(0.25/M02*(sqr(M02)+sqr(qq)+sqr(m2[0])-2.*qq*m2[0]-2.*M02*qq-2.*m2[0]*M02));
 62          _h[0]->fill(qq,1./pow(pcm,3));
 63        }
 64      }
 65    }
 66
 67
 68    /// Normalise histograms etc., after the run
 69    void finalize() {
 70      const double GF      = 1.1663788e-5;
 71      const double CKM[2]  = {0.975,0.221};
 72      const double gamma   = 6.582119569e-25/4.103e-13;
 73      const double pre    = 24.*pow(M_PI,3)/sqr(GF)*gamma;
 74      for (unsigned int ix=0; ix<2; ++ix) {
 75        double fact = pre/sqr(CKM[ix]);
 76        Estimate1DPtr tmp;
 77        book(tmp,1+ix,1,1);
 78        scale(_h[ix],fact/ *_c);
 79        for (unsigned int iy=0; iy<_h[ix]->numBins(); ++iy) {
 80          double val = _h[ix]->bin(iy+1).sumW()/_h[ix]->bin(iy+1).xWidth();
 81          double err = _h[ix]->bin(iy+1).errW()/_h[ix]->bin(iy+1).xWidth();
 82          val = sqrt(val);
 83          err /= 2.*val ;
 84          tmp->bin(iy+1).set(val,err);
 85        }
 86      }
 87    }
 88
 89    /// @}
 90
 91
 92    /// @name Histograms
 93    /// @{
 94    Histo1DPtr _h[2];
 95    CounterPtr _c;
 96    /// @}
 97
 98
 99  };
100
101
102  RIVET_DECLARE_PLUGIN(BELLE_2006_I715430);
103
104}