1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/UnstableParticles.hh"
  4#include "Rivet/Projections/DecayedParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief D+ -> K- pi+ e+ nu_e
 10  class BABAR_2010_I879997 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2010_I879997);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22
 23      // Initialise and register projections
 24      UnstableParticles ufs = UnstableParticles(Cuts::pid==411);
 25      declare(ufs, "UFS");
 26      DecayedParticles DP(ufs);
 27      DP.addStable(PID::PI0);
 28      DP.addStable(PID::K0S);
 29      DP.addStable(PID::ETA);
 30      DP.addStable(PID::ETAPRIME);
 31      declare(DP, "DP");
 32
 33      // Book histograms
 34      for (size_t ix=0; ix<5; ++ix) {
 35        book(_h[ix],1,1,1+ix);
 36      }
 37      const vector<double> bins{0.,0.8,0.9,1.,1.6};
 38      for (size_t ix=0; ix<4; ++ix) {
 39        book(_b[ix], bins);
 40        for (auto& b : _b[ix]->bins()) {
 41          book(b, 1+b.index(), 1, 1+ix);
 42        }
 43      }
 44    }
 45
 46
 47    /// Perform the per-event analysis
 48    void analyze(const Event& event) {
 49      static const map<PdgId,unsigned int> & mode = { { -321,1}, { 211,1}, {-11,1}, { 12,1}};
 50      DecayedParticles DP = apply<DecayedParticles>(event, "DP");
 51      // loop over particles
 52      for (unsigned int ix=0;ix<DP.decaying().size();++ix) {
 53        if ( !DP.modeMatches(ix,4,mode) ) continue;
 54       	const Particle & Km = DP.decayProducts()[ix].at(-321)[0];
 55       	const Particle & pip= DP.decayProducts()[ix].at( 211)[0];
 56       	const Particle & ep = DP.decayProducts()[ix].at( -11)[0];
 57       	const Particle & nue= DP.decayProducts()[ix].at(  12)[0];
 58        FourMomentum pKstar = Km.momentum()+pip.momentum();
 59        double mKpi = pKstar.mass();
 60        _h[4]->fill(mKpi);
 61        FourMomentum qq = DP.decaying()[ix].momentum()-pKstar;
 62        double q2 = qq.mass2();
 63        _h[0]->fill(q2);
 64        _b[0]->fill(mKpi,q2);
 65        // boost momenta to DP rest frame
 66        LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(DP.decaying()[ix].momentum().betaVec());
 67        FourMomentum pKS = boost.transform(pKstar);
 68        Matrix3 ptoz(-pKS.p3().unit(), Vector3(0,0,1));
 69        boost.preMult(ptoz);
 70        // the momenta in frane to W along z
 71        FourMomentum pD  = boost.transform(DP.decaying()[ix].momentum());
 72        FourMomentum pK  = boost.transform(Km .momentum());
 73        FourMomentum ppi = boost.transform(pip.momentum());
 74        FourMomentum pe  = boost.transform(ep .momentum());
 75        FourMomentum pnu = boost.transform(nue.momentum());
 76        pKstar = pK+ppi;
 77        qq = pD-pKstar;
 78        LorentzTransform boostK = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
 79      	Vector3 axisK = boostK.transform(pK).p3().unit();
 80        double cosK = axisK.dot(pKstar.p3().unit());
 81      	_h[2]->fill(cosK);
 82      	_b[2]->fill(mKpi,cosK);
 83      	LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta(qq.betaVec());
 84      	Vector3 axisE = boostW.transform(pe).p3().unit();
 85        double cosE = axisE.dot(qq.p3().unit());
 86      	_h[3]->fill(cosE);
 87        _b[3]->fill(mKpi,cosE);
 88      	axisK.setZ(0.);
 89      	axisE.setZ(0.);
 90      	double chi = atan2(axisE.cross(axisK).dot(qq.p3().unit()), axisE.dot(axisK));
 91      	_h[1]->fill(chi);
 92        _b[1]->fill(mKpi, chi);
 93      }
 94    }
 95
 96
 97    /// Normalise histograms etc., after the run
 98    void finalize() {
 99      normalize(_h);
100      normalize(_b);
101    }
102
103    /// @}
104
105
106    /// @name Histograms
107    /// @{
108    Histo1DPtr _h[5];
109    Histo1DGroupPtr _b[4];
110    /// @}
111
112
113  };
114
115
116  RIVET_DECLARE_PLUGIN(BABAR_2010_I879997);
117
118}