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 B -> K pi pi
 10  class BABAR_2004_I626730 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2004_I626730);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      // Initialise and register projections
 23      UnstableParticles ufs = UnstableParticles(Cuts::abspid==521);
 24      declare(ufs, "UFS");
 25      DecayedParticles BP(ufs);
 26      BP.addStable(PID::K0S);
 27      declare(BP, "BP");
 28      for(unsigned int ix=0; ix<3; ++ix) {
 29	book(_h_mass2[ix],2,1,1+ix);
 30	book(_h_angle[ix],2,2,1+ix);
 31	if(ix==2) continue;
 32	book(_h_mass [ix],1,1,1+ix);
 33      }
 34    }
 35
 36
 37    /// Perform the per-event analysis
 38    void analyze(const Event& event) {
 39      static const map<PdgId,unsigned int> & mode   = { { 321,1}, { 211,1}, {-211,1}};
 40      static const map<PdgId,unsigned int> & modeCC = { {-321,1}, { 211,1}, {-211,1}};
 41      DecayedParticles BP = apply<DecayedParticles>(event, "BP");
 42      // loop over particles
 43      for(unsigned int ix=0;ix<BP.decaying().size();++ix) {
 44      	int sign = BP.decaying()[ix].pid()>0 ? 1 : -1;
 45       	if((sign>0 and BP.modeMatches(ix,3,mode)) ||
 46	   (sign<0 and BP.modeMatches(ix,3,mode))) {
 47	  // boost to B rest frame
 48	  LorentzTransform boost =
 49	    LorentzTransform::mkFrameTransformFromBeta(BP.decaying()[ix]. momentum().betaVec());
 50	  // momenta
 51	  FourMomentum pip  = boost.transform(BP.decayProducts()[ix].at( 211*sign)[0].momentum());
 52	  FourMomentum pim  = boost.transform(BP.decayProducts()[ix].at(-211*sign)[0].momentum());
 53	  FourMomentum Kp   = boost.transform(BP.decayProducts()[ix].at( 321*sign)[0].momentum());
 54	  // mass distributions
 55	  double mKpi = (Kp+pim).mass();
 56	  _h_mass[0]->fill(mKpi);
 57	  double mpipi = (pip+pim).mass();
 58	  _h_mass[1]->fill(mpipi);
 59	  // regions for the helicity analysis
 60	  unsigned int imode=0;
 61	  if(mKpi>0.816 && mKpi<0.976 && mpipi>1.5)   imode=0;
 62	  else if(mpipi>0.9 && mpipi<1.1)             imode=1;
 63	  else if(mKpi>0.976&& mKpi<1.8 && mpipi>1.5) imode=2;
 64	  else continue;
 65	  // pi+pi- resonance
 66	  if(imode==1) {
 67	    _h_mass2[imode]->fill(mpipi);
 68	    FourMomentum ppipi = pim+pip;
 69	    LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(ppipi.betaVec());
 70	    double cTheta = boost2.transform(pim).p3().unit().dot(Kp.p3().unit());
 71	    _h_angle[imode]->fill(cTheta);
 72	  }
 73	  // K pi- resonance
 74	  else {
 75	    _h_mass2[imode]->fill(mKpi);
 76	    FourMomentum pKpim = Kp+pim;
 77	    LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pKpim.betaVec());
 78	    double cTheta = boost2.transform(Kp).p3().unit().dot(pip.p3().unit());
 79	    _h_angle[imode]->fill(cTheta);
 80	  }
 81	}
 82      }
 83    }
 84
 85
 86    /// Normalise histograms etc., after the run
 87    void finalize() {
 88      for(unsigned int ix=0; ix<3; ++ix) {
 89	normalize(_h_mass2[ix],1.,false);
 90	normalize(_h_angle[ix],1.,false);
 91	if(ix==2) continue;
 92	normalize(_h_mass[ix],1.,false);
 93      }
 94    }
 95
 96    /// @}
 97
 98
 99    /// @name Histograms
100    /// @{
101    Histo1DPtr _h_mass[2],_h_mass2[3],_h_angle[3];
102    /// @}
103
104
105  };
106
107
108  RIVET_DECLARE_PLUGIN(BABAR_2004_I626730);
109
110}