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 B0 -> psi(2S) K+ pi-
 10  class BELLE_2013_I1239347 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2013_I1239347);
 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==511);
 24      declare(ufs, "UFS");
 25      DecayedParticles B0(ufs);
 26      B0.addStable(100443);
 27      declare(B0, "B0");
 28      // histograms
 29      for(unsigned int ix=0;ix<8;++ix)
 30	book(_h_mass[ix],1,1,1+ix);
 31      book(_h_mass[8],2,1,1);
 32      for(unsigned int ix=0;ix<2;++ix)
 33	book(_h_angle[ix],3,1,1+ix);
 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}, { 100443,1}};
 40      static const map<PdgId,unsigned int> & modeCC = { {-321,1},{ 211,1}, { 100443,1}};
 41      DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
 42      // loop over particles
 43      for(unsigned int ix=0;ix<B0.decaying().size();++ix) {
 44      	int sign = 1;
 45      	if (B0.decaying()[ix].pid()>0 && B0.modeMatches(ix,3,mode)) {
 46      	  sign=1;
 47      	}
 48      	else if  (B0.decaying()[ix].pid()<0 && B0.modeMatches(ix,3,modeCC)) {
 49      	  sign=-1;
 50      	}
 51      	else
 52      	  continue;
 53      	const Particle & Kp  = B0.decayProducts()[ix].at( 321*sign)[0];
 54      	const Particle & pim = B0.decayProducts()[ix].at(-211*sign)[0];
 55	const Particle & psi = B0.decayProducts()[ix].at( 100443  )[0];
 56	double mKpi   = (Kp .momentum()+pim.momentum()).mass();
 57	double m2Psipi= (psi.momentum()+pim.momentum()).mass2();
 58	if(m2Psipi<19.)                       _h_mass[0]->fill(sqr(mKpi));
 59	else if(m2Psipi>=19. && m2Psipi<20.5) _h_mass[1]->fill(sqr(mKpi));
 60	else if(m2Psipi>=20.5)                _h_mass[2]->fill(sqr(mKpi));
 61
 62	if(mKpi<0.796) {
 63	  _h_mass[3]->fill(m2Psipi);
 64	  _h_mass[8]->fill(m2Psipi);
 65	}
 66	else if(mKpi>=0.796&&mKpi<0.996)
 67	  _h_mass[4]->fill(m2Psipi);
 68	else if(mKpi>=0.996&&mKpi<1.332) {
 69	  _h_mass[5]->fill(m2Psipi);
 70	  _h_mass[8]->fill(m2Psipi);
 71	}
 72	else if(mKpi>=1.332&&mKpi<1.532)
 73	  _h_mass[6]->fill(m2Psipi);
 74	else if(mKpi>=1.532) {
 75	  _h_mass[7]->fill(m2Psipi);
 76	  _h_mass[8]->fill(m2Psipi);
 77	}
 78	// need leptonic psi' decay for angular dists
 79	if(psi.children().size()!=2|| psi.children()[0].pid()!=-psi.children()[1].pid() ||
 80	   (psi.children()[0].abspid()!=11 &&
 81	    psi.children()[0].abspid()!=11)) vetoEvent;
 82	Particle lm = psi.children()[0];
 83	Particle lp = psi.children()[1];
 84	if(lm.pid()<0) swap(lm,lp);
 85	LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(B0.decaying()[ix].momentum().betaVec());
 86	FourMomentum pKstar = boost1.transform(Kp.momentum()+pim.momentum());
 87	FourMomentum pPsi   = boost1.transform(psi.momentum());
 88	// trans vector in K* frame
 89	LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
 90	FourMomentum pKp = boost2.transform(boost1.transform(Kp.momentum()));
 91	Vector3 axis1 = pKstar.p3().unit();
 92	double cTheta1 = axis1.dot(pKp.p3().unit());
 93	Vector3 trans1 = pKp.p3() - cTheta1*pKp.p3().mod()*axis1;
 94	// leptons in psi' frame
 95	LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pPsi.betaVec());
 96	FourMomentum plm = boost3.transform(boost1.transform(lm.momentum()));
 97	double cTheta2 = axis1.dot(plm.p3().unit());
 98	Vector3 trans2 = plm.p3() - cTheta2*plm.p3().mod()*axis1;
 99	_h_angle[0]->fill(cTheta2);
100	// angle between planes
101	double chi = atan2(trans1.cross(trans2).dot(axis1),trans1.dot(trans2));
102	_h_angle[1]->fill(chi);
103      }
104    }
105
106
107    /// Normalise histograms etc., after the run
108    void finalize() {
109      for(unsigned int ix=0;ix<9;++ix)
110	normalize(_h_mass[ix],1.,false);
111      normalize(_h_angle[0],1.,false);
112      normalize(_h_angle[1],1.,false);
113    }
114
115    /// @}
116
117
118    /// @name Histograms
119    /// @{
120    Histo1DPtr _h_mass[9],_h_angle[2];
121    /// @}
122
123
124  };
125
126
127  RIVET_DECLARE_PLUGIN(BELLE_2013_I1239347);
128
129}