1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/Beam.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief Spectrum for D_s1
 10  class CLEOII_1993_I352823 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1993_I352823);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      // projections
 23      declare(Beam(), "Beams");
 24      declare(UnstableParticles(), "UFS");
 25      // book histos
 26      book(_h_x     ,3,1,1);
 27      book(_h_cTheta,4,1,1);
 28      book(_r[0],2,1,1);
 29      book(_r[1],2,1,2);
 30    }
 31
 32    bool isK0(int id) {
 33      return id==310 || id==130 || abs(id)==311;
 34    }
 35
 36    /// Perform the per-event analysis
 37    void analyze(const Event& event) {
 38      static const int DsID = 10433;
 39      // Get beams and average beam momentum
 40      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
 41      const double Emax = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
 42      const double Pmax = sqrt(sqr(Emax)-sqr(2.535));
 43      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
 44      for (const Particle& p : ufs.particles(Cuts::abspid==DsID)) {
 45	// spectrum
 46	double xp = p.momentum().p3().mod()/Pmax;
 47        _h_x->fill(xp);
 48	// decay angle
 49	int sign = p.pid()/DsID;
 50	Particle Dstar;
 51	if(p.children().size()!=2) continue;
 52	if(p.children()[0].pid()==sign*423 &&
 53	   p.children()[1].pid()==sign*321) {
 54	  Dstar = p.children()[0];
 55	}
 56	else if(p.children()[1].pid()==sign*423 &&
 57		p.children()[0].pid()==sign*321) {
 58	  Dstar = p.children()[1];
 59	}
 60	else if(p.children()[0].pid()==sign*413 &&
 61		isK0(p.children()[1].pid())) {
 62	  _r[1]->fill(">= 0.0"s);
 63	  continue;
 64      	}
 65      	else if(p.children()[1].pid()==sign*413 &&
 66      		isK0(p.children()[0].pid())) {
 67	  _r[1]->fill(">= 0.0"s);
 68	  continue;
 69      	}
 70	else {
 71	  continue;
 72	}
 73	_r[0]->fill(">= 0.0"s);
 74	if(Dstar.children().size()!=2) continue;
 75	Particle pion;
 76	if(Dstar.children()[0].pid()== 111 &&
 77	   Dstar.children()[1].pid()== sign*421) {
 78	  pion = Dstar.children()[0];
 79	}
 80	else if(Dstar.children()[1].pid()== 111 &&
 81		Dstar.children()[0].pid()== sign*421) {
 82	  pion = Dstar.children()[1];
 83	}
 84	else
 85	  continue;
 86	// first boost to the D_s1 rest frame
 87	LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
 88	FourMomentum pDstar = boost1.transform(Dstar.momentum());
 89	FourMomentum pPion  = boost1.transform(pion .momentum());
 90	// to D* rest frame
 91	LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
 92	Vector3 axis = pDstar.p3().unit();
 93	FourMomentum pp = boost2.transform(pPion);
 94	// calculate angle
 95	double cTheta = pp.p3().unit().dot(axis);
 96	_h_cTheta->fill(cTheta);
 97      }
 98    }
 99
100
101    /// Normalise histograms etc., after the run
102    void finalize() {
103      normalize(_h_x     );
104      normalize(_h_cTheta);
105      scale(_r[0],crossSection()/sumOfWeights()/picobarn);
106      scale(_r[1],crossSection()/sumOfWeights()/picobarn);
107    }
108
109    /// @}
110
111
112    /// @name Histograms
113    /// @{
114    Histo1DPtr _h_x,_h_cTheta;
115    BinnedHistoPtr<string> _r[2];
116    /// @}
117
118
119  };
120
121
122  RIVET_DECLARE_PLUGIN(CLEOII_1993_I352823);
123
124}