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CLEOII_1994_I372349

Spectra for $D_1(2420)^0$ and $D_2^*(2460)^0$
Experiment: CLEOII (CESR)
Inspire ID: 372349
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B331 (1994) 236-244
Beams: e- e+
Beam energies: (5.3, 5.3) GeV
    No run details listed

Measurement of the scaled momentum spectra for $D_1(2420)^0$ and $D^*_2(2460)^0$ mesons at 10.58 GeV.

Source code: CLEOII_1994_I372349.cc
  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  D_10 and D_20 spectra
 10  class CLEOII_1994_I372349 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1994_I372349);
 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_D2_cTheta,2,1,1);
 27      book(_h_D2_x     ,1,1,1);
 28      book(_h_D1_cTheta,2,1,2);
 29      book(_h_D1_x     ,1,1,2);
 30      for(unsigned int ix=0;ix<3;++ix)
 31	book(_r[ix],3,1,ix+1);
 32    }
 33
 34
 35    /// Perform the per-event analysis
 36    void analyze(const Event& event) {
 37      static const int idD1 = 10423;
 38      static const int idD2 = 425;
 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 UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
 43      for (const Particle& p : ufs.particles(Cuts::abspid==idD1 or Cuts::abspid==idD2)) {
 44	if(p.abspid()==idD1) {
 45	  // spectrum
 46	  double Pmax = sqrt(sqr(Emax)-sqr(2.421));
 47	  double xp = p.momentum().p3().mod()/Pmax;
 48	  _h_D1_x->fill(xp);
 49	}
 50	else {
 51	  double Pmax = sqrt(sqr(Emax)-sqr(2.461));
 52	  double xp = p.momentum().p3().mod()/Pmax;
 53	  _h_D2_x->fill(xp);
 54	}
 55	int sign = p.pid()/p.abspid();
 56	Particle Dstar;
 57	if(p.children().size()!=2) continue;
 58	
 59	if(p.children()[0].pid()==sign*413 &&
 60	   p.children()[1].pid()==-sign*211) {
 61	  Dstar = p.children()[0];
 62	}
 63	else if(p.children()[1].pid()==sign*413 &&
 64		p.children()[0].pid()==-sign*211) {
 65	  Dstar = p.children()[1];
 66	}
 67	else if(p.children()[0].pid()==sign*411 &&
 68		p.children()[1].pid()==-sign*211) {
 69	  if(p.abspid()!=idD1) _r[0]->fill(0.5);
 70	  continue;
 71	}
 72	else if(p.children()[1].pid()==sign*411 &&
 73		p.children()[0].pid()==-sign*211) {
 74	  if(p.abspid()!=idD1) _r[0]->fill(0.5);
 75	  continue;
 76	}
 77	else {
 78	  continue;
 79	}
 80	if(p.abspid()==idD1)
 81	  _r[2]->fill(0.5);
 82	else
 83	  _r[1]->fill(0.5);
 84	if(Dstar.children().size()!=2) continue;
 85	Particle pion;
 86	if(Dstar.children()[0].pid()== sign*211 && 
 87	   Dstar.children()[1].pid()== sign*421) {
 88	  pion = Dstar.children()[0];
 89	}
 90	else if(Dstar.children()[1].pid()== sign*211 && 
 91		Dstar.children()[0].pid()== sign*421) {
 92	  pion = Dstar.children()[1];
 93	}
 94	else
 95	  continue;
 96	// first boost to the D_1,2 rest frame
 97	LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
 98	FourMomentum pDstar = boost1.transform(Dstar.momentum());
 99	FourMomentum pPion  = boost1.transform(pion .momentum());
100	// to D* rest frame
101	LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
102	Vector3 axis = pDstar.p3().unit();
103	FourMomentum pp = boost2.transform(pPion);
104	// calculate angle
105	double cTheta = pp.p3().unit().dot(axis);
106	if(p.abspid()==idD1)
107	  _h_D1_cTheta->fill(cTheta);
108	else
109	  _h_D2_cTheta->fill(cTheta);
110      }
111    }
112
113    /// Normalise histograms etc., after the run
114    void finalize() {
115      normalize(_h_D2_cTheta);
116      normalize(_h_D2_x     );
117      normalize(_h_D1_cTheta);
118      normalize(_h_D1_x     );
119      for(unsigned int ix=0;ix<3;++ix)
120	scale(_r[ix],crossSection()/sumOfWeights()/picobarn);
121    }
122
123    ///@}
124
125
126    /// @name Histograms
127    ///@{
128    Histo1DPtr _h_D2_cTheta,_h_D2_x,_h_D1_cTheta,_h_D1_x;
129    Histo1DPtr _r[3];
130    ///@}
131
132
133  };
134
135
136  RIVET_DECLARE_PLUGIN(CLEOII_1994_I372349);
137
138}