TEvtGen/EvtGenBase/EvtTensorParticle.cpp

   1 //--------------------------------------------------------------------------
   2 //
   3 // Environment:
   4 //      This software is part of the EvtGen package developed jointly
   5 //      for the BaBar and CLEO collaborations.  If you use all or part
   6 //      of it, please give an appropriate acknowledgement.
   7 //
   8 // Copyright Information: See EvtGen/COPYRIGHT
   9 //      Copyright (C) 1998      Caltech, UCSB
  10 //
  11 // Module: EvtTensorParticle.cc
  12 //
  13 // Description: Class to describe spin 2 particles.
  14 //
  15 // Modification history:
  16 //
  17 //    DJL/RYD   September 25,1996           Module created
  18 //
  19 //------------------------------------------------------------------------
  20 //
  21 #include "EvtGenBase/EvtPatches.hh"
  22 #include <stdlib.h>
  23 #include <iostream>
  24 #include <math.h>
  25 #include "EvtGenBase/EvtComplex.hh"
  26 #include "EvtGenBase/EvtVector4R.hh"
  27 #include "EvtGenBase/EvtTensor4C.hh"
  28 #include "EvtGenBase/EvtVector4C.hh"
  29 #include "EvtGenBase/EvtTensorParticle.hh"
  30 #include "EvtGenBase/EvtReport.hh"
  31
  32 EvtTensorParticle::~EvtTensorParticle(){}
  33
  34 void EvtTensorParticle::init(EvtId part_n,const EvtVector4R& p4){
  35
  36   init(part_n,p4.get(0),p4.get(1)
  37        ,p4.get(2),p4.get(3));
  38
  39   setLifetime();
  40
  41
  42 }
  43
  44 void EvtTensorParticle::init(EvtId part_n,double e,double px,double py,double pz){
  45
  46   _validP4=true;
  47   setp(e,px,py,pz);
  48   setpart_num(part_n);
  49
  50   eps[0].setdiag(0.0,-1.0/sqrt(6.0),-1.0/sqrt(6.0),
  51                2.0/sqrt(6.0));
  52   eps[1].setdiag(0.0,1.0/sqrt(2.0),-1.0/sqrt(2.0),0.0);
  53   eps[2].setdiag(0.0,0.0,0.0,0.0);
  54   eps[3].setdiag(0.0,0.0,0.0,0.0);
  55   eps[4].setdiag(0.0,0.0,0.0,0.0);
  56
  57   eps[2].set(1,2,EvtComplex(1.0/sqrt(2.0),0.0));
  58   eps[2].set(2,1,EvtComplex(1.0/sqrt(2.0),0.0));
  59   eps[3].set(1,3,EvtComplex(1.0/sqrt(2.0),0.0));
  60   eps[3].set(3,1,EvtComplex(1.0/sqrt(2.0),0.0));
  61   eps[4].set(2,3,EvtComplex(1.0/sqrt(2.0),0.0));
  62   eps[4].set(3,2,EvtComplex(1.0/sqrt(2.0),0.0));
  63
  64   setLifetime();
  65
  66 }
  67
  68
  69 void EvtTensorParticle::init(EvtId part_n,const EvtVector4R& p4,
  70                              const EvtTensor4C& epsin1,
  71                              const EvtTensor4C& epsin2,
  72                              const EvtTensor4C& epsin3,
  73                              const EvtTensor4C& epsin4,
  74                              const EvtTensor4C& epsin5){
  75
  76   _validP4=true;
  77   setp(p4);
  78   setpart_num(part_n);
  79
  80   eps[0]=epsin1;
  81   eps[1]=epsin2;
  82   eps[2]=epsin3;
  83   eps[3]=epsin4;
  84   eps[4]=epsin5;
  85
  86   setLifetime();
  87
  88 }
  89
  90
  91
  92 EvtTensor4C EvtTensorParticle::epsTensorParent(int i) const {
  93
  94   EvtTensor4C temp=eps[i];
  95
  96   temp.applyBoostTo(this->getP4());
  97   return temp;
  98
  99 } //epsParent
 100
 101
 102 EvtTensor4C EvtTensorParticle::epsTensor(int i) const {
 103
 104   return eps[i];
 105
 106 } //eps
 107
 108
 109
 110 EvtSpinDensity EvtTensorParticle::rotateToHelicityBasis() const{
 111
 112
 113   static EvtVector4C eplus(0.0,-1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
 114   static EvtVector4C ezero(0.0,0.0,0.0,1.0);
 115   static EvtVector4C eminus(0.0,1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
 116
 117   static EvtTensor4C dPpp(EvtGenFunctions::directProd(eplus,eplus));
 118   static EvtTensor4C dPp0(EvtGenFunctions::directProd(eplus,ezero));
 119   static EvtTensor4C dP0p(EvtGenFunctions::directProd(ezero,eplus));
 120   static EvtTensor4C dPpm(EvtGenFunctions::directProd(eplus,eminus));
 121   static EvtTensor4C dP00(EvtGenFunctions::directProd(ezero,ezero));
 122   static EvtTensor4C dPmp(EvtGenFunctions::directProd(eminus,eplus));
 123   static EvtTensor4C dPmm(EvtGenFunctions::directProd(eminus,eminus));
 124   static EvtTensor4C dPm0(EvtGenFunctions::directProd(eminus,ezero));
 125   static EvtTensor4C dP0m(EvtGenFunctions::directProd(ezero,eminus));
 126
 127   static EvtTensor4C es0(conj(dPpp));
 128   static EvtTensor4C es1(conj((1/sqrt(2.0))*dPp0 +(1/sqrt(2.0))*dP0p));
 129   static EvtTensor4C es2(conj((1/sqrt(6.0))*dPpm +(2/sqrt(6.0))*dP00 +(1/sqrt(6.0))*dPmp));
 130   static EvtTensor4C es3(conj((1/sqrt(2.0))*dPm0  +(1/sqrt(2.0))*dP0m));
 131   static EvtTensor4C es4(conj(dPmm));
 132
 133
 134   EvtSpinDensity R;
 135   R.setDim(5);
 136
 137   for (int j=0; j<5; j++) {
 138     R.set(0,j,cont(es0,eps[j]));
 139     R.set(1,j,cont(es1,eps[j]));
 140     R.set(2,j,cont(es2,eps[j]));
 141     R.set(3,j,cont(es3,eps[j]));
 142     R.set(4,j,cont(es4,eps[j]));
 143   }
 144   return R;
 145
 146 }
 147
 148
 149 EvtSpinDensity EvtTensorParticle::rotateToHelicityBasis(double alpha,
 150                                                         double beta,
 151                                                         double gamma) const{
 152
 153   EvtTensor4C es[5];
 154
 155   static EvtVector4C eplus(0.0,-1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
 156   static EvtVector4C ezero(0.0,0.0,0.0,1.0);
 157   static EvtVector4C eminus(0.0,1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
 158
 159   eplus.applyRotateEuler(alpha,beta,gamma);
 160   ezero.applyRotateEuler(alpha,beta,gamma);
 161   eminus.applyRotateEuler(alpha,beta,gamma);
 162
 163   for (int i=0; i<5; i++) es[i].zero();
 164
 165   es[0]=EvtGenFunctions::directProd(eplus,eplus);
 166   es[1] =(1/sqrt(2.0))*EvtGenFunctions::directProd(eplus,ezero)
 167     +(1/sqrt(2.0))*EvtGenFunctions::directProd(ezero,eplus);
 168   es[2] =(1/sqrt(6.0))*EvtGenFunctions::directProd(eplus,eminus)
 169     +(2/sqrt(6.0))*EvtGenFunctions::directProd(ezero,ezero)
 170     +(1/sqrt(6.0))*EvtGenFunctions::directProd(eminus,eplus);
 171   es[3] =(1/sqrt(2.0))*EvtGenFunctions::directProd(eminus,ezero)
 172     +(1/sqrt(2.0))*EvtGenFunctions::directProd(ezero,eminus);
 173   es[4]=EvtGenFunctions::directProd(eminus,eminus);
 174
 175   for (int i=0; i<5; i++) es[i]=conj(es[i]);
 176
 177   EvtSpinDensity R;
 178   R.setDim(5);
 179
 180   for (int i=0; i<5; i++)
 181     for (int j=0; j<5; j++)
 182         R.set(i,j,cont(es[i],eps[j]));
 183
 184   return R;
 185
 186 }
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