1 //--------------------------------------------------------------------------
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.
8 // Copyright Information: See EvtGen/COPYRIGHT
9 // Copyright (C) 1998 Caltech, UCSB
11 // Module: EvtVectorParticle.cc
13 // Description: Class to describe spin 1 particles
15 // Modification history:
17 // DJL/RYD September 25, 1996 Module created
19 //------------------------------------------------------------------------
21 #include "EvtGenBase/EvtPatches.hh"
25 #include "EvtGenBase/EvtComplex.hh"
26 #include "EvtGenBase/EvtVectorParticle.hh"
27 #include "EvtGenBase/EvtVector4C.hh"
28 #include "EvtGenBase/EvtPDL.hh"
29 #include "EvtGenBase/EvtReport.hh"
31 EvtVectorParticle::~EvtVectorParticle(){}
34 void EvtVectorParticle::init(EvtId part_n,double e,double px,double py,double pz){
40 _eps[0].set(0.0,1.0,0.0,0.0);
41 _eps[1].set(0.0,0.0,1.0,0.0);
42 _eps[2].set(0.0,0.0,0.0,1.0);
47 void EvtVectorParticle::init(EvtId part_n,const EvtVector4R& p4){
53 _eps[0].set(0.0,1.0,0.0,0.0);
54 _eps[1].set(0.0,0.0,1.0,0.0);
55 _eps[2].set(0.0,0.0,0.0,1.0);
59 void EvtVectorParticle::init(EvtId part_n,const EvtVector4R& p4,
60 const EvtVector4C & epsin1,
61 const EvtVector4C & epsin2,
62 const EvtVector4C & epsin3){
77 EvtSpinDensity EvtVectorParticle::rotateToHelicityBasis() const{
79 static EvtVector4C eplus(0.0,-1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
80 static EvtVector4C ezero(0.0,0.0,0.0,1.0);
81 static EvtVector4C eminus(0.0,1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
83 static EvtVector4C eplusC(eplus.conj());
84 static EvtVector4C ezeroC(ezero.conj());
85 static EvtVector4C eminusC(eminus.conj());
90 for ( int i=0; i<3; i++ ) {
91 R.set(0,i,(eplusC)*_eps[i]);
92 R.set(1,i,(ezeroC)*_eps[i]);
93 R.set(2,i,(eminusC)*_eps[i]);
101 EvtSpinDensity EvtVectorParticle::rotateToHelicityBasis(double alpha,
105 EvtVector4C eplus(0.0,-1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
106 EvtVector4C ezero(0.0,0.0,0.0,1.0);
107 EvtVector4C eminus(0.0,1.0/sqrt(2.0),EvtComplex(0.0,-1.0/sqrt(2.0)),0.0);
109 eplus.applyRotateEuler(alpha,beta,gamma);
110 ezero.applyRotateEuler(alpha,beta,gamma);
111 eminus.applyRotateEuler(alpha,beta,gamma);
117 for ( int i=0; i<3; i++ ) {
118 R.set(0,i,(eplus.conj())*_eps[i]);
119 R.set(1,i,(ezero.conj())*_eps[i]);
120 R.set(2,i,(eminus.conj())*_eps[i]);