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da0e9ce3 | 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: EvtDiracParticle.cc | |
12 | // | |
13 | // Description: Class to describe spin 1/2 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/EvtDiracParticle.hh" | |
27 | #include "EvtGenBase/EvtVector4R.hh" | |
28 | #include "EvtGenBase/EvtPDL.hh" | |
29 | #include "EvtGenBase/EvtReport.hh" | |
30 | #include "EvtGenBase/EvtSpinDensity.hh" | |
31 | #include "EvtGenBase/EvtGammaMatrix.hh" | |
32 | using std::endl; | |
33 | ||
34 | EvtDiracParticle::~EvtDiracParticle(){} | |
35 | ||
36 | ||
37 | EvtDiracParticle::EvtDiracParticle(){ | |
38 | ||
39 | return; | |
40 | ||
41 | } | |
42 | ||
43 | void EvtDiracParticle::init(EvtId part_n,const EvtVector4R& p4){ | |
44 | ||
45 | _validP4=true; | |
46 | setp(p4); | |
47 | setpart_num(part_n); | |
48 | ||
49 | if (EvtPDL::getStdHep(part_n)==0){ | |
50 | report(ERROR,"EvtGen") << "Error in EvtDiracParticle::init, part_n=" | |
51 | << part_n.getId()<<endl; | |
52 | ::abort(); | |
53 | } | |
54 | ||
55 | if (EvtPDL::getStdHep(part_n)>0){ | |
56 | ||
57 | _spinorRest[0].set(EvtComplex(sqrt(2.0*mass()),0.0),EvtComplex(0.0,0.0), | |
58 | EvtComplex(0.0,0.0),EvtComplex(0.0,0.0)); | |
59 | _spinorRest[1].set(EvtComplex(0.0,0.0),EvtComplex(sqrt(2.0*mass()),0.0), | |
60 | EvtComplex(0.0,0.0),EvtComplex(0.0,0.0)); | |
61 | ||
62 | _spinorParent[0]=boostTo(_spinorRest[0],p4); | |
63 | _spinorParent[1]=boostTo(_spinorRest[1],p4); | |
64 | ||
65 | ||
66 | } | |
67 | else{ | |
68 | ||
69 | _spinorRest[0].set(EvtComplex(0.0,0.0),EvtComplex(0.0,0.0), | |
70 | EvtComplex(sqrt(2.0*mass()),0.0),EvtComplex(0.0,0.0)); | |
71 | _spinorRest[1].set(EvtComplex(0.0,0.0),EvtComplex(0.0,0.0), | |
72 | EvtComplex(0.0,0.0),EvtComplex(sqrt(2.0*mass()),0.0)); | |
73 | ||
74 | _spinorParent[0]=boostTo(_spinorRest[0],p4); | |
75 | _spinorParent[1]=boostTo(_spinorRest[1],p4); | |
76 | ||
77 | ||
78 | ||
79 | } | |
80 | ||
81 | setLifetime(); | |
82 | } | |
83 | ||
84 | ||
85 | void EvtDiracParticle::init(EvtId part_n,const EvtVector4R& p4, | |
86 | const EvtDiracSpinor & prod1, | |
87 | const EvtDiracSpinor & prod2, | |
88 | const EvtDiracSpinor & rest1, | |
89 | const EvtDiracSpinor & rest2){ | |
90 | ||
91 | _validP4=true; | |
92 | setp(p4); | |
93 | setpart_num(part_n); | |
94 | ||
95 | if (EvtPDL::getStdHep(part_n)==0){ | |
96 | report(ERROR,"EvtGen") << "Error in EvtDiracParticle::init, part_n=" | |
97 | << part_n.getId()<<std::endl; | |
98 | ::abort(); | |
99 | } | |
100 | _spinorRest[0]=rest1; | |
101 | _spinorRest[1]=rest2; | |
102 | _spinorParent[0]=prod1; | |
103 | _spinorParent[1]=prod2; | |
104 | ||
105 | setLifetime(); | |
106 | } | |
107 | ||
108 | ||
109 | ||
110 | EvtSpinDensity EvtDiracParticle::rotateToHelicityBasis() const{ | |
111 | ||
112 | EvtDiracSpinor spplus; | |
113 | EvtDiracSpinor spminus; | |
114 | ||
115 | double sqmt2=sqrt(2.*(getP4().mass())); | |
116 | ||
117 | if (EvtPDL::getStdHep(getId())>0){ | |
118 | spplus.set(1.0,0.0,0.0,0.0); | |
119 | spminus.set(0.0,1.0,0.0,0.0); | |
120 | } else { | |
121 | spplus.set(0.0,0.0,0.0,1.0); | |
122 | spminus.set(0.0,0.0,1.0,0.0); | |
123 | } | |
124 | ||
125 | ||
126 | EvtSpinDensity R; | |
127 | R.setDim(2); | |
128 | ||
129 | for (int i=0; i<2; i++) { | |
130 | if (EvtPDL::getStdHep(getId())>0){ | |
131 | R.set(0,i,(EvtComplex)(spplus*_spinorRest[i])/sqmt2); | |
132 | R.set(1,i,(EvtComplex)(spminus*_spinorRest[i])/sqmt2); | |
133 | } else { | |
134 | R.set(0,i,(EvtComplex)(_spinorRest[i]*spplus)/sqmt2); | |
135 | R.set(1,i,(EvtComplex)(_spinorRest[i]*spminus)/sqmt2); | |
136 | } | |
137 | } | |
138 | ||
139 | return R; | |
140 | ||
141 | } | |
142 | ||
143 | ||
144 | EvtSpinDensity EvtDiracParticle::rotateToHelicityBasis(double alpha, | |
145 | double beta, | |
146 | double gamma) const{ | |
147 | ||
148 | ||
149 | EvtDiracSpinor spplus; | |
150 | EvtDiracSpinor spminus; | |
151 | ||
152 | double sqmt2=sqrt(2.*(getP4().mass())); | |
153 | ||
154 | if (EvtPDL::getStdHep(getId())>0){ | |
155 | spplus.set(1.0,0.0,0.0,0.0); | |
156 | spminus.set(0.0,1.0,0.0,0.0); | |
157 | } else { | |
158 | spplus.set(0.0,0.0,0.0,1.0); | |
159 | spminus.set(0.0,0.0,1.0,0.0); | |
160 | } | |
161 | ||
162 | spplus.applyRotateEuler(alpha,beta,gamma); | |
163 | spminus.applyRotateEuler(alpha,beta,gamma); | |
164 | ||
165 | EvtSpinDensity R; | |
166 | R.setDim(2); | |
167 | ||
168 | for (int i=0; i<2; i++) { | |
169 | if (EvtPDL::getStdHep(getId())>0){ | |
170 | R.set(0,i,(EvtComplex)(spplus*_spinorRest[i])/sqmt2); | |
171 | R.set(1,i,(EvtComplex)(spminus*_spinorRest[i])/sqmt2); | |
172 | } else { | |
173 | R.set(0,i,(EvtComplex)(_spinorRest[i]*spplus)/sqmt2); | |
174 | R.set(1,i,(EvtComplex)(_spinorRest[i]*spminus)/sqmt2); | |
175 | } | |
176 | } | |
177 | ||
178 | return R; | |
179 | ||
180 | } | |
181 | ||
182 | ||
183 |