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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) 2000 Caltech, UCSB | |
10 | // | |
11 | // Module: EvtHelAmp.cc | |
12 | // | |
13 | // Description: Decay model for implementation of generic 2 body | |
14 | // decay specified by the partial wave amplitudes | |
15 | // | |
16 | // | |
17 | // Modification history: | |
18 | // | |
19 | // fkw February 2, 2001 changes to satisfy KCC | |
20 | // RYD September 7, 2000 Module created | |
21 | // | |
22 | //------------------------------------------------------------------------ | |
23 | // | |
24 | #include "EvtGenBase/EvtPatches.hh" | |
25 | #include <stdlib.h> | |
26 | #include "EvtGenBase/EvtParticle.hh" | |
27 | #include "EvtGenBase/EvtGenKine.hh" | |
28 | #include "EvtGenBase/EvtPDL.hh" | |
29 | #include "EvtGenBase/EvtVector4C.hh" | |
30 | #include "EvtGenBase/EvtTensor4C.hh" | |
31 | #include "EvtGenBase/EvtReport.hh" | |
32 | #include "EvtGenModels/EvtPartWave.hh" | |
33 | #include "EvtGenBase/EvtEvalHelAmp.hh" | |
34 | #include "EvtGenBase/EvtId.hh" | |
35 | #include <string> | |
36 | #include "EvtGenBase/EvtConst.hh" | |
37 | #include "EvtGenBase/EvtKine.hh" | |
38 | #include "EvtGenBase/EvtCGCoefSingle.hh" | |
39 | #include <algorithm> | |
40 | using std::endl; | |
41 | EvtPartWave::~EvtPartWave() {} | |
42 | ||
43 | std::string EvtPartWave::getName(){ | |
44 | ||
45 | return "PARTWAVE"; | |
46 | ||
47 | } | |
48 | ||
49 | ||
50 | EvtDecayBase* EvtPartWave::clone(){ | |
51 | ||
52 | return new EvtPartWave; | |
53 | ||
54 | } | |
55 | ||
56 | void EvtPartWave::init(){ | |
57 | ||
58 | checkNDaug(2); | |
59 | ||
60 | //find out how many states each particle have | |
61 | int _nA=EvtSpinType::getSpinStates(EvtPDL::getSpinType(getParentId())); | |
62 | int _nB=EvtSpinType::getSpinStates(EvtPDL::getSpinType(getDaug(0))); | |
63 | int _nC=EvtSpinType::getSpinStates(EvtPDL::getSpinType(getDaug(1))); | |
64 | ||
65 | if (verbose()){ | |
66 | report(INFO,"EvtGen")<<"_nA,_nB,_nC:" | |
67 | <<_nA<<","<<_nB<<","<<_nC<<endl; | |
68 | } | |
69 | ||
70 | //find out what 2 times the spin is | |
71 | int _JA2=EvtSpinType::getSpin2(EvtPDL::getSpinType(getParentId())); | |
72 | int _JB2=EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(0))); | |
73 | int _JC2=EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(1))); | |
74 | ||
75 | if (verbose()){ | |
76 | report(INFO,"EvtGen")<<"_JA2,_JB2,_JC2:" | |
77 | <<_JA2<<","<<_JB2<<","<<_JC2<<endl; | |
78 | } | |
79 | ||
80 | ||
81 | //allocate memory | |
82 | int* _lambdaA2=new int[_nA]; | |
83 | int* _lambdaB2=new int[_nB]; | |
84 | int* _lambdaC2=new int[_nC]; | |
85 | ||
86 | EvtComplexPtr* _HBC=new EvtComplexPtr[_nB]; | |
87 | int ib,ic; | |
88 | for(ib=0;ib<_nB;ib++){ | |
89 | _HBC[ib]=new EvtComplex[_nC]; | |
90 | } | |
91 | ||
92 | ||
93 | int i; | |
94 | //find the allowed helicities (actually 2*times the helicity!) | |
95 | ||
96 | fillHelicity(_lambdaA2,_nA,_JA2); | |
97 | fillHelicity(_lambdaB2,_nB,_JB2); | |
98 | fillHelicity(_lambdaC2,_nC,_JC2); | |
99 | ||
100 | if (verbose()){ | |
101 | report(INFO,"EvtGen")<<"Helicity states of particle A:"<<endl; | |
102 | for(i=0;i<_nA;i++){ | |
103 | report(INFO,"EvtGen")<<_lambdaA2[i]<<endl; | |
104 | } | |
105 | ||
106 | report(INFO,"EvtGen")<<"Helicity states of particle B:"<<endl; | |
107 | for(i=0;i<_nB;i++){ | |
108 | report(INFO,"EvtGen")<<_lambdaB2[i]<<endl; | |
109 | } | |
110 | ||
111 | report(INFO,"EvtGen")<<"Helicity states of particle C:"<<endl; | |
112 | for(i=0;i<_nC;i++){ | |
113 | report(INFO,"EvtGen")<<_lambdaC2[i]<<endl; | |
114 | } | |
115 | ||
116 | report(INFO,"EvtGen")<<"Will now figure out the valid (M_LS) states:"<<endl; | |
117 | ||
118 | } | |
119 | ||
120 | int Lmin=std::max(_JA2-_JB2-_JC2,std::max(_JB2-_JA2-_JC2,_JC2-_JA2-_JB2)); | |
121 | if (Lmin<0) Lmin=0; | |
122 | //int Lmin=_JA2-_JB2-_JC2; | |
123 | int Lmax=_JA2+_JB2+_JC2; | |
124 | ||
125 | int L; | |
126 | ||
127 | int _nPartialWaveAmp=0; | |
128 | ||
129 | int _nL[50]; | |
130 | int _nS[50]; | |
131 | ||
132 | for (L=Lmin;L<=Lmax;L+=2){ | |
133 | int Smin=abs(L-_JA2); | |
134 | if (Smin<abs(_JB2-_JC2)) Smin=abs(_JB2-_JC2); | |
135 | int Smax=L+_JA2; | |
136 | if (Smax>abs(_JB2+_JC2)) Smax=abs(_JB2+_JC2); | |
137 | int S; | |
138 | for (S=Smin;S<=Smax;S+=2){ | |
139 | _nL[_nPartialWaveAmp]=L; | |
140 | _nS[_nPartialWaveAmp]=S; | |
141 | ||
142 | _nPartialWaveAmp++; | |
143 | if (verbose()){ | |
144 | report(INFO,"EvtGen")<<"M["<<L<<"]["<<S<<"]"<<endl; | |
145 | } | |
146 | } | |
147 | } | |
148 | ||
149 | checkNArg(_nPartialWaveAmp*2); | |
150 | ||
151 | int argcounter=0; | |
152 | ||
153 | EvtComplex _M[50]; | |
154 | ||
155 | double partampsqtot=0.0; | |
156 | ||
157 | for(i=0;i<_nPartialWaveAmp;i++){ | |
158 | _M[i]=getArg(argcounter)*exp(EvtComplex(0.0,getArg(argcounter+1)));; | |
159 | argcounter+=2; | |
160 | partampsqtot+=abs2(_M[i]); | |
161 | if (verbose()){ | |
162 | report(INFO,"EvtGen")<<"M["<<_nL[i]<<"]["<<_nS[i]<<"]="<<_M[i]<<endl; | |
163 | } | |
164 | } | |
165 | ||
166 | //Now calculate the helicity amplitudes | |
167 | ||
168 | double helampsqtot=0.0; | |
169 | ||
170 | for(ib=0;ib<_nB;ib++){ | |
171 | for(ic=0;ic<_nC;ic++){ | |
172 | _HBC[ib][ic]=0.0; | |
173 | if (abs(_lambdaB2[ib]-_lambdaC2[ic])<=_JA2){ | |
174 | for(i=0;i<_nPartialWaveAmp;i++){ | |
175 | int L=_nL[i]; | |
176 | int S=_nS[i]; | |
177 | int lambda2=_lambdaB2[ib]; | |
178 | int lambda3=_lambdaC2[ic]; | |
179 | int s1=_JA2; | |
180 | int s2=_JB2; | |
181 | int s3=_JC2; | |
182 | int m1=lambda2-lambda3; | |
183 | EvtCGCoefSingle c1(s2,s3); | |
184 | EvtCGCoefSingle c2(L,S); | |
185 | ||
186 | if (verbose()){ | |
187 | report(INFO,"EvtGen") << "s2,lambda2:"<<s2<<" "<<lambda2<<endl; | |
188 | } | |
189 | //fkw changes to satisfy KCC | |
190 | double fkwTmp = (L+1.0)/(s1+1.0); | |
191 | ||
192 | if (S>=abs(m1)){ | |
193 | ||
194 | EvtComplex tmp=sqrt(fkwTmp) | |
195 | *c1.coef(S,m1,s2,s3,lambda2,-lambda3) | |
196 | *c2.coef(s1,m1,L,S,0,m1)*_M[i]; | |
197 | _HBC[ib][ic]+=tmp; | |
198 | } | |
199 | } | |
200 | if (verbose()){ | |
201 | report(INFO,"EvtGen")<<"_HBC["<<ib<<"]["<<ic<<"]="<<_HBC[ib][ic]<<endl; | |
202 | } | |
203 | } | |
204 | helampsqtot+=abs2(_HBC[ib][ic]); | |
205 | } | |
206 | } | |
207 | ||
208 | if (fabs(helampsqtot-partampsqtot)/(helampsqtot+partampsqtot)>1e-6){ | |
209 | report(ERROR,"EvtGen")<<"In EvtPartWave for decay " | |
210 | << EvtPDL::name(getParentId()) << " -> " | |
211 | << EvtPDL::name(getDaug(0)) << " " | |
212 | << EvtPDL::name(getDaug(1)) << std::endl; | |
213 | report(ERROR,"EvtGen")<<"With arguments: "<<std::endl; | |
214 | for(i=0;i*2<getNArg();i++){ | |
215 | report(ERROR,"EvtGen") <<"M("<<_nL[i]<<","<<_nS[i]<<")=" | |
216 | // <<getArg(2*i)<<" "<<getArg(2*i+1)<<std::endl; | |
217 | <<_M[i]<<std::endl; | |
218 | } | |
219 | report(ERROR,"EvtGen")<< "The total probability in the partwave basis is: " | |
220 | << partampsqtot << std::endl; | |
221 | report(ERROR,"EvtGen")<< "The total probability in the helamp basis is: " | |
222 | << helampsqtot << std::endl; | |
223 | report(ERROR,"EvtGen")<< "Most likely this is because the specified partwave amplitudes " | |
224 | << std::endl; | |
225 | report(ERROR,"EvtGen")<< "project onto unphysical helicities of photons or neutrinos. " | |
226 | << std::endl; | |
227 | report(ERROR,"EvtGen")<< "Seriously consider if your specified amplitudes are correct. " | |
228 | << std::endl; | |
229 | ||
230 | ||
231 | } | |
232 | ||
233 | _evalHelAmp=new EvtEvalHelAmp(getParentId(), | |
234 | getDaug(0), | |
235 | getDaug(1), | |
236 | _HBC); | |
237 | ||
238 | } | |
239 | ||
240 | ||
241 | void EvtPartWave::initProbMax(){ | |
242 | ||
243 | double maxprob=_evalHelAmp->probMax(); | |
244 | ||
245 | if (verbose()){ | |
246 | report(INFO,"EvtGen")<<"Calculated probmax"<<maxprob<<endl; | |
247 | } | |
248 | ||
249 | setProbMax(maxprob); | |
250 | ||
251 | } | |
252 | ||
253 | ||
254 | void EvtPartWave::decay( EvtParticle *p){ | |
255 | ||
256 | //first generate simple phase space | |
257 | p->initializePhaseSpace(getNDaug(),getDaugs()); | |
258 | ||
259 | _evalHelAmp->evalAmp(p,_amp2); | |
260 | ||
261 | return; | |
262 | ||
263 | } | |
264 | ||
265 | ||
266 | ||
267 | void EvtPartWave::fillHelicity(int* lambda2,int n,int J2){ | |
268 | ||
269 | int i; | |
270 | ||
271 | //photon is special case! | |
272 | if (n==2&&J2==2) { | |
273 | lambda2[0]=2; | |
274 | lambda2[1]=-2; | |
275 | return; | |
276 | } | |
277 | ||
278 | assert(n==J2+1); | |
279 | ||
280 | for(i=0;i<n;i++){ | |
281 | lambda2[i]=n-i*2-1; | |
282 | } | |
283 | ||
284 | return; | |
285 | ||
286 | } | |
287 | ||
288 | ||
289 | ||
290 | ||
291 | ||
292 | ||
293 | ||
294 | ||
295 | ||
296 | ||
297 |