[u/mrichter/AliRoot.git] / TEvtGen / EvtGenModels / EvtPartWave.cxx

//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 2000      Caltech, UCSB
//
// Module: EvtHelAmp.cc
//
// Description: Decay model for implementation of generic 2 body
//              decay specified by the partial wave amplitudes
//
//
// Modification history:
//
//    fkw        February 2, 2001     changes to satisfy KCC
//    RYD       September 7, 2000       Module created
//
//------------------------------------------------------------------------
// 
#include "EvtGenBase/EvtPatches.hh"
#include <stdlib.h>
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenBase/EvtTensor4C.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenModels/EvtPartWave.hh"
#include "EvtGenBase/EvtEvalHelAmp.hh"
#include "EvtGenBase/EvtId.hh"
#include <string>
#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtKine.hh"
#include "EvtGenBase/EvtCGCoefSingle.hh"
#include <algorithm>
using std::endl;
EvtPartWave::~EvtPartWave() {}

std::string EvtPartWave::getName(){

  return "PARTWAVE";     

}


EvtDecayBase* EvtPartWave::clone(){

  return new EvtPartWave;

}

void EvtPartWave::init(){

  checkNDaug(2);

  //find out how many states each particle have
  int _nA=EvtSpinType::getSpinStates(EvtPDL::getSpinType(getParentId()));
  int _nB=EvtSpinType::getSpinStates(EvtPDL::getSpinType(getDaug(0)));
  int _nC=EvtSpinType::getSpinStates(EvtPDL::getSpinType(getDaug(1)));

  if (verbose()){
    report(INFO,"EvtGen")<<"_nA,_nB,_nC:"
			 <<_nA<<","<<_nB<<","<<_nC<<endl;
  }

  //find out what 2 times the spin is
  int _JA2=EvtSpinType::getSpin2(EvtPDL::getSpinType(getParentId()));
  int _JB2=EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(0)));
  int _JC2=EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(1)));

  if (verbose()){
    report(INFO,"EvtGen")<<"_JA2,_JB2,_JC2:"
			 <<_JA2<<","<<_JB2<<","<<_JC2<<endl;
  }


  //allocate memory
  int* _lambdaA2=new int[_nA];
  int* _lambdaB2=new int[_nB];
  int* _lambdaC2=new int[_nC];

  EvtComplexPtr* _HBC=new EvtComplexPtr[_nB];
  int ib,ic;
  for(ib=0;ib<_nB;ib++){
    _HBC[ib]=new EvtComplex[_nC];
  }


  int i;
  //find the allowed helicities (actually 2*times the helicity!)

  fillHelicity(_lambdaA2,_nA,_JA2);
  fillHelicity(_lambdaB2,_nB,_JB2);
  fillHelicity(_lambdaC2,_nC,_JC2);

  if (verbose()){
    report(INFO,"EvtGen")<<"Helicity states of particle A:"<<endl;
    for(i=0;i<_nA;i++){
      report(INFO,"EvtGen")<<_lambdaA2[i]<<endl;
    }

    report(INFO,"EvtGen")<<"Helicity states of particle B:"<<endl;
    for(i=0;i<_nB;i++){
      report(INFO,"EvtGen")<<_lambdaB2[i]<<endl;
    }

    report(INFO,"EvtGen")<<"Helicity states of particle C:"<<endl;
    for(i=0;i<_nC;i++){
      report(INFO,"EvtGen")<<_lambdaC2[i]<<endl;
    }

    report(INFO,"EvtGen")<<"Will now figure out the valid (M_LS) states:"<<endl;

  }

  int Lmin=std::max(_JA2-_JB2-_JC2,std::max(_JB2-_JA2-_JC2,_JC2-_JA2-_JB2));
  if (Lmin<0) Lmin=0;
  //int Lmin=_JA2-_JB2-_JC2;
  int Lmax=_JA2+_JB2+_JC2;

  int L;

  int _nPartialWaveAmp=0;

  int _nL[50];
  int _nS[50];

  for (L=Lmin;L<=Lmax;L+=2){
    int Smin=abs(L-_JA2);
    if (Smin<abs(_JB2-_JC2)) Smin=abs(_JB2-_JC2);
    int Smax=L+_JA2;
    if (Smax>abs(_JB2+_JC2)) Smax=abs(_JB2+_JC2);
    int S;
    for (S=Smin;S<=Smax;S+=2){
      _nL[_nPartialWaveAmp]=L;
      _nS[_nPartialWaveAmp]=S;

      _nPartialWaveAmp++;
      if (verbose()){
	report(INFO,"EvtGen")<<"M["<<L<<"]["<<S<<"]"<<endl;    
      }
    }
  }

  checkNArg(_nPartialWaveAmp*2);

  int argcounter=0;

  EvtComplex _M[50];

  double partampsqtot=0.0;

  for(i=0;i<_nPartialWaveAmp;i++){
    _M[i]=getArg(argcounter)*exp(EvtComplex(0.0,getArg(argcounter+1)));;
    argcounter+=2;
    partampsqtot+=abs2(_M[i]);
    if (verbose()){
      report(INFO,"EvtGen")<<"M["<<_nL[i]<<"]["<<_nS[i]<<"]="<<_M[i]<<endl;
    }
  }

  //Now calculate the helicity amplitudes

  double helampsqtot=0.0;
  
  for(ib=0;ib<_nB;ib++){
    for(ic=0;ic<_nC;ic++){
      _HBC[ib][ic]=0.0;
      if (abs(_lambdaB2[ib]-_lambdaC2[ic])<=_JA2){
	for(i=0;i<_nPartialWaveAmp;i++){
	  int L=_nL[i];
	  int S=_nS[i];
	  int lambda2=_lambdaB2[ib];
	  int lambda3=_lambdaC2[ic];
	  int s1=_JA2;
	  int s2=_JB2;
	  int s3=_JC2;
	  int m1=lambda2-lambda3;
	  EvtCGCoefSingle c1(s2,s3);
	  EvtCGCoefSingle c2(L,S);

	  if (verbose()){
	    report(INFO,"EvtGen") << "s2,lambda2:"<<s2<<" "<<lambda2<<endl;
	  }
	  //fkw changes to satisfy KCC
	  double fkwTmp = (L+1.0)/(s1+1.0);

	  if (S>=abs(m1)){

	    EvtComplex tmp=sqrt(fkwTmp)
	      *c1.coef(S,m1,s2,s3,lambda2,-lambda3)
	      *c2.coef(s1,m1,L,S,0,m1)*_M[i];
	    _HBC[ib][ic]+=tmp;
	  }
	}
	if (verbose()){
	  report(INFO,"EvtGen")<<"_HBC["<<ib<<"]["<<ic<<"]="<<_HBC[ib][ic]<<endl;
	}
      }
      helampsqtot+=abs2(_HBC[ib][ic]);
    }
  }

  if (fabs(helampsqtot-partampsqtot)/(helampsqtot+partampsqtot)>1e-6){
      report(ERROR,"EvtGen")<<"In EvtPartWave for decay "
			    << EvtPDL::name(getParentId()) << " -> "
                            << EvtPDL::name(getDaug(0)) << " "     
                            << EvtPDL::name(getDaug(1)) << std::endl; 
      report(ERROR,"EvtGen")<<"With arguments: "<<std::endl;
      for(i=0;i*2<getNArg();i++){
	  report(ERROR,"EvtGen") <<"M("<<_nL[i]<<","<<_nS[i]<<")="
//				 <<getArg(2*i)<<" "<<getArg(2*i+1)<<std::endl;
				 <<_M[i]<<std::endl;
      }
      report(ERROR,"EvtGen")<< "The total probability in the partwave basis is: "
			    << partampsqtot << std::endl;
      report(ERROR,"EvtGen")<< "The total probability in the helamp basis is: "
			    << helampsqtot << std::endl;
      report(ERROR,"EvtGen")<< "Most likely this is because the specified partwave amplitudes "
			    << std::endl;
      report(ERROR,"EvtGen")<< "project onto unphysical helicities of photons or neutrinos. "
			    << std::endl;
      report(ERROR,"EvtGen")<< "Seriously consider if your specified amplitudes are correct. "
			    << std::endl;
      
  
  }
  
  _evalHelAmp=new EvtEvalHelAmp(getParentId(),
				getDaug(0),
				getDaug(1),
				_HBC);

}


void EvtPartWave::initProbMax(){

  double maxprob=_evalHelAmp->probMax();

  if (verbose()){
    report(INFO,"EvtGen")<<"Calculated probmax"<<maxprob<<endl;
  }

  setProbMax(maxprob);

}


void EvtPartWave::decay( EvtParticle *p){

  //first generate simple phase space
  p->initializePhaseSpace(getNDaug(),getDaugs());

  _evalHelAmp->evalAmp(p,_amp2);

  return;

}


void EvtPartWave::fillHelicity(int* lambda2,int n,int J2){
  
  int i;
  
  //photon is special case!
  if (n==2&&J2==2) {
    lambda2[0]=2;
    lambda2[1]=-2;
    return;
  }
  
  assert(n==J2+1);

  for(i=0;i<n;i++){
    lambda2[i]=n-i*2-1;
  }

  return;

}
Commit	Line	Data
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(2i)<<" "<<getArg(2i+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
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