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Converting TEvtGen to native cmake
[u/mrichter/AliRoot.git] / TEvtGen / EvtGen / EvtGenModels / EvtBcToNPi.cpp
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0ca57c2f 1//--------------------------------------------------------------------------
2//
3// Environment:
4// This software is part of the EvtGen package. If you use all or part
5// of it, please give an appropriate acknowledgement.
6//
7// Copyright Information: See EvtGen/COPYRIGHT
8//
9// Module: EvtGenModels/EvtBcToNPi.hh
10//
11// Description: General decay model for Bc -> V + npi and Bc -> P + npi
12//
13// Modification history:
14//
15// A.Berezhnoy, A.Likhoded, A.Luchinsky April 2011 Module created
16//
17//------------------------------------------------------------------------
18
19#include "EvtGenBase/EvtPatches.hh"
20
21#include "EvtGenBase/EvtPDL.hh"
22#include "EvtGenBase/EvtReport.hh"
23#include "EvtGenBase/EvtVector4C.hh"
24#include "EvtGenBase/EvtTensor4C.hh"
25#include "EvtGenBase/EvtIdSet.hh"
26#include "EvtGenBase/EvtSpinType.hh"
27#include "EvtGenBase/EvtScalarParticle.hh"
28
29#include "EvtGenModels/EvtBcToNPi.hh"
30
31#include <iostream>
32using std::endl;
33
34EvtBcToNPi::EvtBcToNPi(bool printAuthorInfo) {
35 nCall=0; maxAmp2=0;
36 if (printAuthorInfo == true) {this->printAuthorInfo();}
37}
38
39EvtBcToNPi::~EvtBcToNPi() {
40}
41
42std::string EvtBcToNPi::getName(){
43
44 return "EvtBcToNPi";
45
46}
47
48EvtDecayBase* EvtBcToNPi::clone(){
49
50 return new EvtBcToNPi;
51
52}
53
54
55void EvtBcToNPi::init(){
56
57 // check spins
58 checkSpinParent(EvtSpinType::SCALAR);
59
60
61 // the others are scalar
62 for (int i=1; i<=(getNDaug()-1);i++) {
63 checkSpinDaughter(i,EvtSpinType::SCALAR);
64 };
65
66 _beta=-0.108; _mRho=0.775; _gammaRho=0.149;
67 _mRhopr=1.364; _gammaRhopr=0.400; _mA1=1.23; _gammaA1=0.4;
68
69 // read arguments
70 if( EvtPDL::getSpinType(getDaug(0)) == EvtSpinType::VECTOR) {
71 checkNArg(10);
72 int n=0;
73 _maxProb=getArg(n++);
74 FA0_N=getArg(n++);
75 FA0_c1=getArg(n++);
76 FA0_c2=getArg(n++);
77 FAp_N=getArg(n++);
78 FAp_c1=getArg(n++);
79 FAp_c2=getArg(n++);
80 FV_N=getArg(n++);
81 FV_c1=getArg(n++);
82 FV_c2=getArg(n++);
83 FAm_N=0;
84 FAm_c1=0;
85 FAm_c2=0;
86 }
87 else if( EvtPDL::getSpinType(getDaug(0)) == EvtSpinType::SCALAR) {
88 checkNArg(4);
89 int n=0;
90 _maxProb=getArg(n++);
91 Fp_N=getArg(n++);
92 Fp_c1=getArg(n++);
93 Fp_c2=getArg(n++);
94 Fm_N=0;
95 Fm_c1=0;
96 Fm_c2=0;
97 }
98 else {
99 report(ERROR,"EvtGen") << "Have not yet implemented this final state in BCPSINPI model" << endl;
100 report(ERROR,"EvtGen") << "Ndaug="<<getNDaug() << endl;
101 for ( int id=0; id<(getNDaug()-1); id++ )
102 report(ERROR,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
103 return;
104
105 };
106
107 if(getNDaug()<2 || getNDaug()>4) {
108 report(ERROR,"EvtGen") << "Have not yet implemented this final state in BCPSINPI model" << endl;
109 report(ERROR,"EvtGen") << "Ndaug="<<getNDaug() << endl;
110 for ( int id=0; id<(getNDaug()-1); id++ )
111 report(ERROR,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
112 return;
113 }
114
115}
116
117double EvtBcToNPi::_ee(double M, double m1, double m2) {
118 return (M*M+m1*m1-m2*m2)/(2*M);
119};
120
121double EvtBcToNPi::_pp(double M, double m1, double m2) {
122 double __ee=_ee(M,m1,m2);
123 return sqrt(__ee*__ee-m1*m1);
124};
125
126
127void EvtBcToNPi::initProbMax(){
128 if(_maxProb>0.) setProbMax(_maxProb);
129 else {
130 EvtId id=getParentId();
131 EvtScalarParticle *p=new EvtScalarParticle();
132 p->init(id, EvtPDL::getMass(id),0., 0., 0.);
133 p->setDiagonalSpinDensity();
134 // add daughters
135 p->makeDaughters(getNDaug(), getDaugs() );
136
137 // fill the momenta
138 if(getNDaug()==2) {
139 double M=EvtPDL::getMass(id), m1=EvtPDL::getMass(getDaug(0)), m2=EvtPDL::getMass(getDaug(1));
140 double __pp=_pp(M,m1,m2);
141 p->getDaug(0)->setP4( EvtVector4R( _ee(M,m1,m2), 0., 0., __pp) );
142 p->getDaug(1)->setP4( EvtVector4R( _ee(M,m2,m1), 0., 0., -__pp) );
143 }
144 else if( getNDaug()==3) {
145 double M=EvtPDL::getMass(id),
146 m1=EvtPDL::getMass(getDaug(0)),
147 m2=EvtPDL::getMass(getDaug(1)),
148 m3=EvtPDL::getMass(getDaug(2));
149 double __ppRho=_pp(M,m1,_mRho), __ppPi=_pp(_mRho,m2,m3);
150 p->getDaug(0)->setP4( EvtVector4R( _ee(M,m1,_mRho), 0., 0., __ppRho) );
151 EvtVector4R _pRho( _ee(M,_mRho,m1), 0., 0., -__ppRho);
152 EvtVector4R _p2( _ee(_mRho, m2, m3), 0., 0., __ppPi); _p2.applyBoostTo(_pRho);
153 EvtVector4R _p3( _ee(_mRho, m2, m3), 0., 0., -__ppPi); _p3.applyBoostTo(_pRho);
154 p->getDaug(1)->setP4(_p2);
155 p->getDaug(2)->setP4(_p3);
156
157 }
158 else if( getNDaug()==4) {
159 double M=EvtPDL::getMass(id),
160 m1=EvtPDL::getMass(getDaug(0)),
161 m2=EvtPDL::getMass(getDaug(1)),
162 m3=EvtPDL::getMass(getDaug(2)),
163 m4=EvtPDL::getMass(getDaug(3));
164 if(M<m1+_mA1) return;
165 double __ppA1=_pp(M,m1,_mA1),
166 __ppRho=_pp(_mA1,_mRho,m4),
167 __ppPi=_pp(_mRho, m2, m3);
168 p->getDaug(0)->setP4( EvtVector4R( _ee(M,m1,_mRho), 0., 0., __ppA1) );
169 EvtVector4R _pA1( _ee(M,_mA1,m1), 0., 0., -__ppA1);
170 EvtVector4R _pRho(_ee(_mA1, _mRho, m4), 0, 0, __ppRho);
171 _pRho.applyBoostTo(_pA1);
172 EvtVector4R _p4( _ee(_mA1, m4, _mRho), 0, 0, -__ppRho); _p4.applyBoostTo(_pA1);
173 p->getDaug(3)->setP4(_p4);
174 EvtVector4R _p2( _ee(_mRho, m2, m3), 0, 0, __ppPi); _p2.applyBoostTo(_pRho);
175 p->getDaug(1)->setP4(_p2);
176 EvtVector4R _p3( _ee(_mRho, m2, m3), 0, 0, -__ppPi); _p2.applyBoostTo(_pRho);
177 p->getDaug(2)->setP4(_p3);
178 };
179
180
181 _amp2.init(p->getId(),getNDaug(),getDaugs());
182
183 decay(p);
184
185 EvtSpinDensity rho=_amp2.getSpinDensity();
186
187 double prob=p->getSpinDensityForward().normalizedProb(rho);
188
189 if(prob>0) setProbMax(0.9*prob);
190
191
192 };
193}
194
195void EvtBcToNPi::decay( EvtParticle *root_particle ){
196 ++nCall;
197
198 EvtIdSet thePis("pi+","pi-","pi0");
199 EvtComplex I=EvtComplex(0.0, 1.0);
200
201
202 root_particle->initializePhaseSpace(getNDaug(),getDaugs());
203
204 EvtVector4R
205 p(root_particle->mass(), 0., 0., 0.), // Bc momentum
206 k=root_particle->getDaug(0)->getP4(), // J/psi momenta
207 Q=p-k;
208
209 double Q2=Q.mass2();
210
211
212// check pi-mesons and calculate hadronic current
213 EvtVector4C hardCur;
214 bool foundHadCurr=false;
215
216 if ( getNDaug() == 2 ) // Bc -> psi pi+
217 {
218 hardCur=Q;
219 foundHadCurr=true;
220 }
221 else if ( getNDaug() == 3 ) // Bc -> psi pi+ pi0
222 {
223 EvtVector4R p1,p2;
224 p1=root_particle->getDaug(1)->getP4(), // pi+ momenta
225 p2=root_particle->getDaug(2)->getP4(), // pi0 momentum
226 hardCur=Fpi(p1,p2)*(p1-p2);
227 foundHadCurr=true;
228 }
229 else if( getNDaug()==4 ) // Bc -> psi pi+ pi pi
230 {
231 int diffPi(0),samePi1(0),samePi2(0);
232 if ( getDaug( 1) == getDaug( 2) ) {diffPi= 3; samePi1= 1; samePi2= 2;}
233 if ( getDaug( 1) == getDaug( 3) ) {diffPi= 2; samePi1= 1; samePi2= 3;}
234 if ( getDaug( 2) == getDaug( 3) ) {diffPi= 1; samePi1= 2; samePi2= 3;}
235
236 EvtVector4R p1=root_particle->getDaug(samePi1)->getP4();
237 EvtVector4R p2=root_particle->getDaug(samePi2)->getP4();
238 EvtVector4R p3=root_particle->getDaug(diffPi)->getP4();
239
240 EvtComplex BA1;
241 double GA1=_gammaA1*pi3G(Q2,samePi1)/pi3G(_mA1*_mA1,samePi1);
242 EvtComplex denBA1(_mA1*_mA1 - Q.mass2(),-1.*_mA1*GA1);
243 BA1 = _mA1*_mA1 / denBA1;
244
245 hardCur = BA1*( (p1-p3) - (Q*(Q*(p1-p3))/Q2)*Fpi(p2,p3) +
246 (p2-p3) - (Q*(Q*(p2-p3))/Q2)*Fpi(p1,p3) );
247 foundHadCurr=true;
248 }
249
250 if ( !foundHadCurr ) {
251 report(ERROR,"EvtGen") << "Have not yet implemented this final state in BCNPI model" << endl;
252 report(ERROR,"EvtGen") << "Ndaug="<<getNDaug() << endl;
253 int id;
254 for ( id=0; id<(getNDaug()-1); id++ )
255 report(ERROR,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
256 ::abort();
257 };
258
259 EvtTensor4C H;
260 double amp2=0.;
261 if( root_particle->getDaug(0)->getSpinType() == EvtSpinType::VECTOR) {
262 double FA0=FA0_N*exp(FA0_c1*Q2 + FA0_c2*Q2*Q2);
263 double FAp=FAp_N*exp(FAp_c1*Q2 + FAp_c2*Q2*Q2);
264 double FAm=FAm_N*exp(FAm_c1*Q2 + FAm_c2*Q2*Q2);
265 double FV= FV_N* exp( FV_c1*Q2 + FV_c2*Q2*Q2 );
266 H=-FA0*EvtTensor4C::g()
267 -FAp*EvtGenFunctions::directProd(p,p+k)
268 +FAm*EvtGenFunctions::directProd(p,p-k)
269 +2*I*FV*dual(EvtGenFunctions::directProd(p,k));
270 EvtVector4C Heps=H.cont2(hardCur);
271
272 for(int i=0; i<4; i++) {
273 EvtVector4C eps=root_particle->getDaug(0)->epsParent(i).conj(); // psi-meson polarization vector
274 EvtComplex amp=eps*Heps;
275 vertex(i,amp);
276 amp2+=pow( abs(amp),2);
277 }
278 }
279 else if( root_particle->getDaug(0)->getSpinType() == EvtSpinType::SCALAR) {
280 double Fp=Fp_N*exp(Fp_c1*Q2 + Fp_c2*Q2*Q2);
281 double Fm=Fm_N*exp(Fm_c1*Q2 + Fm_c2*Q2*Q2);
282 EvtVector4C H=Fp*(p+k)+Fm*(p-k);
283 EvtComplex amp=H*hardCur;
284 vertex(amp);
285 amp2+=pow( abs(amp),2);
286 };
287 if(amp2>maxAmp2) maxAmp2=amp2;
288
289 return ;
290}
291
292EvtComplex EvtBcToNPi::Fpi( EvtVector4R q1, EvtVector4R q2) {
293 double m1=q1.mass();
294 double m2=q2.mass();
295
296 EvtVector4R Q = q1 + q2;
297 double mQ2= Q*Q;
298
299 // momenta in the rho->pipi decay
300 double dRho= _mRho*_mRho - m1*m1 - m2*m2;
301 double pPiRho = (1.0/_mRho)*sqrt((dRho*dRho)/4.0 - m1*m1*m2*m2);
302
303 double dRhopr= _mRhopr*_mRhopr - m1*m1 - m2*m2;
304 double pPiRhopr = (1.0/_mRhopr)*sqrt((dRhopr*dRhopr)/4.0 - m1*m1*m2*m2);
305
306 double dQ= mQ2 - m1*m1 - m2*m2;
307 double pPiQ = (1.0/sqrt(mQ2))*sqrt((dQ*dQ)/4.0 - m1*m1*m2*m2);
308
309
310 double gammaRho = _gammaRho*_mRho/sqrt(mQ2)*pow((pPiQ/pPiRho),3);
311 EvtComplex BRhoDem(_mRho*_mRho - mQ2,-1.0*_mRho*gammaRho);
312 EvtComplex BRho= _mRho*_mRho / BRhoDem;
313
314 double gammaRhopr = _gammaRhopr*_mRhopr/sqrt(mQ2)*pow((pPiQ/pPiRhopr),3);
315 EvtComplex BRhoprDem(_mRhopr*_mRhopr - mQ2,-1.0*_mRho*gammaRhopr);
316 EvtComplex BRhopr= _mRhopr*_mRhopr / BRhoprDem;
317
318 return (BRho + _beta*BRhopr)/(1+_beta);
319}
320
321double EvtBcToNPi::pi3G(double m2,int dupD) {
322 double mPi= EvtPDL::getMeanMass(getDaug(dupD));
323 if ( m2 > (_mRho+mPi) ) {
324 return m2*(1.623 + 10.38/m2 - 9.32/(m2*m2) + 0.65/(m2*m2*m2));
325 }
326 else {
327 double t1=m2-9.0*mPi*mPi;
328 return 4.1*pow(t1,3.0)*(1.0 - 3.3*t1+5.8*t1*t1);
329 }
330}
331
332void EvtBcToNPi::printAuthorInfo() {
333
334 report(INFO,"EvtGen")<<"Defining EvtBcToNPi model: Bc -> V + npi and Bc -> P + npi decays\n"
335 <<"from A.V. Berezhnoy, A.K. Likhoded, A.V. Luchinsky: "
336 <<"Phys.Rev.D 82, 014012 (2010) and arXiV:1104.0808."<<endl;
337
338}
339