Fix bug in building local list of valid files.
[u/mrichter/AliRoot.git] / TEvtGen / EvtGenModels / EvtBBScalar.cpp
CommitLineData
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) 2003 Caltech
10//
11// Module: EvtGen/EvtBBScalar
12//
13// Description:Implementation of the decay B- -> lambda p_bar pi according to
14// hep-ph/0204185, hep-ph/0211240
15// This model is intended to be applicable to all decays of the type B-> baryon baryon scalar
16//
17// Modification history:
18//
19// Jan Strube March 24, 2006 Module created
20//
21//------------------------------------------------------------------------
22#include "EvtGenBase/EvtPatches.hh"
23
24#include "EvtGenModels/EvtBBScalar.hh"
25#include "EvtGenBase/EvtGammaMatrix.hh"
26#include "EvtGenBase/EvtDiracSpinor.hh"
27#include "EvtGenBase/EvtSpinType.hh"
28#include "EvtGenBase/EvtTensor4C.hh"
29#include <cmath>
30
31using namespace std;
32
33const float pi = 3.14159;
34const EvtComplex EvtBBScalar::I = EvtComplex(0, 1);
35const EvtComplex EvtBBScalar::V_ub = EvtComplex(3.67e-3*cos(60/180*pi), 3.67e-3*cos(60/180*pi));
36const EvtComplex EvtBBScalar::V_us_star = EvtComplex(0.22, 0);
37const EvtComplex EvtBBScalar::a1 = EvtComplex(1.05, 0);
38const EvtComplex EvtBBScalar::V_tb = EvtComplex(0.99915, 0);
39const EvtComplex EvtBBScalar::V_ts_star = EvtComplex(-0.04029-0.000813*cos(60/180*pi), -0.000813*cos(60/180*pi));
40const EvtComplex EvtBBScalar::a4 = EvtComplex(-387.3e-4, -121e-4);
41const EvtComplex EvtBBScalar::a6 = EvtComplex(-555.3e-4, -121e-4);
42const double EvtBBScalar::x[] = {420.96, -10485.50, 100639.97, -433916.61, 613780.15};
43const double EvtBBScalar::y[] = {292.62, -735.73};
44const double EvtBBScalar::m_s = 0.120;
45const double EvtBBScalar::m_u = 0.029 * 0.120;
46const double EvtBBScalar::m_b = 4.88;
47
48
49EvtBBScalar::EvtBBScalar()
50 : EvtDecayAmp()
51 , _massRatio(0)
52 , _baryonMassSum(0)
53{
54 FormFactor dummy;
55 dummy.value = 0.36;
56 dummy.sigma1 = 0.43;
0ca57c2f 57 dummy.sigma2 = 0.0;
da0e9ce3 58 dummy.mV = 5.42;
59 _f1Map.insert(make_pair(string("K"), dummy));
60 dummy.sigma1 = 0.70;
61 dummy.sigma2 = 0.27;
62 _f0Map.insert(make_pair(string("K"), dummy));
63 dummy.value = 0.29;
64 dummy.sigma1 = 0.48;
65 dummy.sigma2 = 0.0;
66 dummy.mV = 5.32;
67 _f1Map.insert(make_pair(string("pi"), dummy));
68 dummy.sigma1 = 0.76;
69 dummy.sigma2 = 0.28;
70 _f0Map.insert(make_pair(string("pi"), dummy));
71}
72
73
74
75std::string EvtBBScalar::getName(){
76 return "B_TO_2BARYON_SCALAR";
77}
78
79EvtDecayBase* EvtBBScalar::clone(){
80 return new EvtBBScalar;
81}
82
83
84void EvtBBScalar::setKnownBaryonTypes(const EvtId& baryon) {
85 int baryonId = EvtPDL::getStdHep(baryon);
86 if (EvtPDL::getStdHep(EvtPDL::getId("Lambda0")) == baryonId
87 or EvtPDL::getStdHep(EvtPDL::getId("anti-Lambda0")) == baryonId ) {
88 _baryonCombination.set(Lambda);
89 } else if (EvtPDL::getStdHep(EvtPDL::getId("p+")) == baryonId
90 or EvtPDL::getStdHep(EvtPDL::getId("anti-p-")) == baryonId ) {
91 _baryonCombination.set(Proton);
92 } else if (EvtPDL::getStdHep(EvtPDL::getId("n0")) == baryonId
93 or EvtPDL::getStdHep(EvtPDL::getId("anti-n0")) == baryonId) {
94 _baryonCombination.set(Neutron);
95 } else if (EvtPDL::getStdHep(EvtPDL::getId("Sigma0")) == baryonId
96 or EvtPDL::getStdHep(EvtPDL::getId("anti-Sigma0")) == baryonId ) {
97 _baryonCombination.set(Sigma0);
98 } else if (EvtPDL::getStdHep(EvtPDL::getId("Sigma-")) == baryonId
99 or EvtPDL::getStdHep(EvtPDL::getId("anti-Sigma+")) == baryonId ) {
100 _baryonCombination.set(Sigma_minus);
101 } else if (EvtPDL::getStdHep(EvtPDL::getId("Xi0")) == baryonId
102 or EvtPDL::getStdHep(EvtPDL::getId("anti-Xi0")) == baryonId) {
103 _baryonCombination.set(Xi0);
104 } else if (EvtPDL::getStdHep(EvtPDL::getId("Xi-")) == baryonId
105 or EvtPDL::getStdHep(EvtPDL::getId("anti-Xi+")) == baryonId) {
106 _baryonCombination.set(Xi_minus);
107 } else {
108 report(ERROR, "EvtGen")
109 << "EvtBBScalar::init: Don't know what to do with this type as the first or second baryon\n";
110 exit(2);
111 }
112}
113
0ca57c2f 114double EvtBBScalar::baryonF1F2(double t) const {
da0e9ce3 115 // check for known form factors for combination of baryons
116 if (_baryonCombination.test(Lambda) and _baryonCombination.test(Proton)) {
117 return -sqrt(1.5) * G_p(t);
118 } else if (_baryonCombination.test(Sigma0) and _baryonCombination.test(Proton)) {
119 return -sqrt(0.5) * (G_p(t) + 2* G_n(t));
120 } else if (_baryonCombination.test(Sigma_minus) and _baryonCombination.test(Neutron)) {
121 return -G_p(t) - 2* G_n(t);
122 } else if (_baryonCombination.test(Xi0) and _baryonCombination.test(Sigma_minus)) {
123 return G_p(t) - G_n(t);
124 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Sigma0)) {
125 return sqrt(0.5) * (G_p(t) - G_n(t));
126 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Lambda)) {
127 return sqrt(1.5) * (G_p(t) + G_n(t));
128 } else {
129 report(ERROR, "EvtGen")
130 << "EvtBBScalar::baryonF1F2: Don't know what to do with this type as the first or second baryon\n";
131 exit(2);
132 }
133}
134
0ca57c2f 135double EvtBBScalar::formFactorFit(double t, const vector<double>& params) const {
da0e9ce3 136 static const double gamma = 2.148;
137 static const double Lambda_0 = 0.3;
138 double result = 0;
139 for (size_t i=0; i<params.size(); ++i) {
140 result += params[i]/pow(t, static_cast<int>(i+1));
141 }
142 return result * pow(log(t/pow(Lambda_0, 2)), -gamma);
143}
144
145
0ca57c2f 146double EvtBBScalar::G_p(double t) const {
da0e9ce3 147 const vector<double> v_x(x, x+5);
148 return formFactorFit(t, v_x);
149}
150
0ca57c2f 151double EvtBBScalar::G_n(double t) const {
da0e9ce3 152 const vector<double> v_y(y, y+2);
153 return -formFactorFit(t, v_y);
154}
155
0ca57c2f 156double EvtBBScalar::baryon_gA(double t) const {
da0e9ce3 157 // check for known form factors for combination of baryons
158 if (_baryonCombination.test(Lambda) and _baryonCombination.test(Proton)) {
159 return -1/sqrt(6.) * (D_A(t) + 3*F_A(t));
160 } else if (_baryonCombination.test(Sigma0) and _baryonCombination.test(Proton)) {
161 return 1/sqrt(2.) * (D_A(t) - F_A(t));
162 } else if (_baryonCombination.test(Sigma_minus) and _baryonCombination.test(Neutron)) {
163 return D_A(t) - F_A(t);
164 } else if (_baryonCombination.test(Xi0) and _baryonCombination.test(Sigma_minus)) {
165 return D_A(t) + F_A(t);
166 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Sigma0)) {
167 return 1/sqrt(2.) * (D_A(t) + F_A(t));
168 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Lambda)) {
169 return -1 / sqrt(6.) * (D_A(t) - 3*F_A(t));
170 } else {
171 report(ERROR, "EvtGen")
172 << "EvtBBScalar::baryon_gA: Don't know what to do with this type as the first or second baryon\n";
173 exit(2);
174 }
175}
176
0ca57c2f 177double EvtBBScalar::baryon_gP(double t) const {
da0e9ce3 178 // check for known form factors for combination of baryons
179 if (_baryonCombination.test(Lambda) and _baryonCombination.test(Proton)) {
180 return -1/sqrt(6.) * (D_P(t) + 3*F_P(t));
181 } else if (_baryonCombination.test(Sigma0) and _baryonCombination.test(Proton)) {
182 return 1/sqrt(2.) * (D_P(t) - F_P(t));
183 } else if (_baryonCombination.test(Sigma_minus) and _baryonCombination.test(Neutron)) {
184 return D_P(t) - F_P(t);
185 } else if (_baryonCombination.test(Xi0) and _baryonCombination.test(Sigma_minus)) {
186 return D_P(t) + F_P(t);
187 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Sigma0)) {
188 return 1/sqrt(2.) * (D_P(t) + F_P(t));
189 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Lambda)) {
190 return -1 / sqrt(6.) * (D_P(t) - 3*F_P(t));
191 } else {
192 report(ERROR, "EvtGen")
193 << "EvtBBScalar::baryon_gP: Don't know what to do with this type as the first or second baryon\n";
194 exit(2);
195 }
196}
197
0ca57c2f 198double EvtBBScalar::baryon_fS(double t) const {
da0e9ce3 199 // check for known form factors for combination of baryons
200 if (_baryonCombination.test(Lambda) and _baryonCombination.test(Proton)) {
201 return -1/sqrt(6.) * (D_S(t) + 3*F_S(t));
202 } else if (_baryonCombination.test(Sigma0) and _baryonCombination.test(Proton)) {
203 return 1/sqrt(2.) * (D_S(t) - F_S(t));
204 } else if (_baryonCombination.test(Sigma_minus) and _baryonCombination.test(Neutron)) {
205 return D_S(t) - F_S(t);
206 } else if (_baryonCombination.test(Xi0) and _baryonCombination.test(Sigma_minus)) {
207 return D_S(t) + F_S(t);
208 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Sigma0)) {
209 return 1/sqrt(2.) * (D_S(t) + F_S(t));
210 } else if (_baryonCombination.test(Xi_minus) and _baryonCombination.test(Lambda)) {
211 return -1 / sqrt(6.) * (D_S(t) - 3*F_S(t));
212 } else {
213 report(ERROR, "EvtGen")
214 << "EvtBBScalar::baryon_fS: Don't know what to do with this type as the first or second baryon\n";
215 exit(2);
216 }
217}
218
0ca57c2f 219double EvtBBScalar::D_A(double t) const {
da0e9ce3 220 const double d_tilde[] = {x[0]-1.5*y[0], -478};
221 const vector<double> v_d_tilde(d_tilde, d_tilde+2);
222 return formFactorFit(t, v_d_tilde);
223}
224
0ca57c2f 225double EvtBBScalar::F_A(double t) const {
da0e9ce3 226 const double f_tilde[] = {2./3*x[0]+0.5*y[0], -478};
227 const vector<double> v_f_tilde(f_tilde, f_tilde+2);
228 return formFactorFit(t, v_f_tilde);
229}
230
0ca57c2f 231double EvtBBScalar::D_P(double t) const {
da0e9ce3 232 const double d_bar[] = {1.5*y[0]* _massRatio, /*-952*/0};
233 const vector<double> v_d_bar(d_bar, d_bar+2);
234 return formFactorFit(t, v_d_bar);
235}
236
0ca57c2f 237double EvtBBScalar::F_P(double t) const {
da0e9ce3 238 const double f_bar[] = {(x[0]-0.5*y[0]) * _massRatio, /*-952*/0};
239 const vector<double> v_f_bar(f_bar, f_bar+2);
240 return formFactorFit(t, v_f_bar);
241}
242
0ca57c2f 243double EvtBBScalar::D_S(double t) const {
da0e9ce3 244 return -1.5 * _massRatio * G_n(t);
245}
246
0ca57c2f 247double EvtBBScalar::F_S(double t) const {
da0e9ce3 248 return (G_p(t) + 0.5*G_n(t)) * _massRatio;
249}
250
0ca57c2f 251double EvtBBScalar::baryon_hA(double t) const {
da0e9ce3 252 return (1/_massRatio*baryon_gP(t)-baryon_gA(t))*pow(_baryonMassSum, 2)/t;
253}
254
255
256void EvtBBScalar::init() {
257 // no arguments, daughter lambda p_bar pi
258 // charge conservation is checked by base class
259 checkNArg(0);
260 checkNDaug(3);
261 checkSpinParent(EvtSpinType::SCALAR);
262 checkSpinDaughter(0, EvtSpinType::DIRAC);
263 checkSpinDaughter(1, EvtSpinType::DIRAC);
264 checkSpinDaughter(2, EvtSpinType::SCALAR);
265 EvtId baryon1 = getDaug(0);
266 EvtId baryon2 = getDaug(1);
267 EvtId scalar = getDaug(2);
268 int scalarId = EvtPDL::getStdHep(scalar);
269
270 // Different form factors for the B-pi or B-K transition.
271 if ( scalarId == EvtPDL::getStdHep(EvtPDL::getId("pi+"))
272 or scalarId == EvtPDL::getStdHep(EvtPDL::getId("pi-"))
273 or scalarId == EvtPDL::getStdHep(EvtPDL::getId("pi0"))) {
274 _scalarType = "pi";
275 } else if (scalarId == EvtPDL::getStdHep(EvtPDL::getId("K+"))
276 or scalarId == EvtPDL::getStdHep(EvtPDL::getId("K-"))
277 or scalarId == EvtPDL::getStdHep(EvtPDL::getId("K0"))
278 or scalarId == EvtPDL::getStdHep(EvtPDL::getId("anti-K0"))) {
279 _scalarType = "K";
280 } else {
281 report(ERROR, "EvtGen")
282 << "EvtBBScalar::init: Can only deal with Kaons or pions as the third particle\n"
283 << "\tFound: " << scalarId << endl;
284 exit(2);
285 }
286 // check for known particles
287 setKnownBaryonTypes(baryon1);
288 setKnownBaryonTypes(baryon2);
289 double mass1 = EvtPDL::getMass(baryon1);
290 double mass2 = EvtPDL::getMass(baryon2);
291 // This whole model deals only with baryons that differ in s-u
292 if (mass1 > mass2)
293 _massRatio = (mass1-mass2) / (m_s-m_u);
294 else
295 _massRatio = (mass2-mass1) / (m_s-m_u);
296 _baryonMassSum = mass1 + mass2;
297}
298
299
300// initialize phasespace and calculate the amplitude
301void EvtBBScalar::decay(EvtParticle* p) {
302 p->initializePhaseSpace(getNDaug(), getDaugs());
303 EvtVector4R B_Momentum = p->getP4Lab();
304 EvtDiracParticle* theLambda = dynamic_cast<EvtDiracParticle*>(p->getDaug(0));
305 EvtDiracParticle* theAntiP = dynamic_cast<EvtDiracParticle*>(p->getDaug(1));
306 EvtScalarParticle* theScalar = dynamic_cast<EvtScalarParticle*>(p->getDaug(2));
307 EvtVector4R scalarMomentum = theScalar->getP4Lab();
308
309 // The amplitude consists of three matrix elements. These will be calculated one by one here.
310
311 // loop over all possible spin states
312 for (int i=0; i<2; ++i) {
313 EvtDiracSpinor lambdaPol = theLambda->spParent(i);
314 for (int j=0; j<2; ++j) {
315 EvtDiracSpinor antiP_Pol = theAntiP->spParent(j);
316 EvtVector4C theAmplitudePartA = amp_A(B_Momentum, scalarMomentum);
317 EvtComplex amplitude;
318 for (int index=0; index<4; ++index) {
319 amplitude += theAmplitudePartA.get(index)
320 * ( const_B*amp_B(theLambda, lambdaPol, theAntiP, antiP_Pol, index)
321 + const_C*amp_C(theLambda, lambdaPol, theAntiP, antiP_Pol, index) );
322 }
323 vertex(i, j, amplitude);
324 }
325 }
326}
327
328void EvtBBScalar::initProbMax()
329{
330 // setProbMax(1);
331 setProbMax(0.2); // found by trial and error
332}
333
334// Form factor f1 for B-pi transition
0ca57c2f 335double EvtBBScalar::B_pi_f1(double t) const
da0e9ce3 336{
337 FormFactor f = _f1Map[_scalarType];
338 double mv2 = f.mV*f.mV;
339 return f.value / ((1-t/mv2) * (1-f.sigma1*t/mv2+f.sigma2*t*t/mv2/mv2));
340}
341
342// Form factor f0 for B-pi transition
0ca57c2f 343double EvtBBScalar::B_pi_f0(double t) const
da0e9ce3 344{
345 FormFactor f = _f0Map[_scalarType];
346 double mv2 = f.mV*f.mV;
347 return f.value / (1 - f.sigma1*t/mv2 + f.sigma2*t*t/mv2/mv2);
348}
349
da0e9ce3 350// constants of the B and C parts of the amplitude
351const EvtComplex EvtBBScalar::const_B = V_ub*V_us_star*a1 - V_tb*V_ts_star*a4;
352const EvtComplex EvtBBScalar::const_C = 2*a6*V_tb*V_ts_star;
353
354// part A of the amplitude, see hep-ph/0204185
355const EvtVector4C
356EvtBBScalar::amp_A(const EvtVector4R& p4B, const EvtVector4R& p4Scalar)
357{
358 double mB2 = p4B.mass2();
359 double mScalar2 = p4Scalar.mass2();
360 double t = (p4B-p4Scalar).mass2();
361 return ((p4B+p4Scalar) - (mB2-mScalar2)/t * (p4B-p4Scalar)) * B_pi_f1(t)
362 + (mB2-mScalar2)/t * (p4B-p4Scalar) * B_pi_f0(t);
363}
364
365// part B of the amplitude, Vector and Axial Vector parts
366const EvtComplex
367EvtBBScalar::amp_B(const EvtDiracParticle* baryon1, const EvtDiracSpinor& b1Pol
368 , const EvtDiracParticle* baryon2, const EvtDiracSpinor& b2Pol
369 , int index)
370{
371 return amp_B_vectorPart(baryon1, b1Pol, baryon2, b2Pol, index)
372 - amp_B_axialPart(baryon1, b1Pol, baryon2, b2Pol, index);
373}
374
375
376const EvtComplex
377EvtBBScalar::amp_B_vectorPart(const EvtDiracParticle* baryon1, const EvtDiracSpinor& b1Pol
378 , const EvtDiracParticle* baryon2, const EvtDiracSpinor& b2Pol
379 , int index)
380{
381 double t = (baryon1->getP4Lab() + baryon2->getP4Lab()).mass2();
382 EvtGammaMatrix gamma;
383 for (int i=0; i<4; ++i) {
384 gamma += EvtTensor4C::g().get(index, i) * EvtGammaMatrix::g(i);
385 }
386 // The F2 contribution that is written out in the paper is neglected here.
387 // see hep-ph/0204185
0ca57c2f 388 EvtDiracSpinor A = EvtComplex(baryonF1F2(t))*b2Pol ;
389 EvtDiracSpinor Adjb1Pol = b1Pol.adjoint() ;
390 EvtDiracSpinor gammaA = gamma * A ;
391 return Adjb1Pol * gammaA ;
392 // return b1Pol.adjoint()*(gamma*(EvtComplex(baryonF1F2(t))*b2Pol));
da0e9ce3 393}
394
395const EvtComplex
396EvtBBScalar::amp_B_axialPart(const EvtDiracParticle* baryon1, const EvtDiracSpinor& b1Pol
397 , const EvtDiracParticle* baryon2, const EvtDiracSpinor& b2Pol
398 , int index)
399{
400 EvtGammaMatrix gamma;
401 for (int i=0; i<4; ++i) {
402 gamma += EvtTensor4C::g().get(index, i) * EvtGammaMatrix::g(i);
403 }
404 double t = (baryon1->getP4Lab() + baryon2->getP4Lab()).mass2();
405 double mSum = baryon1->mass() + baryon2->mass();
406 EvtVector4C momentum_upper = (baryon1->getP4Lab()+baryon2->getP4Lab());
407 EvtVector4C momentum;
408 for (int mu=0; mu<0; ++mu) {
409 EvtComplex dummy;
410 for (int i=0; i<4; ++i) {
411 dummy += EvtTensor4C::g().get(index, i)*momentum_upper.get(i);
412 }
413 momentum.set(mu, dummy);
414 }
415 return b1Pol.adjoint() * (((baryon_gA(t) * gamma +
416 EvtGammaMatrix::id()*baryon_hA(t)/mSum*momentum.get(index))
417 * EvtGammaMatrix::g5()) * b2Pol);
418}
419
420
421// part C of the amplitude, Scalar and Pseudoscalar parts
422const EvtComplex
423EvtBBScalar::amp_C(const EvtDiracParticle* baryon1, const EvtDiracSpinor& b1Pol
424 , const EvtDiracParticle* baryon2, const EvtDiracSpinor& b2Pol
425 , int index)
426{
427 EvtVector4C baryonSumP4_upper = baryon1->getP4Lab() + baryon2->getP4Lab();
428 EvtVector4C baryonSumP4;
429 for (int mu=0; mu<4; ++mu) {
430 EvtComplex dummy;
431 for (int i=0; i<4; ++i) {
432 dummy += EvtTensor4C::g().get(mu, i) * baryonSumP4_upper.get(i);
433 }
434 baryonSumP4.set(mu, dummy);
435 }
436 double t = (baryon1->getP4Lab() + baryon2->getP4Lab()).mass2();
437 return baryonSumP4.get(index)/(m_b-m_u)*(amp_C_scalarPart(b1Pol, b2Pol, t) + amp_C_pseudoscalarPart(b1Pol, b2Pol, t));
438}
439
440
441const EvtComplex
442EvtBBScalar::amp_C_scalarPart(const EvtDiracSpinor& b1Pol, const EvtDiracSpinor& b2Pol, double t)
443{
444 return baryon_fS(t) * b1Pol.adjoint()*b2Pol;
445}
446
447const EvtComplex
448EvtBBScalar::amp_C_pseudoscalarPart(const EvtDiracSpinor& b1Pol, const EvtDiracSpinor& b2Pol, double t)
449{
450 return baryon_gP(t) * b1Pol.adjoint()*(EvtGammaMatrix::g5()*b2Pol);
451}
452