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26 // $Id: G4ANuTauNucleusCcModel.cc 91806 2015-08-06 12:20:45Z gcosmo $
27 //
28 // Geant4 Header : G4ANuTauNucleusCcModel
29 //
30 // Author : V.Grichine 12.2.19
31 //
32
33 #include <iostream>
34 #include <fstream>
35 #include <sstream>
36
37 #include "G4ANuTauNucleusCcModel.hh"
38 // #include "G4NuMuNuclCcDistrKR.hh"
39
40 // #include "G4NuMuResQX.hh"
41
42 #include "G4SystemOfUnits.hh"
43 #include "G4ParticleTable.hh"
44 #include "G4ParticleDefinition.hh"
45 #include "G4IonTable.hh"
46 #include "Randomize.hh"
47 #include "G4RandomDirection.hh"
48 // #include "G4Threading.hh"
49
50 // #include "G4Integrator.hh"
51 #include "G4DataVector.hh"
52 #include "G4PhysicsTable.hh"
53 /*
54 #include "G4CascadeInterface.hh"
55 // #include "G4BinaryCascade.hh"
56 #include "G4TheoFSGenerator.hh"
57 #include "G4LundStringFragmentation.hh"
58 #include "G4ExcitedStringDecay.hh"
59 #include "G4FTFModel.hh"
60 // #include "G4BinaryCascade.hh"
61 #include "G4HadFinalState.hh"
62 #include "G4HadSecondary.hh"
63 #include "G4HadronicInteractionRegistry.hh"
64 // #include "G4INCLXXInterface.hh"
65 #include "G4QGSModel.hh"
66 #include "G4QGSMFragmentation.hh"
67 #include "G4QGSParticipants.hh"
68 */
69 #include "G4KineticTrack.hh"
70 #include "G4DecayKineticTracks.hh"
71 #include "G4KineticTrackVector.hh"
72 #include "G4Fragment.hh"
73 #include "G4NucleiProperties.hh"
74 #include "G4ReactionProductVector.hh"
75
76 #include "G4GeneratorPrecompoundInterface.hh"
77 #include "G4PreCompoundModel.hh"
78 #include "G4ExcitationHandler.hh"
79
80
81 #include "G4TauMinus.hh"
82 #include "G4TauPlus.hh"
83 #include "G4Nucleus.hh"
84 #include "G4LorentzVector.hh"
85
86 using namespace std;
87 using namespace CLHEP;
88
89 #ifdef G4MULTITHREADED
90 G4Mutex G4ANuTauNucleusCcModel::numuNucleusModel = G4MUTEX_INITIALIZER;
91 #endif
92
93
94 G4ANuTauNucleusCcModel::G4ANuTauNucleusCcModel(const G4String& name)
95 : G4NeutrinoNucleusModel(name)
96 {
97 fData = fMaster = false;
98 fMtau = 1.77686*GeV;
99 theTauMinus = G4TauMinus::TauMinus();
100 theTauPlus = G4TauPlus::TauPlus();
101 InitialiseModel();
102 }
103
104
105 G4ANuTauNucleusCcModel::~G4ANuTauNucleusCcModel()
106 {}
107
108
109 void G4ANuTauNucleusCcModel::ModelDescription(std::ostream& outFile) const
110 {
111
112 outFile << "G4ANuTauNucleusCcModel is a anti tau neutrino-nucleus (charge current) scattering\n"
113 << "model which uses the standard model \n"
114 << "transfer parameterization. The model is fully relativistic\n";
115
116 }
117
118 /////////////////////////////////////////////////////////
119 //
120 // Read data from G4PARTICLEXSDATA (locally PARTICLEXSDATA)
121
122 void G4ANuTauNucleusCcModel::InitialiseModel()
123 {
124 G4String pName = "nu_mu";
125 // G4String pName = "anti_nu_mu";
126
127 G4int nSize(0), i(0), j(0), k(0);
128
129 if(!fData)
130 {
131 #ifdef G4MULTITHREADED
132 G4MUTEXLOCK(&numuNucleusModel);
133 if(!fData)
134 {
135 #endif
136 fMaster = true;
137 #ifdef G4MULTITHREADED
138 }
139 G4MUTEXUNLOCK(&numuNucleusModel);
140 #endif
141 }
142
143 if(fMaster)
144 {
145 const char* path = G4FindDataDir("G4PARTICLEXSDATA");
146 std::ostringstream ost1, ost2, ost3, ost4;
147 ost1 << path << "/" << "neutrino" << "/" << pName << "/xarraycckr";
148
149 std::ifstream filein1( ost1.str().c_str() );
150
151 // filein.open("$PARTICLEXSDATA/");
152
153 filein1>>nSize;
154
155 for( k = 0; k < fNbin; ++k )
156 {
157 for( i = 0; i <= fNbin; ++i )
158 {
159 filein1 >> fNuMuXarrayKR[k][i];
160 // G4cout<< fNuMuXarrayKR[k][i] << " ";
161 }
162 }
163 // G4cout<<G4endl<<G4endl;
164
165 ost2 << path << "/" << "neutrino" << "/" << pName << "/xdistrcckr";
166 std::ifstream filein2( ost2.str().c_str() );
167
168 filein2>>nSize;
169
170 for( k = 0; k < fNbin; ++k )
171 {
172 for( i = 0; i < fNbin; ++i )
173 {
174 filein2 >> fNuMuXdistrKR[k][i];
175 // G4cout<< fNuMuXdistrKR[k][i] << " ";
176 }
177 }
178 // G4cout<<G4endl<<G4endl;
179
180 ost3 << path << "/" << "neutrino" << "/" << pName << "/q2arraycckr";
181 std::ifstream filein3( ost3.str().c_str() );
182
183 filein3>>nSize;
184
185 for( k = 0; k < fNbin; ++k )
186 {
187 for( i = 0; i <= fNbin; ++i )
188 {
189 for( j = 0; j <= fNbin; ++j )
190 {
191 filein3 >> fNuMuQarrayKR[k][i][j];
192 // G4cout<< fNuMuQarrayKR[k][i][j] << " ";
193 }
194 }
195 }
196 // G4cout<<G4endl<<G4endl;
197
198 ost4 << path << "/" << "neutrino" << "/" << pName << "/q2distrcckr";
199 std::ifstream filein4( ost4.str().c_str() );
200
201 filein4>>nSize;
202
203 for( k = 0; k < fNbin; ++k )
204 {
205 for( i = 0; i <= fNbin; ++i )
206 {
207 for( j = 0; j < fNbin; ++j )
208 {
209 filein4 >> fNuMuQdistrKR[k][i][j];
210 // G4cout<< fNuMuQdistrKR[k][i][j] << " ";
211 }
212 }
213 }
214 fData = true;
215 }
216 }
217
218 /////////////////////////////////////////////////////////
219
220 G4bool G4ANuTauNucleusCcModel::IsApplicable(const G4HadProjectile & aPart,
221 G4Nucleus & )
222 {
223 G4bool result = false;
224 G4String pName = aPart.GetDefinition()->GetParticleName();
225 G4double energy = aPart.GetTotalEnergy();
226
227 if( pName == "anti_nu_tau" // || pName == "anti_nu_tau" )
228 &&
229 energy > fMinNuEnergy )
230 {
231 result = true;
232 }
233
234 return result;
235 }
236
237 /////////////////////////////////////////// ClusterDecay ////////////////////////////////////////////////////////////
238 //
239 //
240
241 G4HadFinalState* G4ANuTauNucleusCcModel::ApplyYourself(
242 const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
243 {
244 theParticleChange.Clear();
245 fProton = f2p2h = fBreak = false;
246 fCascade = fString = false;
247 fLVh = fLVl = fLVt = fLVcpi = G4LorentzVector(0.,0.,0.,0.);
248
249 const G4HadProjectile* aParticle = &aTrack;
250 G4double energy = aParticle->GetTotalEnergy();
251
252 G4String pName = aParticle->GetDefinition()->GetParticleName();
253
254 if( energy < fMinNuEnergy )
255 {
256 theParticleChange.SetEnergyChange(energy);
257 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
258 return &theParticleChange;
259 }
260
261 SampleLVkr( aTrack, targetNucleus);
262
263 if( fBreak == true || fEmu < fMtau ) // ~5*10^-6
264 {
265 // G4cout<<"ni, ";
266 theParticleChange.SetEnergyChange(energy);
267 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
268 return &theParticleChange;
269 }
270
271 // LVs of initial state
272
273 G4LorentzVector lvp1 = aParticle->Get4Momentum();
274 G4LorentzVector lvt1( 0., 0., 0., fM1 );
275 G4double mPip = G4ParticleTable::GetParticleTable()->FindParticle(211)->GetPDGMass();
276
277 // 1-pi by fQtransfer && nu-energy
278 G4LorentzVector lvpip1( 0., 0., 0., mPip );
279 G4LorentzVector lvsum, lv2, lvX;
280 G4ThreeVector eP;
281 G4double cost(1.), sint(0.), phi(0.), muMom(0.), massX2(0.), massX(0.), massR(0.), eCut(0.);
282 G4DynamicParticle* aLept = nullptr; // lepton lv
283
284 G4int Z = targetNucleus.GetZ_asInt();
285 G4int A = targetNucleus.GetA_asInt();
286 G4double mTarg = targetNucleus.AtomicMass(A,Z);
287 G4int pdgP(0), qB(0);
288 // G4double mSum = G4ParticleTable::GetParticleTable()->FindParticle(2212)->GetPDGMass() + mPip;
289
290 G4int iPi = GetOnePionIndex(energy);
291 G4double p1pi = GetNuMuOnePionProb( iPi, energy);
292
293 if( p1pi > G4UniformRand() && fCosTheta > 0.9 ) // && fQtransfer < 0.95*GeV ) // mu- & coherent pion + nucleus
294 {
295 // lvsum = lvp1 + lvpip1;
296 lvsum = lvp1 + lvt1;
297 // cost = fCosThetaPi;
298 cost = fCosTheta;
299 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
300 phi = G4UniformRand()*CLHEP::twopi;
301 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
302
303 // muMom = sqrt(fEmuPi*fEmuPi-fMtau*fMtau);
304 muMom = sqrt(fEmu*fEmu-fMtau*fMtau);
305
306 eP *= muMom;
307
308 // lv2 = G4LorentzVector( eP, fEmuPi );
309 // lv2 = G4LorentzVector( eP, fEmu );
310 lv2 = fLVl;
311
312 // lvX = lvsum - lv2;
313 lvX = fLVh;
314 massX2 = lvX.m2();
315 massX = lvX.m();
316 massR = fLVt.m();
317
318 if ( massX2 <= 0. ) // vmg: very rarely ~ (1-4)e-6 due to big Q2/x, to be improved
319 {
320 fCascade = true;
321 theParticleChange.SetEnergyChange(energy);
322 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
323 return &theParticleChange;
324 }
325 fW2 = massX2;
326
327 if( pName == "anti_nu_tau" ) aLept = new G4DynamicParticle( theTauPlus, lv2 );
328 // else if( pName == "anti_nu_tau") aLept = new G4DynamicParticle( theTauPlus, lv2 );
329 else
330 {
331 theParticleChange.SetEnergyChange(energy);
332 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
333 return &theParticleChange;
334 }
335 if( pName == "anti_nu_tau" ) pdgP = 211;
336 // else pdgP = -211;
337 // eCut = fMpi + 0.5*(fMpi*fMpi-massX2)/mTarg; // massX -> fMpi
338
339 if( A > 1 )
340 {
341 eCut = (fMpi + mTarg)*(fMpi + mTarg) - (massX + massR)*(massX + massR);
342 eCut /= 2.*massR;
343 eCut += massX;
344 }
345 else eCut = fM1 + fMpi;
346
347 if ( lvX.e() > eCut ) // && sqrt( GetW2() ) < 1.4*GeV ) //
348 {
349 CoherentPion( lvX, pdgP, targetNucleus);
350 }
351 else
352 {
353 fCascade = true;
354 theParticleChange.SetEnergyChange(energy);
355 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
356 return &theParticleChange;
357 }
358 theParticleChange.AddSecondary( aLept, fSecID );
359
360 return &theParticleChange;
361 }
362 else // lepton part in lab
363 {
364 lvsum = lvp1 + lvt1;
365 cost = fCosTheta;
366 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
367 phi = G4UniformRand()*CLHEP::twopi;
368 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
369
370 muMom = sqrt(fEmu*fEmu-fMtau*fMtau);
371
372 eP *= muMom;
373
374 lv2 = G4LorentzVector( eP, fEmu );
375 lv2 = fLVl;
376 lvX = lvsum - lv2;
377 lvX = fLVh;
378 massX2 = lvX.m2();
379
380 if ( massX2 <= 0. ) // vmg: very rarely ~ (1-4)e-6 due to big Q2/x, to be improved
381 {
382 fCascade = true;
383 theParticleChange.SetEnergyChange(energy);
384 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
385 return &theParticleChange;
386 }
387 fW2 = massX2;
388
389 if( pName == "anti_nu_tau" ) aLept = new G4DynamicParticle( theTauPlus, lv2 );
390 // else if( pName == "anti_nu_tau") aLept = new G4DynamicParticle( theTauPlus, lv2 );
391 else
392 {
393 theParticleChange.SetEnergyChange(energy);
394 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
395 return &theParticleChange;
396 }
397 theParticleChange.AddSecondary( aLept, fSecID );
398 }
399
400 // hadron part
401
402 fRecoil = nullptr;
403
404 if( A == 1 )
405 {
406 if( pName == "anti_nu_tau" ) qB = 2;
407 // else qB = 0;
408
409 // if( G4UniformRand() > 0.1 ) // > 0.9999 ) // > 0.0001 ) //
410 {
411 ClusterDecay( lvX, qB );
412 }
413 return &theParticleChange;
414 }
415 /*
416 // else
417 {
418 if( pName == "anti_nu_tau" ) pdgP = 211;
419 else pdgP = -211;
420
421
422 if ( fQtransfer < 0.95*GeV ) // < 0.35*GeV ) //
423 {
424 if( lvX.m() > mSum ) CoherentPion( lvX, pdgP, targetNucleus);
425 }
426 }
427 return &theParticleChange;
428 }
429 */
430 G4Nucleus recoil;
431 G4double rM(0.), ratio = G4double(Z)/G4double(A);
432
433 if( ratio > G4UniformRand() ) // proton is excited
434 {
435 fProton = true;
436 recoil = G4Nucleus(A-1,Z-1);
437 fRecoil = &recoil;
438 rM = recoil.AtomicMass(A-1,Z-1);
439
440 if( pName == "anti_nu_tau" ) // (++) state -> p + pi+
441 {
442 fMt = G4ParticleTable::GetParticleTable()->FindParticle(2212)->GetPDGMass()
443 + G4ParticleTable::GetParticleTable()->FindParticle(211)->GetPDGMass();
444 }
445 else // (0) state -> p + pi-, n + pi0
446 {
447 // fMt = G4ParticleTable::GetParticleTable()->FindParticle(2212)->GetPDGMass()
448 // + G4ParticleTable::GetParticleTable()->FindParticle(-211)->GetPDGMass();
449 }
450 }
451 else // excited neutron
452 {
453 fProton = false;
454 recoil = G4Nucleus(A-1,Z);
455 fRecoil = &recoil;
456 rM = recoil.AtomicMass(A-1,Z);
457
458 if( pName == "anti_nu_tau" ) // (+) state -> n + pi+
459 {
460 fMt = G4ParticleTable::GetParticleTable()->FindParticle(2112)->GetPDGMass()
461 + G4ParticleTable::GetParticleTable()->FindParticle(211)->GetPDGMass();
462 }
463 else // (-) state -> n + pi-, // n + pi0
464 {
465 // fMt = G4ParticleTable::GetParticleTable()->FindParticle(2112)->GetPDGMass()
466 // + G4ParticleTable::GetParticleTable()->FindParticle(-211)->GetPDGMass();
467 }
468 }
469 // G4int index = GetEnergyIndex(energy);
470 G4int nepdg = aParticle->GetDefinition()->GetPDGEncoding();
471
472 G4double qeTotRat; // = GetNuMuQeTotRat(index, energy);
473 qeTotRat = CalculateQEratioA( Z, A, energy, nepdg);
474
475 G4ThreeVector dX = (lvX.vect()).unit();
476 G4double eX = lvX.e(); // excited nucleon
477 G4double mX = sqrt(massX2);
478 // G4double pX = sqrt( eX*eX - mX*mX );
479 // G4double sumE = eX + rM;
480
481 if( qeTotRat > G4UniformRand() || mX <= fMt ) // || eX <= 1232.*MeV) // QE
482 {
483 fString = false;
484
485 if( fProton )
486 {
487 fPDGencoding = 2212;
488 fMr = proton_mass_c2;
489 recoil = G4Nucleus(A-1,Z-1);
490 fRecoil = &recoil;
491 rM = recoil.AtomicMass(A-1,Z-1);
492 }
493 else // if( pName == "anti_nu_tau" )
494 {
495 fPDGencoding = 2112;
496 fMr = G4ParticleTable::GetParticleTable()->
497 FindParticle(fPDGencoding)->GetPDGMass(); // 939.5654133*MeV;
498 recoil = G4Nucleus(A-1,Z);
499 fRecoil = &recoil;
500 rM = recoil.AtomicMass(A-1,Z);
501 }
502 // sumE = eX + rM;
503 G4double eTh = fMr + 0.5*(fMr*fMr - mX*mX)/rM;
504
505 if( eX <= eTh ) // vmg, very rarely out of kinematics
506 {
507 fString = true;
508 theParticleChange.SetEnergyChange(energy);
509 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
510 return &theParticleChange;
511 }
512 // FinalBarion( fLVh, 0, fPDGencoding ); // p(n)+deexcited recoil
513 FinalBarion( lvX, 0, fPDGencoding ); // p(n)+deexcited recoil
514 }
515 else // if ( eX < 9500000.*GeV ) // < 25.*GeV) // < 95.*GeV ) // < 2.5*GeV ) //cluster decay
516 {
517 if ( fProton && pName == "anti_nu_tau" ) qB = 2;
518 // else if( fProton && pName == "anti_nu_tau" ) qB = 0;
519 else if( !fProton && pName == "anti_nu_tau" ) qB = 1;
520 // else if( !fProton && pName == "anti_nu_tau" ) qB = -1;
521
522
523 ClusterDecay( lvX, qB );
524 }
525 return &theParticleChange;
526 }
527
528
529 /////////////////////////////////////////////////////////////////////
530 ////////////////////////////////////////////////////////////////////
531 ///////////////////////////////////////////////////////////////////
532
533 /////////////////////////////////////////////////
534 //
535 // sample x, then Q2
536
537 void G4ANuTauNucleusCcModel::SampleLVkr(const G4HadProjectile & aTrack, G4Nucleus& targetNucleus)
538 {
539 fBreak = false;
540 G4int A = targetNucleus.GetA_asInt(), iTer(0), iTerMax(100);
541 G4int Z = targetNucleus.GetZ_asInt();
542 G4double e3(0.), pMu2(0.), pX2(0.), nMom(0.), rM(0.), hM(0.), tM = targetNucleus.AtomicMass(A,Z);
543 G4double Ex(0.), ei(0.), nm2(0.);
544 G4double cost(1.), sint(0.), phi(0.), muMom(0.);
545 G4ThreeVector eP, bst;
546 const G4HadProjectile* aParticle = &aTrack;
547 G4LorentzVector lvp1 = aParticle->Get4Momentum();
548
549 if( A == 1 ) // hydrogen, no Fermi motion ???
550 {
551 fNuEnergy = aParticle->GetTotalEnergy();
552 iTer = 0;
553
554 do
555 {
556 fXsample = SampleXkr(fNuEnergy);
557 fQtransfer = SampleQkr(fNuEnergy, fXsample);
558 fQ2 = fQtransfer*fQtransfer;
559
560 if( fXsample > 0. )
561 {
562 fW2 = fM1*fM1 - fQ2 + fQ2/fXsample; // sample excited hadron mass
563 fEmu = fNuEnergy - fQ2/2./fM1/fXsample;
564 }
565 else
566 {
567 fW2 = fM1*fM1;
568 fEmu = fNuEnergy;
569 }
570 e3 = fNuEnergy + fM1 - fEmu;
571
572 if( e3 < sqrt(fW2) ) G4cout<<"energyX = "<<e3/GeV<<", fW = "<<sqrt(fW2)/GeV<<G4endl;
573
574 pMu2 = fEmu*fEmu - fMtau*fMtau;
575
576 if(pMu2 < 0.) { fBreak = true; return; }
577
578 pX2 = e3*e3 - fW2;
579
580 fCosTheta = fNuEnergy*fNuEnergy + pMu2 - pX2;
581 fCosTheta /= 2.*fNuEnergy*sqrt(pMu2);
582 iTer++;
583 }
584 while( ( abs(fCosTheta) > 1. || fEmu < fMtau ) && iTer < iTerMax );
585
586 if( iTer >= iTerMax ) { fBreak = true; return; }
587
588 if( abs(fCosTheta) > 1.) // vmg: due to big Q2/x values. To be improved ...
589 {
590 G4cout<<"H2: fCosTheta = "<<fCosTheta<<", fEmu = "<<fEmu<<G4endl;
591 // fCosTheta = -1. + 2.*G4UniformRand();
592 if(fCosTheta < -1.) fCosTheta = -1.;
593 if(fCosTheta > 1.) fCosTheta = 1.;
594 }
595 // LVs
596
597 G4LorentzVector lvt1 = G4LorentzVector( 0., 0., 0., fM1 );
598 G4LorentzVector lvsum = lvp1 + lvt1;
599
600 cost = fCosTheta;
601 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
602 phi = G4UniformRand()*CLHEP::twopi;
603 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
604 muMom = sqrt(fEmu*fEmu-fMtau*fMtau);
605 eP *= muMom;
606 fLVl = G4LorentzVector( eP, fEmu );
607
608 fLVh = lvsum - fLVl;
609 fLVt = G4LorentzVector( 0., 0., 0., 0. ); // no recoil
610 }
611 else // Fermi motion, Q2 in nucleon rest frame
612 {
613 G4Nucleus recoil1( A-1, Z );
614 rM = recoil1.AtomicMass(A-1,Z);
615 do
616 {
617 // nMom = NucleonMomentumBR( targetNucleus ); // BR
618 nMom = GgSampleNM( targetNucleus ); // Gg
619 Ex = GetEx(A-1, fProton);
620 ei = tM - sqrt( (rM + Ex)*(rM + Ex) + nMom*nMom );
621 // ei = 0.5*( tM - s2M - 2*eX );
622
623 nm2 = ei*ei - nMom*nMom;
624 iTer++;
625 }
626 while( nm2 < 0. && iTer < iTerMax );
627
628 if( iTer >= iTerMax ) { fBreak = true; return; }
629
630 G4ThreeVector nMomDir = nMom*G4RandomDirection();
631
632 if( !f2p2h || A < 3 ) // 1p1h
633 {
634 // hM = tM - rM;
635
636 fLVt = G4LorentzVector( -nMomDir, sqrt( (rM + Ex)*(rM + Ex) + nMom*nMom ) ); // rM ); //
637 fLVh = G4LorentzVector( nMomDir, ei ); // hM); //
638 }
639 else // 2p2h
640 {
641 G4Nucleus recoil(A-2,Z-1);
642 rM = recoil.AtomicMass(A-2,Z-1)+sqrt(nMom*nMom+fM1*fM1);
643 hM = tM - rM;
644
645 fLVt = G4LorentzVector( nMomDir, sqrt( rM*rM+nMom*nMom ) );
646 fLVh = G4LorentzVector(-nMomDir, sqrt( hM*hM+nMom*nMom ) );
647 }
648 // G4cout<<hM<<", ";
649 // bst = fLVh.boostVector();
650
651 // lvp1.boost(-bst); // -> nucleon rest system, where Q2 transfer is ???
652
653 fNuEnergy = lvp1.e();
654 // G4double mN = fLVh.m(); // better mN = fM1 !? vmg
655 iTer = 0;
656
657 do // no FM!?, 5.4.20 vmg
658 {
659 fXsample = SampleXkr(fNuEnergy);
660 fQtransfer = SampleQkr(fNuEnergy, fXsample);
661 fQ2 = fQtransfer*fQtransfer;
662
663 // G4double mR = mN + fM1*(A-1.)*std::exp(-2.0*fQtransfer/mN); // recoil mass in+el
664
665 if( fXsample > 0. )
666 {
667 fW2 = fM1*fM1 - fQ2 + fQ2/fXsample; // sample excited hadron mass
668
669 // fW2 = mN*mN - fQ2 + fQ2/fXsample; // sample excited hadron mass
670 // fEmu = fNuEnergy - fQ2/2./mR/fXsample; // fM1->mN
671
672 fEmu = fNuEnergy - fQ2/2./fM1/fXsample; // fM1->mN
673 }
674 else
675 {
676 // fW2 = mN*mN;
677
678 fW2 = fM1*fM1;
679 fEmu = fNuEnergy;
680 }
681 // if(fEmu < 0.) G4cout<<"fEmu = "<<fEmu<<" hM = "<<hM<<G4endl;
682 // e3 = fNuEnergy + mR - fEmu;
683
684 e3 = fNuEnergy + fM1 - fEmu;
685
686 // if( e3 < sqrt(fW2) ) G4cout<<"energyX = "<<e3/GeV<<", fW = "<<sqrt(fW2)/GeV<<G4endl;
687
688 pMu2 = fEmu*fEmu - fMtau*fMtau;
689 pX2 = e3*e3 - fW2;
690
691 if(pMu2 < 0.) { fBreak = true; return; }
692
693 fCosTheta = fNuEnergy*fNuEnergy + pMu2 - pX2;
694 fCosTheta /= 2.*fNuEnergy*sqrt(pMu2);
695 iTer++;
696 }
697 while( ( abs(fCosTheta) > 1. || fEmu < fMtau ) && iTer < iTerMax );
698
699 if( iTer >= iTerMax ) { fBreak = true; return; }
700
701 if( abs(fCosTheta) > 1.) // vmg: due to big Q2/x values. To be improved ...
702 {
703 G4cout<<"FM: fCosTheta = "<<fCosTheta<<", fEmu = "<<fEmu<<G4endl;
704 // fCosTheta = -1. + 2.*G4UniformRand();
705 if( fCosTheta < -1.) fCosTheta = -1.;
706 if( fCosTheta > 1.) fCosTheta = 1.;
707 }
708 // LVs
709 // G4LorentzVector lvt1 = G4LorentzVector( 0., 0., 0., mN ); // fM1 );
710
711 G4LorentzVector lvt1 = G4LorentzVector( 0., 0., 0., fM1 ); // fM1 );
712 G4LorentzVector lvsum = lvp1 + lvt1;
713
714 cost = fCosTheta;
715 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
716 phi = G4UniformRand()*CLHEP::twopi;
717 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
718 muMom = sqrt(fEmu*fEmu-fMtau*fMtau);
719 eP *= muMom;
720 fLVl = G4LorentzVector( eP, fEmu );
721 fLVh = lvsum - fLVl;
722
723 // if( fLVh.e() < mN || fLVh.m2() < 0.) { fBreak = true; return; }
724
725 if( fLVh.e() < fM1 || fLVh.m2() < 0.) { fBreak = true; return; }
726
727 // back to lab system
728
729 // fLVl.boost(bst);
730 // fLVh.boost(bst);
731 }
732 //G4cout<<iTer<<", "<<fBreak<<"; ";
733 }
734
735 //
736 //
737 ///////////////////////////
738