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26 // $Id: G4NuMuNucleusCcModel.cc 91806 2015-08-06 12:20:45Z gcosmo $
27 //
28 // Geant4 Header : G4NuMuNucleusCcModel
29 //
30 // Author : V.Grichine 12.2.19
31 //
32
33 #include <iostream>
34 #include <fstream>
35 #include <sstream>
36
37 #include "G4NuMuNucleusCcModel.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 "G4MuonMinus.hh"
82 #include "G4MuonPlus.hh"
83 #include "G4Nucleus.hh"
84 #include "G4LorentzVector.hh"
85
86 using namespace std;
87 using namespace CLHEP;
88
89 #ifdef G4MULTITHREADED
90 G4Mutex G4NuMuNucleusCcModel::numuNucleusModel = G4MUTEX_INITIALIZER;
91 #endif
92
93
94 G4NuMuNucleusCcModel::G4NuMuNucleusCcModel(const G4String& name)
95 : G4NeutrinoNucleusModel(name)
96 {
97 fData = fMaster = false;
98 InitialiseModel();
99 }
100
101
102 G4NuMuNucleusCcModel::~G4NuMuNucleusCcModel()
103 {}
104
105
106 void G4NuMuNucleusCcModel::ModelDescription(std::ostream& outFile) const
107 {
108
109 outFile << "G4NuMuNucleusCcModel is a neutrino-nucleus (charge current) scattering\n"
110 << "model which uses the standard model \n"
111 << "transfer parameterization. The model is fully relativistic\n";
112
113 }
114
115 /////////////////////////////////////////////////////////
116 //
117 // Read data from G4PARTICLEXSDATA (locally PARTICLEXSDATA)
118
119 void G4NuMuNucleusCcModel::InitialiseModel()
120 {
121 G4String pName = "nu_mu";
122 // G4String pName = "anti_nu_mu";
123
124 G4int nSize(0), i(0), j(0), k(0);
125
126 if(!fData)
127 {
128 #ifdef G4MULTITHREADED
129 G4MUTEXLOCK(&numuNucleusModel);
130 if(!fData)
131 {
132 #endif
133 fMaster = true;
134 #ifdef G4MULTITHREADED
135 }
136 G4MUTEXUNLOCK(&numuNucleusModel);
137 #endif
138 }
139
140 if(fMaster)
141 {
142 const char* path = G4FindDataDir("G4PARTICLEXSDATA");
143 std::ostringstream ost1, ost2, ost3, ost4;
144 ost1 << path << "/" << "neutrino" << "/" << pName << "/xarraycckr";
145
146 std::ifstream filein1( ost1.str().c_str() );
147
148 // filein.open("$PARTICLEXSDATA/");
149
150 filein1>>nSize;
151
152 for( k = 0; k < fNbin; ++k )
153 {
154 for( i = 0; i <= fNbin; ++i )
155 {
156 filein1 >> fNuMuXarrayKR[k][i];
157 // G4cout<< fNuMuXarrayKR[k][i] << " ";
158 }
159 }
160 // G4cout<<G4endl<<G4endl;
161
162 ost2 << path << "/" << "neutrino" << "/" << pName << "/xdistrcckr";
163 std::ifstream filein2( ost2.str().c_str() );
164
165 filein2>>nSize;
166
167 for( k = 0; k < fNbin; ++k )
168 {
169 for( i = 0; i < fNbin; ++i )
170 {
171 filein2 >> fNuMuXdistrKR[k][i];
172 // G4cout<< fNuMuXdistrKR[k][i] << " ";
173 }
174 }
175 // G4cout<<G4endl<<G4endl;
176
177 ost3 << path << "/" << "neutrino" << "/" << pName << "/q2arraycckr";
178 std::ifstream filein3( ost3.str().c_str() );
179
180 filein3>>nSize;
181
182 for( k = 0; k < fNbin; ++k )
183 {
184 for( i = 0; i <= fNbin; ++i )
185 {
186 for( j = 0; j <= fNbin; ++j )
187 {
188 filein3 >> fNuMuQarrayKR[k][i][j];
189 // G4cout<< fNuMuQarrayKR[k][i][j] << " ";
190 }
191 }
192 }
193 // G4cout<<G4endl<<G4endl;
194
195 ost4 << path << "/" << "neutrino" << "/" << pName << "/q2distrcckr";
196 std::ifstream filein4( ost4.str().c_str() );
197
198 filein4>>nSize;
199
200 for( k = 0; k < fNbin; ++k )
201 {
202 for( i = 0; i <= fNbin; ++i )
203 {
204 for( j = 0; j < fNbin; ++j )
205 {
206 filein4 >> fNuMuQdistrKR[k][i][j];
207 // G4cout<< fNuMuQdistrKR[k][i][j] << " ";
208 }
209 }
210 }
211 fData = true;
212 }
213 }
214
215 /////////////////////////////////////////////////////////
216
217 G4bool G4NuMuNucleusCcModel::IsApplicable(const G4HadProjectile & aPart,
218 G4Nucleus & )
219 {
220 G4bool result = false;
221 G4String pName = aPart.GetDefinition()->GetParticleName();
222 G4double energy = aPart.GetTotalEnergy();
223
224 if( pName == "nu_mu" // || pName == "anti_nu_mu" )
225 &&
226 energy > fMinNuEnergy )
227 {
228 result = true;
229 }
230
231 return result;
232 }
233
234 /////////////////////////////////////////// ClusterDecay ////////////////////////////////////////////////////////////
235 //
236 //
237
238 G4HadFinalState* G4NuMuNucleusCcModel::ApplyYourself(
239 const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
240 {
241 theParticleChange.Clear();
242 fProton = f2p2h = fBreak = false;
243 fCascade = fString = false;
244 fLVh = fLVl = fLVt = fLVcpi = G4LorentzVector(0.,0.,0.,0.);
245
246 const G4HadProjectile* aParticle = &aTrack;
247 G4double energy = aParticle->GetTotalEnergy();
248
249 G4String pName = aParticle->GetDefinition()->GetParticleName();
250
251 if( energy < fMinNuEnergy )
252 {
253 theParticleChange.SetEnergyChange(energy);
254 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
255 return &theParticleChange;
256 }
257
258 SampleLVkr( aTrack, targetNucleus);
259
260 if( fBreak == true || fEmu < fMu ) // ~5*10^-6
261 {
262 // G4cout<<"ni, ";
263 theParticleChange.SetEnergyChange(energy);
264 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
265 return &theParticleChange;
266 }
267
268 // LVs of initial state
269
270 G4LorentzVector lvp1 = aParticle->Get4Momentum();
271 G4LorentzVector lvt1( 0., 0., 0., fM1 );
272 G4double mPip = G4ParticleTable::GetParticleTable()->FindParticle(211)->GetPDGMass();
273
274 // 1-pi by fQtransfer && nu-energy
275 G4LorentzVector lvpip1( 0., 0., 0., mPip );
276 G4LorentzVector lvsum, lv2, lvX;
277 G4ThreeVector eP;
278 G4double cost(1.), sint(0.), phi(0.), muMom(0.), massX2(0.), massX(0.), massR(0.), eCut(0.);
279 G4DynamicParticle* aLept = nullptr; // lepton lv
280
281 G4int Z = targetNucleus.GetZ_asInt();
282 G4int A = targetNucleus.GetA_asInt();
283 G4double mTarg = targetNucleus.AtomicMass(A,Z);
284 G4int pdgP(0), qB(0);
285 // G4double mSum = G4ParticleTable::GetParticleTable()->FindParticle(2212)->GetPDGMass() + mPip;
286
287 G4int iPi = GetOnePionIndex(energy);
288 G4double p1pi = GetNuMuOnePionProb( iPi, energy);
289
290 if( p1pi > G4UniformRand() && fCosTheta > 0.9 ) // && fQtransfer < 0.95*GeV ) // mu- & coherent pion + nucleus
291 {
292 // lvsum = lvp1 + lvpip1;
293 lvsum = lvp1 + lvt1;
294 // cost = fCosThetaPi;
295 cost = fCosTheta;
296 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
297 phi = G4UniformRand()*CLHEP::twopi;
298 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
299
300 // muMom = sqrt(fEmuPi*fEmuPi-fMu*fMu);
301 muMom = sqrt(fEmu*fEmu-fMu*fMu);
302
303 eP *= muMom;
304
305 // lv2 = G4LorentzVector( eP, fEmuPi );
306 // lv2 = G4LorentzVector( eP, fEmu );
307 lv2 = fLVl;
308
309 // lvX = lvsum - lv2;
310 lvX = fLVh;
311 massX2 = lvX.m2();
312 massX = lvX.m();
313 massR = fLVt.m();
314
315 if ( massX2 <= 0. ) // vmg: very rarely ~ (1-4)e-6 due to big Q2/x, to be improved
316 {
317 fCascade = true;
318 theParticleChange.SetEnergyChange(energy);
319 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
320 return &theParticleChange;
321 }
322 fW2 = massX2;
323
324 if( pName == "nu_mu" ) aLept = new G4DynamicParticle( theMuonMinus, lv2 );
325 // else if( pName == "anti_nu_mu") aLept = new G4DynamicParticle( theMuonPlus, lv2 );
326 else
327 {
328 theParticleChange.SetEnergyChange(energy);
329 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
330 return &theParticleChange;
331 }
332 if( pName == "nu_mu" ) pdgP = 211;
333 // else pdgP = -211;
334 // eCut = fMpi + 0.5*(fMpi*fMpi-massX2)/mTarg; // massX -> fMpi
335
336 if( A > 1 )
337 {
338 eCut = (fMpi + mTarg)*(fMpi + mTarg) - (massX + massR)*(massX + massR);
339 eCut /= 2.*massR;
340 eCut += massX;
341 }
342 else eCut = fM1 + fMpi;
343
344 if ( lvX.e() > eCut ) // && sqrt( GetW2() ) < 1.4*GeV ) //
345 {
346 CoherentPion( lvX, pdgP, targetNucleus);
347 }
348 else
349 {
350 fCascade = true;
351 theParticleChange.SetEnergyChange(energy);
352 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
353 return &theParticleChange;
354 }
355 theParticleChange.AddSecondary( aLept, fSecID );
356
357 return &theParticleChange;
358 }
359 else // lepton part in lab
360 {
361 lvsum = lvp1 + lvt1;
362 cost = fCosTheta;
363 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
364 phi = G4UniformRand()*CLHEP::twopi;
365 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
366
367 muMom = sqrt(fEmu*fEmu-fMu*fMu);
368
369 eP *= muMom;
370
371 lv2 = G4LorentzVector( eP, fEmu );
372 lv2 = fLVl;
373 lvX = lvsum - lv2;
374 lvX = fLVh;
375 massX2 = lvX.m2();
376
377 if ( massX2 <= 0. ) // vmg: very rarely ~ (1-4)e-6 due to big Q2/x, to be improved
378 {
379 fCascade = true;
380 theParticleChange.SetEnergyChange(energy);
381 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
382 return &theParticleChange;
383 }
384 fW2 = massX2;
385
386 if( pName == "nu_mu" ) aLept = new G4DynamicParticle( theMuonMinus, lv2 );
387 // else if( pName == "anti_nu_mu") aLept = new G4DynamicParticle( theMuonPlus, lv2 );
388 else
389 {
390 theParticleChange.SetEnergyChange(energy);
391 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
392 return &theParticleChange;
393 }
394 theParticleChange.AddSecondary( aLept, fSecID );
395 }
396
397 // hadron part
398
399 fRecoil = nullptr;
400
401 if( A == 1 )
402 {
403 if( pName == "nu_mu" ) qB = 2;
404 // else qB = 0;
405
406 // if( G4UniformRand() > 0.1 ) // > 0.9999 ) // > 0.0001 ) //
407 {
408 ClusterDecay( lvX, qB );
409 }
410 return &theParticleChange;
411 }
412 /*
413 // else
414 {
415 if( pName == "nu_mu" ) pdgP = 211;
416 else pdgP = -211;
417
418
419 if ( fQtransfer < 0.95*GeV ) // < 0.35*GeV ) //
420 {
421 if( lvX.m() > mSum ) CoherentPion( lvX, pdgP, targetNucleus);
422 }
423 }
424 return &theParticleChange;
425 }
426 */
427 G4Nucleus recoil;
428 G4double rM(0.), ratio = G4double(Z)/G4double(A);
429
430 if( ratio > G4UniformRand() ) // proton is excited
431 {
432 fProton = true;
433 recoil = G4Nucleus(A-1,Z-1);
434 fRecoil = &recoil;
435 rM = recoil.AtomicMass(A-1,Z-1);
436
437 if( pName == "nu_mu" ) // (++) state -> p + pi+
438 {
439 fMt = G4ParticleTable::GetParticleTable()->FindParticle(2212)->GetPDGMass()
440 + G4ParticleTable::GetParticleTable()->FindParticle(211)->GetPDGMass();
441 }
442 else // (0) state -> p + pi-, n + pi0
443 {
444 // fMt = G4ParticleTable::GetParticleTable()->FindParticle(2212)->GetPDGMass()
445 // + G4ParticleTable::GetParticleTable()->FindParticle(-211)->GetPDGMass();
446 }
447 }
448 else // excited neutron
449 {
450 fProton = false;
451 recoil = G4Nucleus(A-1,Z);
452 fRecoil = &recoil;
453 rM = recoil.AtomicMass(A-1,Z);
454
455 if( pName == "nu_mu" ) // (+) state -> n + pi+
456 {
457 fMt = G4ParticleTable::GetParticleTable()->FindParticle(2112)->GetPDGMass()
458 + G4ParticleTable::GetParticleTable()->FindParticle(211)->GetPDGMass();
459 }
460 else // (-) state -> n + pi-, // n + pi0
461 {
462 // fMt = G4ParticleTable::GetParticleTable()->FindParticle(2112)->GetPDGMass()
463 // + G4ParticleTable::GetParticleTable()->FindParticle(-211)->GetPDGMass();
464 }
465 }
466 // G4int index = GetEnergyIndex(energy);
467 G4int nepdg = aParticle->GetDefinition()->GetPDGEncoding();
468
469 G4double qeTotRat; // = GetNuMuQeTotRat(index, energy);
470 qeTotRat = CalculateQEratioA( Z, A, energy, nepdg);
471
472 G4ThreeVector dX = (lvX.vect()).unit();
473 G4double eX = lvX.e(); // excited nucleon
474 G4double mX = sqrt(massX2);
475 // G4double pX = sqrt( eX*eX - mX*mX );
476 // G4double sumE = eX + rM;
477
478 if( qeTotRat > G4UniformRand() || mX <= fMt ) // || eX <= 1232.*MeV) // QE
479 {
480 fString = false;
481
482 if( fProton )
483 {
484 fPDGencoding = 2212;
485 fMr = proton_mass_c2;
486 recoil = G4Nucleus(A-1,Z-1);
487 fRecoil = &recoil;
488 rM = recoil.AtomicMass(A-1,Z-1);
489 }
490 else // if( pName == "anti_nu_mu" )
491 {
492 fPDGencoding = 2112;
493 fMr = G4ParticleTable::GetParticleTable()->
494 FindParticle(fPDGencoding)->GetPDGMass(); // 939.5654133*MeV;
495 recoil = G4Nucleus(A-1,Z);
496 fRecoil = &recoil;
497 rM = recoil.AtomicMass(A-1,Z);
498 }
499 // sumE = eX + rM;
500 G4double eTh = fMr + 0.5*(fMr*fMr - mX*mX)/rM;
501
502 if( eX <= eTh ) // vmg, very rarely out of kinematics
503 {
504 fString = true;
505 theParticleChange.SetEnergyChange(energy);
506 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
507 return &theParticleChange;
508 }
509 // FinalBarion( fLVh, 0, fPDGencoding ); // p(n)+deexcited recoil
510 FinalBarion( lvX, 0, fPDGencoding ); // p(n)+deexcited recoil
511 }
512 else // if ( eX < 9500000.*GeV ) // < 25.*GeV) // < 95.*GeV ) // < 2.5*GeV ) //cluster decay
513 {
514 if ( fProton && pName == "nu_mu" ) qB = 2;
515 // else if( fProton && pName == "anti_nu_mu" ) qB = 0;
516 else if( !fProton && pName == "nu_mu" ) qB = 1;
517 // else if( !fProton && pName == "anti_nu_mu" ) qB = -1;
518
519
520 ClusterDecay( lvX, qB );
521 }
522 return &theParticleChange;
523 }
524
525
526 /////////////////////////////////////////////////////////////////////
527 ////////////////////////////////////////////////////////////////////
528 ///////////////////////////////////////////////////////////////////
529
530 /////////////////////////////////////////////////
531 //
532 // sample x, then Q2
533
534 void G4NuMuNucleusCcModel::SampleLVkr(const G4HadProjectile & aTrack, G4Nucleus& targetNucleus)
535 {
536 fBreak = false;
537 G4int A = targetNucleus.GetA_asInt(), iTer(0), iTerMax(100);
538 G4int Z = targetNucleus.GetZ_asInt();
539 G4double e3(0.), pMu2(0.), pX2(0.), nMom(0.), rM(0.), hM(0.), tM = targetNucleus.AtomicMass(A,Z);
540 G4double Ex(0.), ei(0.), nm2(0.);
541 G4double cost(1.), sint(0.), phi(0.), muMom(0.);
542 G4ThreeVector eP, bst;
543 const G4HadProjectile* aParticle = &aTrack;
544 G4LorentzVector lvp1 = aParticle->Get4Momentum();
545
546 if( A == 1 ) // hydrogen, no Fermi motion ???
547 {
548 fNuEnergy = aParticle->GetTotalEnergy();
549 iTer = 0;
550
551 do
552 {
553 fXsample = SampleXkr(fNuEnergy);
554 fQtransfer = SampleQkr(fNuEnergy, fXsample);
555 fQ2 = fQtransfer*fQtransfer;
556
557 if( fXsample > 0. )
558 {
559 fW2 = fM1*fM1 - fQ2 + fQ2/fXsample; // sample excited hadron mass
560 fEmu = fNuEnergy - fQ2/2./fM1/fXsample;
561 }
562 else
563 {
564 fW2 = fM1*fM1;
565 fEmu = fNuEnergy;
566 }
567 e3 = fNuEnergy + fM1 - fEmu;
568
569 if( e3 < sqrt(fW2) ) G4cout<<"energyX = "<<e3/GeV<<", fW = "<<sqrt(fW2)/GeV<<G4endl;
570
571 pMu2 = fEmu*fEmu - fMu*fMu;
572
573 if(pMu2 < 0.) { fBreak = true; return; }
574
575 pX2 = e3*e3 - fW2;
576
577 fCosTheta = fNuEnergy*fNuEnergy + pMu2 - pX2;
578 fCosTheta /= 2.*fNuEnergy*sqrt(pMu2);
579 iTer++;
580 }
581 while( ( abs(fCosTheta) > 1. || fEmu < fMu ) && iTer < iTerMax );
582
583 if( iTer >= iTerMax ) { fBreak = true; return; }
584
585 if( abs(fCosTheta) > 1.) // vmg: due to big Q2/x values. To be improved ...
586 {
587 G4cout<<"H2: fCosTheta = "<<fCosTheta<<", fEmu = "<<fEmu<<G4endl;
588 // fCosTheta = -1. + 2.*G4UniformRand();
589 if(fCosTheta < -1.) fCosTheta = -1.;
590 if(fCosTheta > 1.) fCosTheta = 1.;
591 }
592 // LVs
593
594 G4LorentzVector lvt1 = G4LorentzVector( 0., 0., 0., fM1 );
595 G4LorentzVector lvsum = lvp1 + lvt1;
596
597 cost = fCosTheta;
598 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
599 phi = G4UniformRand()*CLHEP::twopi;
600 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
601 muMom = sqrt(fEmu*fEmu-fMu*fMu);
602 eP *= muMom;
603 fLVl = G4LorentzVector( eP, fEmu );
604
605 fLVh = lvsum - fLVl;
606 fLVt = G4LorentzVector( 0., 0., 0., 0. ); // no recoil
607 }
608 else // Fermi motion, Q2 in nucleon rest frame
609 {
610 G4Nucleus recoil1( A-1, Z );
611 rM = recoil1.AtomicMass(A-1,Z);
612 do
613 {
614 // nMom = NucleonMomentumBR( targetNucleus ); // BR
615 nMom = GgSampleNM( targetNucleus ); // Gg
616 Ex = GetEx(A-1, fProton);
617 ei = tM - sqrt( (rM + Ex)*(rM + Ex) + nMom*nMom );
618 // ei = 0.5*( tM - s2M - 2*eX );
619
620 nm2 = ei*ei - nMom*nMom;
621 iTer++;
622 }
623 while( nm2 < 0. && iTer < iTerMax );
624
625 if( iTer >= iTerMax ) { fBreak = true; return; }
626
627 G4ThreeVector nMomDir = nMom*G4RandomDirection();
628
629 if( !f2p2h || A < 3 ) // 1p1h
630 {
631 // hM = tM - rM;
632
633 fLVt = G4LorentzVector( -nMomDir, sqrt( (rM + Ex)*(rM + Ex) + nMom*nMom ) ); // rM ); //
634 fLVh = G4LorentzVector( nMomDir, ei ); // hM); //
635 }
636 else // 2p2h
637 {
638 G4Nucleus recoil(A-2,Z-1);
639 rM = recoil.AtomicMass(A-2,Z-1)+sqrt(nMom*nMom+fM1*fM1);
640 hM = tM - rM;
641
642 fLVt = G4LorentzVector( nMomDir, sqrt( rM*rM+nMom*nMom ) );
643 fLVh = G4LorentzVector(-nMomDir, sqrt( hM*hM+nMom*nMom ) );
644 }
645 // G4cout<<hM<<", ";
646 // bst = fLVh.boostVector();
647
648 // lvp1.boost(-bst); // -> nucleon rest system, where Q2 transfer is ???
649
650 fNuEnergy = lvp1.e();
651 // G4double mN = fLVh.m(); // better mN = fM1 !? vmg
652 iTer = 0;
653
654 do // no FM!?, 5.4.20 vmg
655 {
656 fXsample = SampleXkr(fNuEnergy);
657 fQtransfer = SampleQkr(fNuEnergy, fXsample);
658 fQ2 = fQtransfer*fQtransfer;
659
660 // G4double mR = mN + fM1*(A-1.)*std::exp(-2.0*fQtransfer/mN); // recoil mass in+el
661
662 if( fXsample > 0. )
663 {
664 fW2 = fM1*fM1 - fQ2 + fQ2/fXsample; // sample excited hadron mass
665
666 // fW2 = mN*mN - fQ2 + fQ2/fXsample; // sample excited hadron mass
667 // fEmu = fNuEnergy - fQ2/2./mR/fXsample; // fM1->mN
668
669 fEmu = fNuEnergy - fQ2/2./fM1/fXsample; // fM1->mN
670 }
671 else
672 {
673 // fW2 = mN*mN;
674
675 fW2 = fM1*fM1;
676 fEmu = fNuEnergy;
677 }
678 // if(fEmu < 0.) G4cout<<"fEmu = "<<fEmu<<" hM = "<<hM<<G4endl;
679 // e3 = fNuEnergy + mR - fEmu;
680
681 e3 = fNuEnergy + fM1 - fEmu;
682
683 // if( e3 < sqrt(fW2) ) G4cout<<"energyX = "<<e3/GeV<<", fW = "<<sqrt(fW2)/GeV<<G4endl;
684
685 pMu2 = fEmu*fEmu - fMu*fMu;
686 pX2 = e3*e3 - fW2;
687
688 if(pMu2 < 0.) { fBreak = true; return; }
689
690 fCosTheta = fNuEnergy*fNuEnergy + pMu2 - pX2;
691 fCosTheta /= 2.*fNuEnergy*sqrt(pMu2);
692 iTer++;
693 }
694 while( ( abs(fCosTheta) > 1. || fEmu < fMu ) && iTer < iTerMax );
695
696 if( iTer >= iTerMax ) { fBreak = true; return; }
697
698 if( abs(fCosTheta) > 1.) // vmg: due to big Q2/x values. To be improved ...
699 {
700 G4cout<<"FM: fCosTheta = "<<fCosTheta<<", fEmu = "<<fEmu<<G4endl;
701 // fCosTheta = -1. + 2.*G4UniformRand();
702 if( fCosTheta < -1.) fCosTheta = -1.;
703 if( fCosTheta > 1.) fCosTheta = 1.;
704 }
705 // LVs
706 // G4LorentzVector lvt1 = G4LorentzVector( 0., 0., 0., mN ); // fM1 );
707
708 G4LorentzVector lvt1 = G4LorentzVector( 0., 0., 0., fM1 ); // fM1 );
709 G4LorentzVector lvsum = lvp1 + lvt1;
710
711 cost = fCosTheta;
712 sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
713 phi = G4UniformRand()*CLHEP::twopi;
714 eP = G4ThreeVector( sint*std::cos(phi), sint*std::sin(phi), cost );
715 muMom = sqrt(fEmu*fEmu-fMu*fMu);
716 eP *= muMom;
717 fLVl = G4LorentzVector( eP, fEmu );
718 fLVh = lvsum - fLVl;
719
720 // if( fLVh.e() < mN || fLVh.m2() < 0.) { fBreak = true; return; }
721
722 if( fLVh.e() < fM1 || fLVh.m2() < 0.) { fBreak = true; return; }
723
724 // back to lab system
725
726 // fLVl.boost(bst);
727 // fLVh.boost(bst);
728 }
729 //G4cout<<iTer<<", "<<fBreak<<"; ";
730 }
731
732 //
733 //
734 ///////////////////////////
735