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25 //
26 //
27 // Geant4 Header : G4NeutrinoElectronCcModel
28 //
29 // Author : V.Grichine 26.4.17
30 //
31
32 #include "G4NeutrinoElectronCcModel.hh"
33 #include "G4SystemOfUnits.hh"
34 #include "G4ParticleTable.hh"
35 #include "G4ParticleDefinition.hh"
36 #include "G4IonTable.hh"
37 #include "Randomize.hh"
38 #include "G4NeutrinoE.hh"
39 #include "G4AntiNeutrinoE.hh"
40
41 #include "G4NeutrinoMu.hh"
42 #include "G4AntiNeutrinoMu.hh"
43 #include "G4NeutrinoTau.hh"
44 #include "G4AntiNeutrinoTau.hh"
45 #include "G4MuonMinus.hh"
46 #include "G4TauMinus.hh"
47 #include "G4HadronicParameters.hh"
48 #include "G4PhysicsModelCatalog.hh"
49
50 using namespace std;
51 using namespace CLHEP;
52
53 G4NeutrinoElectronCcModel::G4NeutrinoElectronCcModel(const G4String& name)
54 : G4HadronicInteraction(name)
55 {
56 SetMinEnergy( 0.0*GeV );
57 SetMaxEnergy( G4HadronicParameters::Instance()->GetMaxEnergy() );
58 SetMinEnergy(1.e-6*eV);
59
60 theNeutrinoE = G4NeutrinoE::NeutrinoE();
61 theAntiNeutrinoE = G4AntiNeutrinoE::AntiNeutrinoE();
62
63 theNeutrinoMu = G4NeutrinoMu::NeutrinoMu();
64 theAntiNeutrinoMu = G4AntiNeutrinoMu::AntiNeutrinoMu();
65
66 theNeutrinoTau = G4NeutrinoTau::NeutrinoTau();
67 theAntiNeutrinoTau = G4AntiNeutrinoTau::AntiNeutrinoTau();
68
69 theMuonMinus = G4MuonMinus::MuonMinus();
70 theTauMinus = G4TauMinus::TauMinus();
71
72 // PDG2016: sin^2 theta Weinberg
73
74 fSin2tW = 0.23129; // 0.2312;
75
76 fCutEnergy = 0.; // default value
77
78 // Creator model ID
79 secID = G4PhysicsModelCatalog::GetModelID( "model_" + GetModelName() );
80 }
81
82
83 G4NeutrinoElectronCcModel::~G4NeutrinoElectronCcModel()
84 {}
85
86
87 void G4NeutrinoElectronCcModel::ModelDescription(std::ostream& outFile) const
88 {
89
90 outFile << "G4NeutrinoElectronCcModel is a neutrino-electron (neutral current) elastic scattering\n"
91 << "model which uses the standard model \n"
92 << "transfer parameterization. The model is fully relativistic\n";
93
94 }
95
96 /////////////////////////////////////////////////////////
97
98 G4bool G4NeutrinoElectronCcModel::IsApplicable(const G4HadProjectile & aPart,
99 G4Nucleus & )
100 {
101 G4bool result = false;
102 G4String pName = aPart.GetDefinition()->GetParticleName();
103 if(pName == "anti_nu_mu" || pName == "anti_nu_tau") return result; // no cc for anti_nu_(mu,tau)
104 G4double minEnergy = 0., energy = aPart.GetTotalEnergy();
105 G4double fmass, emass = electron_mass_c2;
106
107 if( pName == "nu_mu" ) fmass = theMuonMinus->GetPDGMass();
108 else if( pName == "nu_tau" ) fmass = theTauMinus->GetPDGMass();
109 else fmass = emass;
110
111 minEnergy = (fmass-emass)*(fmass+emass)/emass;
112 SetMinEnergy( minEnergy );
113
114 if( ( pName == "nu_mu" || pName == "nu_tau" || pName == "anti_nu_e" ) && energy > minEnergy )
115 {
116 result = true;
117 }
118
119 return result;
120 }
121
122 ////////////////////////////////////////////////
123 //
124 //
125
126 G4HadFinalState* G4NeutrinoElectronCcModel::ApplyYourself(
127 const G4HadProjectile& aTrack, G4Nucleus& )
128 {
129 theParticleChange.Clear();
130
131 const G4HadProjectile* aParticle = &aTrack;
132 G4double energy = aParticle->GetTotalEnergy();
133
134 G4String pName = aParticle->GetDefinition()->GetParticleName();
135 G4double minEnergy(0.), fmass(0.), emass = electron_mass_c2;
136
137 if( pName == "nu_mu" ) fmass = theMuonMinus->GetPDGMass();
138 else if( pName == "nu_tau" ) fmass = theTauMinus->GetPDGMass();
139 else fmass = emass;
140
141 minEnergy = (fmass-emass)*(fmass+emass)/emass;
142
143 if( energy <= minEnergy )
144 {
145 theParticleChange.SetEnergyChange(energy);
146 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
147 return &theParticleChange;
148 }
149 G4double massf(0.), massf2(0.); // , emass = electron_mass_c2;
150 G4double sTot = 2.*energy*emass + emass*emass;
151
152 G4LorentzVector lvp1 = aParticle->Get4Momentum();
153 G4LorentzVector lvt1(0.,0.,0.,electron_mass_c2);
154 G4LorentzVector lvsum = lvp1+lvt1;
155 G4ThreeVector bst = lvsum.boostVector();
156
157 // sample and make final state in CMS frame
158
159 G4double cost = SampleCosCMS( aParticle );
160 G4double sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
161 G4double phi = G4UniformRand()*CLHEP::twopi;
162
163 G4ThreeVector eP( sint*std::cos(phi), sint*std::sin(phi), cost );
164
165 if( pName == "nu_mu" ) massf = theMuonMinus->GetPDGMass();
166 else if( pName == "nu_tau" ) massf = theTauMinus->GetPDGMass();
167
168 massf2 = massf*massf;
169
170 G4double epf = 0.5*(sTot - massf2)/sqrt(sTot);
171 // G4double etf = epf*(sTot + massf2)/(sTot - massf2);
172
173 eP *= epf;
174 G4LorentzVector lvp2( eP, epf );
175 lvp2.boost(bst); // back to lab frame
176
177 G4LorentzVector lvt2 = lvsum - lvp2; // ?
178
179 G4DynamicParticle* aNu = nullptr;
180 G4DynamicParticle* aLept = nullptr;
181
182 if( pName == "nu_mu" || pName == "nu_tau")
183 {
184 aNu = new G4DynamicParticle( theNeutrinoE, lvp2 );
185 }
186 else if( pName == "anti_nu_e" ) aNu = new G4DynamicParticle( theAntiNeutrinoMu, lvp2 ); // s-channel for mu (tau later)
187
188 if( pName == "nu_mu" || pName == "anti_nu_e")
189 {
190 aLept = new G4DynamicParticle( theMuonMinus, lvt2 );
191 }
192 else if( pName == "nu_tau" ) // || pName == "anti_nu_tau")
193 {
194 aLept = new G4DynamicParticle( theTauMinus, lvt2 );
195 }
196 if(aNu) { theParticleChange.AddSecondary( aNu, secID ); }
197 if(aLept) { theParticleChange.AddSecondary( aLept, secID ); }
198
199 return &theParticleChange;
200 }
201
202 //////////////////////////////////////////////////////
203 //
204 // sample recoil electron energy in lab frame
205
206 G4double G4NeutrinoElectronCcModel::SampleCosCMS(const G4HadProjectile* aParticle)
207 {
208 G4double result = 0., cofL, cofR, cofLR, massf2, sTot, emass = electron_mass_c2, emass2;
209
210 G4double energy = aParticle->GetTotalEnergy();
211
212 if( energy == 0.) return result; // vmg: < th?? as in xsc
213
214 G4String pName = aParticle->GetDefinition()->GetParticleName();
215
216 if( pName == "nu_mu" || pName == "nu_tau")
217 {
218 return 2.*G4UniformRand()-1.; // uniform scattering cos in CMS
219 }
220 else if( pName == "anti_nu_mu" || pName == "anti_nu_tau")
221 {
222 emass2 = emass*emass;
223 sTot = 2.*energy*emass + emass2;
224
225 cofL = (sTot-emass2)/(sTot+emass2);
226
227 if(pName == "anti_nu_mu") massf2 = theMuonMinus->GetPDGMass()*theMuonMinus->GetPDGMass();
228 else massf2 = theTauMinus->GetPDGMass()*theTauMinus->GetPDGMass();
229
230 cofR = (sTot-massf2)/(sTot+massf2);
231
232 cofLR = cofL*cofR/3.;
233
234 // cofs of cos 3rd equation
235
236 G4double a = cofLR;
237 G4double b = 0.5*(cofR+cofL);
238 G4double c = 1.;
239
240 G4double d = -G4UniformRand()*2.*(1.+ cofLR);
241 d += c - b + a;
242
243 // G4cout<<a<<" "<<b<<" "<<c<<" "<<d<<G4endl<<G4endl;
244
245 // cofs of the incomplete 3rd equation
246
247 G4double p = c/a;
248 p -= b*b/a/a/3.;
249
250 G4double q = d/a;
251 q -= b*c/a/a/3.;
252 q += 2*b*b*b/a/a/a/27.;
253
254
255 // cofs for the incomplete colutions
256
257 G4double D = p*p*p/3./3./3.;
258 D += q*q/2./2.;
259
260 // G4cout<<"D = "<<D<<G4endl;
261 if(D < 0.) D = -D;
262 // G4complex A1 = G4complex(- q/2., std::sqrt(-D) );
263 // G4complex A = std::pow(A1,1./3.);
264
265 // G4complex B1 = G4complex(- q/2., -std::sqrt(-D) );
266 // G4complex B = std::pow(B1,1./3.);
267
268 G4double A, B;
269
270 G4double A1 = - q/2. + std::sqrt(D);
271 if (A1 < 0.) A1 = -A1;
272 A = std::pow(A1,1./3.);
273 if (A1 < 0.) A = -A;
274
275 G4double B1 = - q/2. - std::sqrt(D);
276 // G4double B = std::pow(-B1,1./3.);
277 if(B1 < 0.) B1 = -B1;
278 B = std::pow(B1,1./3.);
279 if(B1 < 0.) B = -B;
280 // G4cout<<"A1 = "<<A1<<"; A = "<<A<<"; B1 = "<<B1<<"; B = "<<B<<G4endl;
281 // roots of the incomplete 3rd equation
282
283 G4complex y1 = A + B;
284 // G4complex y2 = -0.5*(A + B) + 0.5*std::sqrt(3.)*(A - B)*G4complex(0.,1.);
285 // G4complex y3 = -0.5*(A + B) - 0.5*std::sqrt(3.)*(A - B)*G4complex(0.,1.);
286
287 G4complex x1 = y1 - b/a/3.;
288 // G4complex x2 = y2 - b/a/3.;
289 // G4complex x3 = y3 - b/a/3.;
290 // G4cout<<"re_x1 = "<<real(x1)<<" + i*"<<imag(x1)<<G4endl;
291 // G4cout<<"re_x1 = "<<real(x1)<<"; re_x2 = "<<real(x2)<<"; re_x3 = "<<real(x3)<<G4endl;
292 // G4cout<<"im_x1 = "<<imag(x1)<<"; im_x2 = "<<imag(x2)<<"; im_x3 = "<<imag(x3)<<G4endl<<G4endl;
293
294 result = real(x1);
295 }
296 else
297 {
298 return result;
299 }
300 return result;
301 }
302
303 //
304 //
305 ///////////////////////////
306