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26 #include "G4QGSMSplitableHadron.hh" 26 #include "G4QGSMSplitableHadron.hh"
27 #include "G4PhysicalConstants.hh" 27 #include "G4PhysicalConstants.hh"
28 #include "G4SystemOfUnits.hh" 28 #include "G4SystemOfUnits.hh"
29 #include "G4ParticleTable.hh" 29 #include "G4ParticleTable.hh"
30 #include "G4PionPlus.hh" 30 #include "G4PionPlus.hh"
31 #include "G4PionMinus.hh" 31 #include "G4PionMinus.hh"
32 #include "G4Gamma.hh" 32 #include "G4Gamma.hh"
33 #include "G4PionZero.hh" 33 #include "G4PionZero.hh"
34 #include "G4KaonPlus.hh" 34 #include "G4KaonPlus.hh"
35 #include "G4KaonMinus.hh" 35 #include "G4KaonMinus.hh"
36 36
37 #include "G4Log.hh" <<
38 #include "G4Pow.hh" <<
39 <<
40 // based on prototype by Maxim Komogorov 37 // based on prototype by Maxim Komogorov
41 // Splitting into methods, and centralizing of 38 // Splitting into methods, and centralizing of model parameters HPW Feb 1999
42 // restructuring HPW Feb 1999 39 // restructuring HPW Feb 1999
43 // fixing bug in the sampling of 'x', HPW Feb 40 // fixing bug in the sampling of 'x', HPW Feb 1999
44 // fixing bug in sampling pz, HPW Feb 1999. 41 // fixing bug in sampling pz, HPW Feb 1999.
45 // Code now also good for p-nucleus scattering 42 // Code now also good for p-nucleus scattering (before only p-p), HPW Feb 1999.
46 // Using Parton more directly, HPW Feb 1999. 43 // Using Parton more directly, HPW Feb 1999.
47 // Shortening the algorithm for sampling x, HP 44 // Shortening the algorithm for sampling x, HPW Feb 1999.
48 // sampling of x replaced by formula, taking X 45 // sampling of x replaced by formula, taking X_min into account in the correlated sampling. HPW, Feb 1999.
49 // logic much clearer now. HPW Feb 1999 46 // logic much clearer now. HPW Feb 1999
50 // Removed the ordering problem. No Direction 47 // Removed the ordering problem. No Direction needed in selection of valence quark types. HPW Mar'99.
51 // Fixing p-t distributions for scattering of 48 // Fixing p-t distributions for scattering of nuclei.
52 // Separating out parameters. 49 // Separating out parameters.
53 50
54 void G4QGSMSplitableHadron::InitParameters() 51 void G4QGSMSplitableHadron::InitParameters()
55 { 52 {
56 // changing rapidity distribution for all << 53 // changing rapidity distribution for all
57 alpha = -0.5; // Note that this number is st << 54 alpha = -0.5; // Note that this number is still assumed in the algorithm
58 // needs to be generalized. << 55 // needs to be generalized.
59 // changing rapidity distribution for projec << 56 // changing rapidity distribution for projectile like
60 beta = 2.5;// Note that this number is still << 57 beta = 2.5;// Note that this number is still assumed in the algorithm
61 // needs to be generalized. << 58 // needs to be generalized.
62 theMinPz = 0.5*G4PionMinus::PionMinus()->Get << 59 theMinPz = 0.5*G4PionMinus::PionMinus()->GetPDGMass();
63 // theMinPz = 0.1*G4PionMinus::PionMinus()- << 60 // theMinPz = 0.1*G4PionMinus::PionMinus()->GetPDGMass();
64 // theMinPz = G4PionMinus::PionMinus()->Get << 61 // theMinPz = G4PionMinus::PionMinus()->GetPDGMass();
65 // as low as possible, otherwise, we have un << 62 // as low as possible, otherwise, we have unphysical boundary conditions in the sampling.
66 StrangeSuppress = 0.48; << 63 StrangeSuppress = 0.48;
67 sigmaPt = 0.*GeV; // widens eta slightly, if << 64 sigmaPt = 0.*GeV; // widens eta slightly, if increased to 1.7,
68 // but Maxim's algorithm breaks energy conse << 65 // but Maxim's algorithm breaks energy conservation
69 widthOfPtSquare = 0.5*sqr(GeV); << 66 // to be revised.
70 Direction = FALSE; << 67 widthOfPtSquare = 0.01*GeV*GeV;
71 minTransverseMass = 1*keV; << 68 Direction = FALSE;
72 iP =0;// Color.begin(); << 69 minTransverseMass = 1*keV;
73 iAP =0;// AntiColor.begin(); <<
74 } 70 }
75 71
76 G4QGSMSplitableHadron::G4QGSMSplitableHadron() 72 G4QGSMSplitableHadron::G4QGSMSplitableHadron()
77 { 73 {
78 InitParameters(); << 74 InitParameters();
79 } 75 }
80 76
81 G4QGSMSplitableHadron::G4QGSMSplitableHadron(c 77 G4QGSMSplitableHadron::G4QGSMSplitableHadron(const G4ReactionProduct & aPrimary, G4bool aDirection)
82 :G4VSplitableHadron(aPrimary) 78 :G4VSplitableHadron(aPrimary)
83 { 79 {
84 InitParameters(); << 80 InitParameters();
85 Direction = aDirection; << 81 Direction = aDirection;
86 } 82 }
87 83
88 84
89 G4QGSMSplitableHadron::G4QGSMSplitableHadron(c 85 G4QGSMSplitableHadron::G4QGSMSplitableHadron(const G4ReactionProduct & aPrimary)
90 : G4VSplitableHadron(aPrimary) 86 : G4VSplitableHadron(aPrimary)
91 { 87 {
92 InitParameters(); << 88 InitParameters();
93 } 89 }
94 90
95 G4QGSMSplitableHadron::G4QGSMSplitableHadron(c 91 G4QGSMSplitableHadron::G4QGSMSplitableHadron(const G4Nucleon & aNucleon)
96 : G4VSplitableHadron(aNucleon) 92 : G4VSplitableHadron(aNucleon)
97 { 93 {
98 InitParameters(); << 94 InitParameters();
99 } 95 }
100 96
101 G4QGSMSplitableHadron::G4QGSMSplitableHadron(c 97 G4QGSMSplitableHadron::G4QGSMSplitableHadron(const G4Nucleon & aNucleon, G4bool aDirection)
102 : G4VSplitableHadron(aNucleon) 98 : G4VSplitableHadron(aNucleon)
103 { 99 {
104 InitParameters(); << 100 InitParameters();
105 Direction = aDirection; << 101 Direction = aDirection;
106 } 102 }
107 103
108 G4QGSMSplitableHadron::~G4QGSMSplitableHadron( << 104 G4QGSMSplitableHadron::~G4QGSMSplitableHadron(){}
>> 105
109 106
110 107
111 //******************************************** 108 //**************************************************************************************************************************
112 109
113 void G4QGSMSplitableHadron::SplitUp() 110 void G4QGSMSplitableHadron::SplitUp()
114 { 111 {
115 if (IsSplit()) return; << 112 if (IsSplit()) return;
116 Splitting(); // To mark that a hadron is sp << 113 Splitting();
117 if (Color.size()!=0) return; << 114 if (Color.size()!=0) return;
118 if (GetSoftCollisionCount() == 0) // GetSof << 115 if (GetSoftCollisionCount() == 0)
119 { << 116 {
120 DiffractiveSplitUp(); << 117 DiffractiveSplitUp();
121 } << 118 }
122 else << 119 else
123 { << 120 {
124 SoftSplitUp(); << 121 SoftSplitUp();
125 } << 122 }
126 } 123 }
127 124
128 void G4QGSMSplitableHadron::DiffractiveSplitUp 125 void G4QGSMSplitableHadron::DiffractiveSplitUp()
129 { 126 {
130 // take the particle definitions and get the << 127 // take the particle definitions and get the partons HPW
131 G4Parton * Left = NULL; << 128 G4Parton * Left = NULL;
132 G4Parton * Right = NULL; << 129 G4Parton * Right = NULL;
133 GetValenceQuarkFlavors(GetDefinition(), Left << 130 GetValenceQuarkFlavors(GetDefinition(), Left, Right);
134 Left->SetPosition(GetPosition()); << 131 Left->SetPosition(GetPosition());
135 Right->SetPosition(GetPosition()); << 132 Right->SetPosition(GetPosition());
136 << 133
137 G4LorentzVector HadronMom = Get4Momentum(); << 134 G4LorentzVector HadronMom = Get4Momentum();
138 << 135 //std::cout << "DSU 1 - "<<HadronMom<<std::endl;
139 G4double maxAvailMomentum2 = sqr(HadronMom.m << 136
140 << 137 // momenta of string ends
141 G4ThreeVector pt(minTransverseMass, minTrans << 138 G4double pt2 = HadronMom.perp2();
142 if (maxAvailMomentum2/widthOfPtSquare>0.01) << 139 G4double transverseMass2 = HadronMom.plus()*HadronMom.minus();
143 << 140 G4double maxAvailMomentum2 = sqr(std::sqrt(transverseMass2) - std::sqrt(pt2));
144 G4LorentzVector LeftMom(pt, 0.); << 141 G4ThreeVector pt(minTransverseMass, minTransverseMass, 0);
145 G4LorentzVector RightMom; << 142 if(maxAvailMomentum2/widthOfPtSquare>0.01) pt = GaussianPt(widthOfPtSquare, maxAvailMomentum2);
146 RightMom.setPx(HadronMom.px() - pt.x()); << 143 //std::cout << "DSU 1.1 - "<< maxAvailMomentum2<< pt <<std::endl;
147 RightMom.setPy(HadronMom.py() - pt.y()); << 144
148 << 145 G4LorentzVector LeftMom(pt, 0.);
149 G4double Local1 = HadronMom.minus() + (Right << 146 G4LorentzVector RightMom;
150 G4double Local2 = std::sqrt(std::max(0., sqr << 147 RightMom.setPx(HadronMom.px() - pt.x());
151 << 148 RightMom.setPy(HadronMom.py() - pt.y());
152 if (Direction) Local2 = -Local2; << 149 //std::cout << "DSU 2 - "<<RightMom<<" "<< LeftMom <<std::endl;
153 G4double RightMinus = 0.5*(Local1 + Local2 << 150
154 G4double LeftMinus = HadronMom.minus() - Rig << 151 G4double Local1 = HadronMom.minus() + (RightMom.perp2() - LeftMom.perp2())/HadronMom.plus();
155 << 152 G4double Local2 = std::sqrt(std::max(0., sqr(Local1) - 4.*RightMom.perp2()*HadronMom.minus()/HadronMom.plus()));
156 if (LeftMinus <= 0.) { << 153 //std::cout << "DSU 3 - "<< Local1 <<" "<< Local2 <<std::endl;
157 RightMinus = 0.5*(Local1 - Local2); << 154 if (Direction) Local2 = -Local2;
158 LeftMinus = HadronMom.minus() - RightMinus << 155 G4double RightMinus = 0.5*(Local1 + Local2);
159 } << 156 G4double LeftMinus = HadronMom.minus() - RightMinus;
160 << 157 //std::cout << "DSU 4 - "<< RightMinus <<" "<< LeftMinus << " "<<HadronMom.minus() <<std::endl;
161 G4double LeftPlus = LeftMom.perp2()/LeftMin << 158
162 G4double RightPlus = HadronMom.plus() - Left << 159 G4double LeftPlus = LeftMom.perp2()/LeftMinus;
163 << 160 G4double RightPlus = HadronMom.plus() - LeftPlus;
164 LeftMom.setPz(0.5*(LeftPlus - LeftMinus)); << 161 //std::cout << "DSU 5 - "<< RightPlus <<" "<< LeftPlus <<std::endl;
165 LeftMom.setE (0.5*(LeftPlus + LeftMinus)); << 162 LeftMom.setPz(0.5*(LeftPlus - LeftMinus));
166 RightMom.setPz(0.5*(RightPlus - RightMinus)) << 163 LeftMom.setE (0.5*(LeftPlus + LeftMinus));
167 RightMom.setE (0.5*(RightPlus + RightMinus)) << 164 RightMom.setPz(0.5*(RightPlus - RightMinus));
168 << 165 RightMom.setE (0.5*(RightPlus + RightMinus));
169 Left->Set4Momentum(LeftMom); << 166 //std::cout << "DSU 6 - "<< LeftMom <<" "<< RightMom <<std::endl;
170 Right->Set4Momentum(RightMom); << 167 Left->Set4Momentum(LeftMom);
171 << 168 Right->Set4Momentum(RightMom);
172 Color.push_back(Left); << 169 Color.push_back(Left);
173 AntiColor.push_back(Right); << 170 AntiColor.push_back(Right);
174 iP=0; iAP=0; <<
175 } 171 }
176 172
177 173
178 void G4QGSMSplitableHadron::SoftSplitUp() 174 void G4QGSMSplitableHadron::SoftSplitUp()
179 { 175 {
180 G4int nSeaPair = GetSoftCollisionCount()-1; << 176 //... sample transversal momenta for sea and valence quarks
181 << 177 G4double phi, pts;
182 G4LorentzVector tmp(0., 0., 0., 0.); << 178 G4double SumPy = 0.;
183 << 179 G4double SumPx = 0.;
184 G4int aSeaPair; << 180 G4ThreeVector Pos = GetPosition();
185 for (aSeaPair = 0; aSeaPair < nSeaPair; aSea << 181 G4int nSeaPair = GetSoftCollisionCount()-1;
186 { << 182
187 // choose quark flavour, d:u:s = 1:1:(1/S << 183 // here the condition,to ensure viability of splitting, also in cases
188 G4int aPDGCode = 1 + (G4int)(G4UniformRand << 184 // where difractive excitation occured together with soft scattering.
189 << 185 // G4double LightConeMomentum = (Direction)? Get4Momentum().plus() : Get4Momentum().minus();
190 // BuildSeaQuark() determines quark spin, << 186 // G4double Xmin = theMinPz/LightConeMomentum;
191 // via parton-constructor G4Parton(aPDGCo << 187 G4double Xmin = theMinPz/( Get4Momentum().e() - GetDefinition()->GetPDGMass() );
192 G4Parton * aParton = BuildSeaQuark(false, << 188 while(Xmin>=1-(2*nSeaPair+1)*Xmin) Xmin*=0.95;
193 << 189
194 G4int firstPartonColour = aParton->GetColo << 190 G4int aSeaPair;
195 G4double firstPartonSpinZ = aParton->GetSp << 191 for (aSeaPair = 0; aSeaPair < nSeaPair; aSeaPair++)
196 << 192 {
197 aParton->Set4Momentum(tmp); << 193 // choose quark flavour, d:u:s = 1:1:(1/StrangeSuppress-2)
198 Color.push_back(aParton); << 194
199 << 195 G4int aPDGCode = 1 + (G4int)(G4UniformRand()/StrangeSuppress);
200 // create anti-quark << 196
201 aParton = BuildSeaQuark(true, aPDGCode, nS << 197 // BuildSeaQuark() determines quark spin, isospin and colour
202 aParton->SetSpinZ(-firstPartonSpinZ); << 198 // via parton-constructor G4Parton(aPDGCode)
203 aParton->SetColour(-firstPartonColour); << 199
204 AntiColor.push_back(aParton); << 200 G4Parton * aParton = BuildSeaQuark(false, aPDGCode, nSeaPair);
205 } << 201
206 << 202 // G4cerr << "G4QGSMSplitableHadron::SoftSplitUp()" << G4endl;
207 // Valence quark << 203
208 G4Parton* pColorParton = NULL; << 204 // G4cerr << "Parton 1: "
209 G4Parton* pAntiColorParton = NULL; << 205 // << " PDGcode: " << aPDGCode
210 GetValenceQuarkFlavors(GetDefinition(), pCol << 206 // << " - Name: " << aParton->GetDefinition()->GetParticleName()
211 << 207 // << " - Type: " << aParton->GetDefinition()->GetParticleType()
212 pColorParton->Set4Momentum(tmp); << 208 // << " - Spin-3: " << aParton->GetSpinZ()
213 pAntiColorParton->Set4Momentum(tmp); << 209 // << " - Colour: " << aParton->GetColour() << G4endl;
214 << 210
215 Color.push_back(pColorParton); << 211 // save colour a spin-3 for anti-quark
216 AntiColor.push_back(pAntiColorParton); << 212
217 << 213 G4int firstPartonColour = aParton->GetColour();
218 iP=0; iAP=0; << 214 G4double firstPartonSpinZ = aParton->GetSpinZ();
219 << 215
220 return; << 216 SumPx += aParton->Get4Momentum().px();
>> 217 SumPy += aParton->Get4Momentum().py();
>> 218 Color.push_back(aParton);
>> 219
>> 220 // create anti-quark
>> 221
>> 222 aParton = BuildSeaQuark(true, aPDGCode, nSeaPair);
>> 223 aParton->SetSpinZ(-firstPartonSpinZ);
>> 224 aParton->SetColour(-firstPartonColour);
>> 225
>> 226 // G4cerr << "Parton 2: "
>> 227 // << " PDGcode: " << -aPDGCode
>> 228 // << " - Name: " << aParton->GetDefinition()->GetParticleName()
>> 229 // << " - Type: " << aParton->GetDefinition()->GetParticleType()
>> 230 // << " - Spin-3: " << aParton->GetSpinZ()
>> 231 // << " - Colour: " << aParton->GetColour() << G4endl;
>> 232 // G4cerr << "------------" << G4endl;
>> 233
>> 234 SumPx += aParton->Get4Momentum().px();
>> 235 SumPy += aParton->Get4Momentum().py();
>> 236 AntiColor.push_back(aParton);
>> 237 }
>> 238 // Valence quark
>> 239 G4Parton* pColorParton = NULL;
>> 240 G4Parton* pAntiColorParton = NULL;
>> 241 GetValenceQuarkFlavors(GetDefinition(), pColorParton, pAntiColorParton);
>> 242 G4int ColorEncoding = pColorParton->GetPDGcode();
>> 243
>> 244 pts = sigmaPt*std::sqrt(-std::log(G4UniformRand()));
>> 245 phi = 2.*pi*G4UniformRand();
>> 246 G4double Px = pts*std::cos(phi);
>> 247 G4double Py = pts*std::sin(phi);
>> 248 SumPx += Px;
>> 249 SumPy += Py;
>> 250
>> 251 if (ColorEncoding < 0) // use particle definition
>> 252 {
>> 253 G4LorentzVector ColorMom(-SumPx, -SumPy, 0, 0);
>> 254 pColorParton->Set4Momentum(ColorMom);
>> 255 G4LorentzVector AntiColorMom(Px, Py, 0, 0);
>> 256 pAntiColorParton->Set4Momentum(AntiColorMom);
>> 257 }
>> 258 else
>> 259 {
>> 260 G4LorentzVector ColorMom(Px, Py, 0, 0);
>> 261 pColorParton->Set4Momentum(ColorMom);
>> 262 G4LorentzVector AntiColorMom(-SumPx, -SumPy, 0, 0);
>> 263 pAntiColorParton->Set4Momentum(AntiColorMom);
>> 264 }
>> 265 Color.push_back(pColorParton);
>> 266 AntiColor.push_back(pAntiColorParton);
>> 267
>> 268 // Sample X
>> 269 G4int nAttempt = 0;
>> 270 G4double SumX = 0;
>> 271 G4double aBeta = beta;
>> 272 G4double ColorX, AntiColorX;
>> 273 if (GetDefinition() == G4PionMinus::PionMinusDefinition()) aBeta = 1.;
>> 274 if (GetDefinition() == G4Gamma::GammaDefinition()) aBeta = 1.;
>> 275 if (GetDefinition() == G4PionPlus::PionPlusDefinition()) aBeta = 1.;
>> 276 if (GetDefinition() == G4PionZero::PionZeroDefinition()) aBeta = 1.;
>> 277 if (GetDefinition() == G4KaonPlus::KaonPlusDefinition()) aBeta = 0.;
>> 278 if (GetDefinition() == G4KaonMinus::KaonMinusDefinition()) aBeta = 0.;
>> 279 do
>> 280 {
>> 281 SumX = 0;
>> 282 nAttempt++;
>> 283 G4int NumberOfUnsampledSeaQuarks = 2*nSeaPair;
>> 284 ColorX = SampleX(Xmin, NumberOfUnsampledSeaQuarks, 2*nSeaPair, aBeta);
>> 285 Color.back()->SetX(SumX = ColorX);// this is the valenz quark.
>> 286 for(G4int aPair = 0; aPair < nSeaPair; aPair++)
>> 287 {
>> 288 NumberOfUnsampledSeaQuarks--;
>> 289 ColorX = SampleX(Xmin, NumberOfUnsampledSeaQuarks, 2*nSeaPair, aBeta);
>> 290 Color[aPair]->SetX(ColorX);
>> 291 SumX += ColorX;
>> 292 NumberOfUnsampledSeaQuarks--;
>> 293 AntiColorX = SampleX(Xmin, NumberOfUnsampledSeaQuarks, 2*nSeaPair, aBeta);
>> 294 AntiColor[aPair]->SetX(AntiColorX); // the 'sea' partons
>> 295 SumX += AntiColorX;
>> 296 if (1. - SumX <= Xmin) break;
>> 297 }
>> 298 }
>> 299 while (1. - SumX <= Xmin);
>> 300
>> 301 (*(AntiColor.end()-1))->SetX(1. - SumX); // the di-quark takes the rest, then go to momentum
>> 302 G4double lightCone = ((!Direction) ? Get4Momentum().minus() : Get4Momentum().plus());
>> 303 G4double lightCone2 = ((!Direction) ? Get4Momentum().plus() : Get4Momentum().minus());
>> 304 for(aSeaPair = 0; aSeaPair < nSeaPair+1; aSeaPair++)
>> 305 {
>> 306 G4Parton* aParton = Color[aSeaPair];
>> 307 aParton->DefineMomentumInZ(lightCone, lightCone2, Direction);
>> 308
>> 309 aParton = AntiColor[aSeaPair];
>> 310 aParton->DefineMomentumInZ(lightCone, lightCone2, Direction);
>> 311 }
>> 312 return;
221 } 313 }
222 314
223 << 315 void G4QGSMSplitableHadron::GetValenceQuarkFlavors(const G4ParticleDefinition * aPart, G4Parton *& Parton1, G4Parton *& Parton2)
224 void G4QGSMSplitableHadron::GetValenceQuarkFla <<
225 <<
226 { 316 {
227 // Note! convention aEnd = q or (qq)bar and << 317 // Note! convention aEnd = q or (qq)bar and bEnd = qbar or qq.
228 G4int aEnd=0; << 318 G4int aEnd;
229 G4int bEnd=0; << 319 G4int bEnd;
230 G4int HadronEncoding = aPart->GetPDGEncoding << 320 G4int HadronEncoding = aPart->GetPDGEncoding();
231 if (aPart->GetBaryonNumber() == 0) << 321 if (aPart->GetBaryonNumber() == 0)
232 { << 322 {
233 theMesonSplitter.SplitMeson(HadronEncoding << 323 theMesonSplitter.SplitMeson(HadronEncoding, &aEnd, &bEnd);
234 } << 324 }
235 else << 325 else
236 { << 326 {
237 theBaryonSplitter.SplitBarion(HadronEncodi << 327 theBaryonSplitter.SplitBarion(HadronEncoding, &aEnd, &bEnd);
238 } << 328 }
239 << 329
240 Parton1 = new G4Parton(aEnd); << 330 Parton1 = new G4Parton(aEnd);
241 Parton1->SetPosition(GetPosition()); << 331 Parton1->SetPosition(GetPosition());
242 << 332
243 Parton2 = new G4Parton(bEnd); << 333 // G4cerr << "G4QGSMSplitableHadron::GetValenceQuarkFlavors()" << G4endl;
244 Parton2->SetPosition(GetPosition()); << 334 // G4cerr << "Parton 1: "
245 << 335 // << " PDGcode: " << aEnd
246 // colour of parton 1 choosen at random by G << 336 // << " - Name: " << Parton1->GetDefinition()->GetParticleName()
247 // colour of parton 2 is the opposite: << 337 // << " - Type: " << Parton1->GetDefinition()->GetParticleType()
248 << 338 // << " - Spin-3: " << Parton1->GetSpinZ()
249 Parton2->SetColour(-(Parton1->GetColour())); << 339 // << " - Colour: " << Parton1->GetColour() << G4endl;
250 << 340
251 // isospin-3 of both partons is handled by G << 341 Parton2 = new G4Parton(bEnd);
252 << 342 Parton2->SetPosition(GetPosition());
253 // spin-3 of parton 1 and 2 choosen at rando << 343
254 // spin-3 of parton 2 may be constrained by << 344 // G4cerr << "Parton 2: "
255 << 345 // << " PDGcode: " << bEnd
256 if ( std::abs(Parton1->GetSpinZ() + Parton2- << 346 // << " - Name: " << Parton2->GetDefinition()->GetParticleName()
257 { << 347 // << " - Type: " << Parton2->GetDefinition()->GetParticleType()
258 Parton2->SetSpinZ(-(Parton2->GetSpinZ())); << 348 // << " - Spin-3: " << Parton2->GetSpinZ()
259 } << 349 // << " - Colour: " << Parton2->GetColour() << G4endl;
>> 350 // G4cerr << "... now checking for color and spin conservation - yielding: " << G4endl;
>> 351
>> 352 // colour of parton 1 choosen at random by G4Parton(aEnd)
>> 353 // colour of parton 2 is the opposite:
>> 354
>> 355 Parton2->SetColour(-(Parton1->GetColour()));
>> 356
>> 357 // isospin-3 of both partons is handled by G4Parton(PDGCode)
>> 358
>> 359 // spin-3 of parton 1 and 2 choosen at random by G4Parton(aEnd)
>> 360 // spin-3 of parton 2 may be constrained by spin of original particle:
>> 361
>> 362 if ( std::abs(Parton1->GetSpinZ() + Parton2->GetSpinZ()) > aPart->GetPDGSpin())
>> 363 {
>> 364 Parton2->SetSpinZ(-(Parton2->GetSpinZ()));
>> 365 }
>> 366
>> 367 // G4cerr << "Parton 2: "
>> 368 // << " PDGcode: " << bEnd
>> 369 // << " - Name: " << Parton2->GetDefinition()->GetParticleName()
>> 370 // << " - Type: " << Parton2->GetDefinition()->GetParticleType()
>> 371 // << " - Spin-3: " << Parton2->GetSpinZ()
>> 372 // << " - Colour: " << Parton2->GetColour() << G4endl;
>> 373 // G4cerr << "------------" << G4endl;
>> 374
260 } 375 }
261 376
262 377
263 G4ThreeVector G4QGSMSplitableHadron::GaussianP 378 G4ThreeVector G4QGSMSplitableHadron::GaussianPt(G4double widthSquare, G4double maxPtSquare)
264 { 379 {
265 G4double R; << 380 G4double R;
266 const G4int maxNumberOfLoops = 1000; << 381 while((R = -widthSquare*std::log(G4UniformRand())) > maxPtSquare) {;}
267 G4int loopCounter = -1; << 382 R = std::sqrt(R);
268 while( ((R = -widthSquare*G4Log(G4UniformRan << 383 G4double phi = twopi*G4UniformRand();
269 ++loopCounter < maxNumberOfLoops ) {; << 384 return G4ThreeVector (R*std::cos(phi), R*std::sin(phi), 0.);
270 if ( loopCounter >= maxNumberOfLoops ) { <<
271 R = 0.99*maxPtSquare; // Just an acceptab <<
272 } <<
273 R = std::sqrt(R); <<
274 G4double phi = twopi*G4UniformRand(); <<
275 return G4ThreeVector (R*std::cos(phi), R*std <<
276 } 385 }
277 386
278 <<
279 G4Parton * G4QGSMSplitableHadron:: 387 G4Parton * G4QGSMSplitableHadron::
280 BuildSeaQuark(G4bool isAntiQuark, G4int aPDGCo 388 BuildSeaQuark(G4bool isAntiQuark, G4int aPDGCode, G4int /* nSeaPair*/)
281 { 389 {
282 if (isAntiQuark) aPDGCode*=-1; << 390 if (isAntiQuark) aPDGCode*=-1;
283 G4Parton* result = new G4Parton(aPDGCode); << 391 G4Parton* result = new G4Parton(aPDGCode);
284 result->SetPosition(GetPosition()); << 392 result->SetPosition(GetPosition());
285 G4ThreeVector aPtVector = GaussianPt(sigmaPt << 393 G4ThreeVector aPtVector = GaussianPt(sigmaPt, DBL_MAX);
286 G4LorentzVector a4Momentum(aPtVector, 0); << 394 G4LorentzVector a4Momentum(aPtVector, 0);
287 result->Set4Momentum(a4Momentum); << 395 result->Set4Momentum(a4Momentum);
288 return result; << 396 return result;
289 } 397 }
290 398
291 <<
292 G4double G4QGSMSplitableHadron:: 399 G4double G4QGSMSplitableHadron::
293 SampleX(G4double anXmin, G4int nSea, G4int tot 400 SampleX(G4double anXmin, G4int nSea, G4int totalSea, G4double aBeta)
294 { 401 {
295 G4double result; << 402 G4double result;
296 G4double x1, x2; << 403 G4double x1, x2;
297 G4double ymax = 0; << 404 G4double ymax = 0;
298 for(G4int ii=1; ii<100; ii++) << 405 for(G4int ii=1; ii<100; ii++)
299 { << 406 {
300 G4double y = G4Pow::GetInstance()->powA(1. << 407 G4double y = std::pow(1./G4double(ii), alpha);
301 y *= G4Pow::GetInstance()->powN( G4Pow::Ge << 408 y *= std::pow( std::pow(1-anXmin-totalSea*anXmin, alpha+1) - std::pow(anXmin, alpha+1), nSea);
302 G4Pow::Ge << 409 y *= std::pow(1-anXmin-totalSea*anXmin, aBeta+1) - std::pow(anXmin, aBeta+1);
303 y *= G4Pow::GetInstance()->powA(1-anXmin-t << 410 if(y>ymax) ymax = y;
304 G4Pow::GetInstance()->powA(anXmin, aB << 411 }
305 if (y>ymax) ymax = y; << 412 G4double y;
306 } << 413 G4double xMax=1-(totalSea+1)*anXmin;
307 G4double y; << 414 if(anXmin > xMax)
308 G4double xMax=1-(totalSea+1)*anXmin; << 415 {
309 if (anXmin > xMax) << 416 G4cout << "anXmin = "<<anXmin<<" nSea = "<<nSea<<" totalSea = "<< totalSea<<G4endl;
310 { << 417 throw G4HadronicException(__FILE__, __LINE__, "G4QGSMSplitableHadron - Fatal: Cannot sample parton densities under these constraints.");
311 throw G4HadronicException(__FILE__, __LINE << 418 }
312 "G4QGSMSplitableHadron - Fatal: Ca << 419 do
313 } << 420 {
314 const G4int maxNumberOfLoops = 1000; << 421 x1 = G4RandFlat::shoot(anXmin, xMax);
315 G4int loopCounter = 0; << 422 y = std::pow(x1, alpha);
316 do << 423 y *= std::pow( std::pow(1-x1-totalSea*anXmin, alpha+1) - std::pow(anXmin, alpha+1), nSea);
317 { << 424 y *= std::pow(1-x1-totalSea*anXmin, aBeta+1) - std::pow(anXmin, aBeta+1);
318 x1 = G4RandFlat::shoot(anXmin, xMax); << 425 x2 = ymax*G4UniformRand();
319 y = G4Pow::GetInstance()->powA(x1, alpha); << 426 }
320 y *= G4Pow::GetInstance()->powN( G4Pow::Ge << 427 while(x2>y);
321 G4Pow::Ge << 428 result = x1;
322 y *= G4Pow::GetInstance()->powA(1-x1-total << 429 return result;
323 G4Pow::GetInstance()->powA(anXmin, aB <<
324 x2 = ymax*G4UniformRand(); <<
325 } while( (x2>y) && ++loopCounter < maxNumber <<
326 if ( loopCounter >= maxNumberOfLoops ) { <<
327 x1 = 0.5*( anXmin + xMax ); // Just an ac <<
328 } <<
329 result = x1; <<
330 return result; <<
331 } 430 }
332 431