1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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7 | // * conditions of the Geant4 Software License, included in the file * |
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8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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9 | // * include a list of copyright holders. * |
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10 | // * * |
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11 | // * Neither the authors of this software system, nor their employing * |
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12 | // * institutes,nor the agencies providing financial support for this * |
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13 | // * work make any representation or warranty, express or implied, * |
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14 | // * regarding this software system or assume any liability for its * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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16 | // * for the full disclaimer and the limitation of liability. * |
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17 | // * * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration. * |
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20 | // * By using, copying, modifying or distributing the software (or * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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22 | // * use in resulting scientific publications, and indicate your * |
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23 | // * acceptance of all terms of the Geant4 Software license. * |
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24 | // ******************************************************************** |
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25 | // |
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26 | #include "globals.hh" |
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27 | #include "G4ios.hh" |
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28 | #include "G4XAnnihilationChannel.hh" |
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29 | #include "G4KineticTrack.hh" |
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30 | #include "G4ParticleDefinition.hh" |
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31 | #include "G4ResonanceWidth.hh" |
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32 | #include "G4ResonancePartialWidth.hh" |
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33 | #include "G4PhysicsVector.hh" |
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34 | #include "G4PartialWidthTable.hh" |
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35 | |
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36 | G4XAnnihilationChannel::G4XAnnihilationChannel(): resonance(0) |
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37 | { } |
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38 | |
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39 | G4XAnnihilationChannel::G4XAnnihilationChannel(const G4ParticleDefinition* resDefinition, |
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40 | const G4ResonanceWidth& resWidths, |
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41 | const G4ResonancePartialWidth& resPartWidths, |
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42 | const G4String& partWidthLabel) |
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43 | : resonance(resDefinition) |
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44 | { |
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45 | // Get the tabulated mass-dependent widths for the resonance |
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46 | G4String resName = resonance->GetParticleName(); |
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47 | // cout << "HPW "<<resName<<endl; |
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48 | G4String shortName = theNames.ShortName(resName); |
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49 | // cout << "HPW "<<shortName<<endl; |
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50 | // cout << "HPW "<<partWidthLabel<<endl; |
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51 | |
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52 | widthTable = resWidths.MassDependentWidth(shortName); |
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53 | partWidthTable = resPartWidths.MassDependentWidth(partWidthLabel); |
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54 | |
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55 | // As a first approximation the model is assumed to be valid over |
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56 | // the entire energy range |
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57 | lowLimit = 0.; |
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58 | highLimit = DBL_MAX; |
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59 | } |
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60 | |
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61 | |
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62 | G4XAnnihilationChannel::~G4XAnnihilationChannel() |
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63 | { |
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64 | delete widthTable; |
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65 | widthTable = 0; |
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66 | delete partWidthTable; |
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67 | partWidthTable = 0; |
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68 | } |
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69 | |
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70 | |
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71 | G4bool G4XAnnihilationChannel::operator==(const G4XAnnihilationChannel &right) const |
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72 | { |
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73 | return (this == (G4XAnnihilationChannel *) &right); |
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74 | } |
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75 | |
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76 | |
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77 | G4bool G4XAnnihilationChannel::operator!=(const G4XAnnihilationChannel &right) const |
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78 | { |
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79 | return (this != (G4XAnnihilationChannel *) &right); |
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80 | } |
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81 | |
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82 | |
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83 | G4double G4XAnnihilationChannel::CrossSection(const G4KineticTrack& trk1, |
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84 | const G4KineticTrack& trk2) const |
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85 | { |
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86 | G4double sigma = 0.; |
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87 | G4double eCM = (trk1.Get4Momentum() + trk2.Get4Momentum()).mag(); |
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88 | |
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89 | G4ParticleDefinition* def1 = trk1.GetDefinition(); |
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90 | G4ParticleDefinition* def2 = trk2.GetDefinition(); |
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91 | |
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92 | G4int J1 = def1->GetPDGiSpin(); |
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93 | G4int J2 = def2->GetPDGiSpin(); |
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94 | G4double m1 = def1->GetPDGMass(); |
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95 | G4double m2 = def2->GetPDGMass(); |
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96 | |
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97 | G4int JRes = resonance->GetPDGiSpin(); |
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98 | G4double mRes = resonance->GetPDGMass(); |
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99 | |
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100 | G4double branch = Branch(trk1,trk2); |
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101 | G4double width = VariableWidth(trk1,trk2); |
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102 | G4double cleb = NormalizedClebsch(trk1,trk2); |
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103 | |
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104 | G4double s = eCM * eCM; |
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105 | if (s == 0.) throw G4HadronicException(__FILE__, __LINE__, "G4XAnnihilationChannel::CrossSection - eCM = 0"); |
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106 | |
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107 | G4double pCM = std::sqrt((s-(m1+m2)*(m1+m2))*(s-(m1-m2)*(m1-m2))/(4.*s)); |
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108 | |
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109 | sigma = ( (JRes + 1.) / ( (J1 + 1) * (J2 + 1) ) |
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110 | * pi / (pCM * pCM) * branch * width * width / |
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111 | ( (eCM - mRes) * (eCM - mRes) + width * width / 4.0) * cleb * hbarc_squared); |
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112 | |
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113 | // G4cout << "SS " << branch<<" "<<sigma<<" " |
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114 | // << J1 <<" " |
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115 | // <<J2<<" " |
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116 | // <<m1<<" " |
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117 | // <<m2<<" " |
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118 | // <<JRes<<" " |
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119 | // <<mRes<<" " |
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120 | // <<wRes<<" " |
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121 | // <<width<<" " |
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122 | // <<cleb<<" " |
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123 | // <<G4endl; |
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124 | return sigma; |
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125 | } |
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126 | |
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127 | |
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128 | G4String G4XAnnihilationChannel::Name() const |
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129 | { |
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130 | G4String name("XAnnihilationChannelCrossSection"); |
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131 | return name; |
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132 | } |
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133 | |
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134 | |
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135 | |
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136 | G4bool G4XAnnihilationChannel::IsValid(G4double e) const |
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137 | { |
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138 | G4bool answer = InLimits(e,lowLimit,highLimit); |
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139 | |
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140 | return answer; |
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141 | } |
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142 | |
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143 | |
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144 | G4double G4XAnnihilationChannel::Branch(const G4KineticTrack& trk1, |
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145 | const G4KineticTrack& trk2) const |
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146 | { |
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147 | G4double w=VariableWidth(trk1,trk2); |
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148 | if(w==0) return 0; |
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149 | return VariablePartialWidth(trk1,trk2) / VariableWidth(trk1,trk2); |
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150 | } |
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151 | |
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152 | G4double G4XAnnihilationChannel::VariableWidth(const G4KineticTrack& trk1, |
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153 | const G4KineticTrack& trk2) const |
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154 | { |
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155 | // actual production width of resonance, depending on available energy. |
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156 | |
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157 | G4double width = resonance->GetPDGWidth(); |
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158 | G4bool dummy = false; |
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159 | G4double sqrtS = (trk1.Get4Momentum() + trk2.Get4Momentum()).mag(); |
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160 | if (widthTable != 0) |
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161 | { |
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162 | width = widthTable->GetValue(sqrtS,dummy); |
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163 | } |
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164 | return width; |
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165 | } |
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166 | |
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167 | |
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168 | G4double G4XAnnihilationChannel::VariablePartialWidth(const G4KineticTrack& trk1, |
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169 | const G4KineticTrack& trk2) const |
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170 | { |
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171 | // Calculate mass dependent partial width of resonance, |
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172 | // based on UrQMD tabulations |
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173 | |
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174 | G4double width(0); |
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175 | |
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176 | if (partWidthTable != 0) |
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177 | { |
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178 | G4double sqrtS = 0; |
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179 | G4bool dummy = false; |
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180 | sqrtS = (trk1.Get4Momentum() + trk2.Get4Momentum()).mag(); |
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181 | width = partWidthTable->GetValue(sqrtS,dummy); |
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182 | } |
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183 | else |
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184 | { |
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185 | width = resonance->GetPDGWidth(); |
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186 | } |
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187 | return width; |
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188 | } |
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189 | |
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190 | |
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191 | G4double G4XAnnihilationChannel::NormalizedClebsch(const G4KineticTrack& trk1, |
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192 | const G4KineticTrack& trk2) const |
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193 | { |
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194 | G4double cleb = 0.; |
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195 | G4ParticleDefinition* def1 = trk1.GetDefinition(); |
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196 | G4ParticleDefinition* def2 = trk2.GetDefinition(); |
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197 | |
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198 | G4int iso31 = def1->GetPDGiIsospin3(); |
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199 | G4int iso32 = def2->GetPDGiIsospin3(); |
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200 | G4int iso3 = iso31 + iso32; |
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201 | G4int iso1 = def1->GetPDGiIsospin(); |
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202 | G4int iso2 = def2->GetPDGiIsospin(); |
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203 | |
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204 | G4int isoRes = resonance->GetPDGiIsospin(); |
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205 | |
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206 | if (isoRes < iso3) return 0.; |
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207 | if ((iso1*iso2) == 0) return 1.; |
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208 | |
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209 | cleb = clebsch.NormalizedClebschGordan(isoRes,iso3,iso1,iso2,iso31,iso32); |
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210 | |
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211 | // Special case: particle-antiparticle, charge-conjugated states have the same weight |
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212 | G4String type1 = def1->GetParticleType(); |
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213 | G4String type2 = def2->GetParticleType(); |
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214 | G4int anti = def1->GetPDGEncoding() * def2->GetPDGEncoding(); |
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215 | G4int strangeness = resonance->GetQuarkContent(3) + resonance->GetAntiQuarkContent(3); |
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216 | if ( ((type1 == "baryon" && type2 == "baryon") ||(type1 == "meson" && type2 == "meson")) && |
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217 | anti < 0 && strangeness == 0) |
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218 | { |
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219 | if (def1->GetPDGEncoding() != -(def2->GetPDGEncoding())) cleb = 0.5 * cleb; |
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220 | } |
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221 | |
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222 | return cleb; |
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223 | } |
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224 | |
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225 | |
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226 | |
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227 | |
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228 | |
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