[819] | 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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