Gabriele Cosmo
274 lines
9.3 KiB
C++
274 lines
9.3 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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//
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// $Id$
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//
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// -----------------------------------------------------------------------------
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// GEANT 4 class implementation file
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//
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// History:
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// Gunter Folger, August/September 2001
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// Create class; algorithm previously in G4VLongitudinalStringDecay.
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// -----------------------------------------------------------------------------
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#include "G4HadronBuilder.hh"
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#include "G4SystemOfUnits.hh"
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#include "Randomize.hh"
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#include "G4HadronicException.hh"
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#include "G4ParticleTable.hh"
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G4HadronBuilder::G4HadronBuilder(G4double mesonMix, G4double barionMix,
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std::vector<double> scalarMesonMix,
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std::vector<double> vectorMesonMix)
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{
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mesonSpinMix=mesonMix;
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barionSpinMix=barionMix;
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scalarMesonMixings=scalarMesonMix;
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vectorMesonMixings=vectorMesonMix;
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}
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G4ParticleDefinition * G4HadronBuilder::Build(G4ParticleDefinition * black, G4ParticleDefinition * white)
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{
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if (black->GetParticleSubType()== "di_quark" || white->GetParticleSubType()== "di_quark" ) {
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// Barion
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Spin spin = (G4UniformRand() < barionSpinMix) ? SpinHalf : SpinThreeHalf;
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return Barion(black,white,spin);
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} else {
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// Meson
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Spin spin = (G4UniformRand() < mesonSpinMix) ? SpinZero : SpinOne;
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return Meson(black,white,spin);
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}
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}
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//-------------------------------------------------------------------------
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G4ParticleDefinition * G4HadronBuilder::BuildLowSpin(G4ParticleDefinition * black, G4ParticleDefinition * white)
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{
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if ( black->GetParticleSubType()== "quark" && white->GetParticleSubType()== "quark" ) {
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return Meson(black,white, SpinZero);
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} else {
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// will return a SpinThreeHalf Barion if all quarks the same
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return Barion(black,white, SpinHalf);
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}
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}
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//-------------------------------------------------------------------------
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G4ParticleDefinition * G4HadronBuilder::BuildHighSpin(G4ParticleDefinition * black, G4ParticleDefinition * white)
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{
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if ( black->GetParticleSubType()== "quark" && white->GetParticleSubType()== "quark" ) {
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return Meson(black,white, SpinOne);
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} else {
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return Barion(black,white,SpinThreeHalf);
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}
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}
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//-------------------------------------------------------------------------
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G4ParticleDefinition * G4HadronBuilder::Meson(G4ParticleDefinition * black,
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G4ParticleDefinition * white, Spin theSpin)
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{
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#ifdef G4VERBOSE
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// Verify Input Charge
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G4double charge = black->GetPDGCharge()
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+ white->GetPDGCharge();
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if (std::abs(charge) > 2 || std::abs(3.*charge - 3*G4int(charge*1.001)) > perCent ) // 1.001 to avoid int(.9999) -> 0
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{
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G4cerr << " G4HadronBuilder::Build()" << G4endl;
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G4cerr << " Invalid total charge found for on input: "
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<< charge<< G4endl;
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G4cerr << " PGDcode input quark1/quark2 : " <<
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black->GetPDGEncoding() << " / "<<
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white->GetPDGEncoding() << G4endl;
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G4cerr << G4endl;
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}
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#endif
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G4int id1= black->GetPDGEncoding();
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G4int id2= white->GetPDGEncoding();
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// G4int ifl1= std::max(std::abs(id1), std::abs(id2));
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if ( std::abs(id1) < std::abs(id2) )
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{
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G4int xchg = id1;
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id1 = id2;
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id2 = xchg;
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}
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if (std::abs(id1) > 3 )
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throw G4HadronicException(__FILE__, __LINE__, "G4HadronBuilder::Meson : Illegal Quark content as input");
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G4int PDGEncoding=0;
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if (id1 + id2 == 0) {
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G4double rmix = G4UniformRand();
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G4int imix = 2*std::abs(id1) - 1;
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if(theSpin == SpinZero) {
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PDGEncoding = 110*(1 + (G4int)(rmix + scalarMesonMixings[imix - 1])
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+ (G4int)(rmix + scalarMesonMixings[imix])
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) + theSpin;
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} else {
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PDGEncoding = 110*(1 + (G4int)(rmix + vectorMesonMixings[imix - 1])
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+ (G4int)(rmix + vectorMesonMixings[imix])
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) + theSpin;
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}
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} else {
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PDGEncoding = 100 * std::abs(id1) + 10 * std::abs(id2) + theSpin;
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G4bool IsUp = (std::abs(id1)&1) == 0; // quark 1 up type quark (u or c)
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G4bool IsAnti = id1 < 0; // quark 1 is antiquark?
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if( (IsUp && IsAnti ) || (!IsUp && !IsAnti ) )
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PDGEncoding = - PDGEncoding;
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}
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G4ParticleDefinition * MesonDef=
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G4ParticleTable::GetParticleTable()->FindParticle(PDGEncoding);
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#ifdef G4VERBOSE
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if (MesonDef == 0 ) {
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G4cerr << " G4HadronBuilder - Warning: No particle for PDGcode= "
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<< PDGEncoding << G4endl;
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} else if ( ( black->GetPDGCharge() + white->GetPDGCharge()
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- MesonDef->GetPDGCharge() ) > perCent ) {
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G4cerr << " G4HadronBuilder - Warning: Incorrect Charge : "
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<< " Quark1/2 = "
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<< black->GetParticleName() << " / "
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<< white->GetParticleName()
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<< " resulting Hadron " << MesonDef->GetParticleName()
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<< G4endl;
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}
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#endif
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return MesonDef;
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}
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G4ParticleDefinition * G4HadronBuilder::Barion(G4ParticleDefinition * black,
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G4ParticleDefinition * white,Spin theSpin)
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{
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#ifdef G4VERBOSE
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// Verify Input Charge
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G4double charge = black->GetPDGCharge()
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+ white->GetPDGCharge();
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if (std::abs(charge) > 2 || std::abs(3.*charge - 3*G4int(charge*1.001)) > perCent )
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{
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G4cerr << " G4HadronBuilder::Build()" << G4endl;
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G4cerr << " Invalid total charge found for on input: "
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<< charge<< G4endl;
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G4cerr << " PGDcode input quark1/quark2 : " <<
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black->GetPDGEncoding() << " / "<<
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white->GetPDGEncoding() << G4endl;
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G4cerr << G4endl;
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}
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#endif
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G4int id1= black->GetPDGEncoding();
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G4int id2= white->GetPDGEncoding();
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if ( std::abs(id1) < std::abs(id2) )
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{
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G4int xchg = id1;
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id1 = id2;
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id2 = xchg;
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}
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if (std::abs(id1) < 1000 || std::abs(id2) > 3 )
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throw G4HadronicException(__FILE__, __LINE__, "G4HadronBuilder::Barion: Illegal quark content as input");
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G4int ifl1= std::abs(id1)/1000;
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G4int ifl2 = (std::abs(id1) - ifl1 * 1000)/100;
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G4int diquarkSpin = std::abs(id1)%10;
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G4int ifl3 = id2;
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if (id1 < 0)
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{
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ifl1 = - ifl1;
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ifl2 = - ifl2;
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}
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//... Construct barion, distinguish Lambda and Sigma barions.
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G4int kfla = std::abs(ifl1);
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G4int kflb = std::abs(ifl2);
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G4int kflc = std::abs(ifl3);
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G4int kfld = std::max(kfla,kflb);
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kfld = std::max(kfld,kflc);
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G4int kflf = std::min(kfla,kflb);
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kflf = std::min(kflf,kflc);
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G4int kfle = kfla + kflb + kflc - kfld - kflf;
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//... barion with content uuu or ddd or sss has always spin = 3/2
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theSpin = (kfla == kflb && kflb == kflc)? SpinThreeHalf : theSpin;
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G4int kfll = 0;
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if(theSpin == SpinHalf && kfld > kfle && kfle > kflf) {
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// Spin J=1/2 and all three quarks different
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// Two states exist: (uds -> lambda or sigma0)
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// - lambda: s(ud)0 s : 3122; ie. reverse the two lighter quarks
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// - sigma0: s(ud)1 s : 3212
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if(diquarkSpin == 1 ) {
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if ( kfla == kfld) { // heaviest quark in diquark
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kfll = 1;
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} else {
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kfll = (G4int)(0.25 + G4UniformRand());
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}
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}
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if(diquarkSpin == 3 && kfla != kfld)
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kfll = (G4int)(0.75 + G4UniformRand());
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}
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G4int PDGEncoding;
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if (kfll == 1)
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PDGEncoding = 1000 * kfld + 100 * kflf + 10 * kfle + theSpin;
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else
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PDGEncoding = 1000 * kfld + 100 * kfle + 10 * kflf + theSpin;
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if (id1 < 0)
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PDGEncoding = -PDGEncoding;
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G4ParticleDefinition * BarionDef=
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G4ParticleTable::GetParticleTable()->FindParticle(PDGEncoding);
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#ifdef G4VERBOSE
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if (BarionDef == 0 ) {
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G4cerr << " G4HadronBuilder - Warning: No particle for PDGcode= "
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<< PDGEncoding << G4endl;
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} else if ( ( black->GetPDGCharge() + white->GetPDGCharge()
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- BarionDef->GetPDGCharge() ) > perCent ) {
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G4cerr << " G4HadronBuilder - Warning: Incorrect Charge : "
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<< " DiQuark/Quark = "
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<< black->GetParticleName() << " / "
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<< white->GetParticleName()
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<< " resulting Hadron " << BarionDef->GetParticleName()
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<< G4endl;
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}
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#endif
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return BarionDef;
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}
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