[8] | 1 | #include "SigmaSgluonPairs.h" |
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| 2 | |
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| 3 | Sigma2qqbar2sgluonsgluonBar::Sigma2qqbar2sgluonsgluonBar(){ |
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| 4 | std::cout << "ERROR YOU SHOULD NOT HAVE LANDED HERE: Sigma2qqbar2sgluonsgluonBar::Sigma2qqbar2sgluonsgluonBar() " << std::endl; |
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| 5 | } |
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| 6 | Sigma2qqbar2sgluonsgluonBar::Sigma2qqbar2sgluonsgluonBar(int idResonanceIn) : Sigma2SgluonSgluonBase(idResonanceIn) { |
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| 7 | } |
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| 8 | Sigma2qqbar2sgluonsgluonBar::~Sigma2qqbar2sgluonsgluonBar(){ |
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| 9 | } |
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| 10 | // Initialize process. |
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| 11 | |
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| 12 | void Sigma2qqbar2sgluonsgluonBar::initProc() { |
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| 13 | |
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| 14 | // Set pointer to particle properties and decay table. |
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| 15 | m_particlePtr = particleDataPtr->particleDataEntryPtr(m_idsgluon); |
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| 16 | |
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| 17 | } |
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| 18 | |
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| 19 | //-------------------------------------------------------------------------- |
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| 20 | |
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| 21 | double Sigma2qqbar2sgluonsgluonBar::sigmaHat() { |
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| 22 | return m_sigma; |
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| 23 | } |
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| 24 | // Info on the subprocess. |
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| 25 | string Sigma2qqbar2sgluonsgluonBar::name() const { |
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| 26 | return "q qbar -> sgluon sgluonBar"; |
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| 27 | } |
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| 28 | int Sigma2qqbar2sgluonsgluonBar::code() const { |
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| 29 | return 10400; |
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| 30 | } |
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| 31 | string Sigma2qqbar2sgluonsgluonBar::inFlux() const { |
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| 32 | return "qqbarSame"; |
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| 33 | } |
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| 34 | int Sigma2qqbar2sgluonsgluonBar::resonanceA() const { |
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| 35 | return m_idsgluon; |
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| 36 | } |
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| 37 | |
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| 38 | int Sigma2qqbar2sgluonsgluonBar::id3Mass() const { |
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| 39 | return abs(m_idsgluon); |
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| 40 | } |
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| 41 | int Sigma2qqbar2sgluonsgluonBar::id4Mass() const { |
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| 42 | return abs(m_idsgluonBar); |
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| 43 | } |
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| 44 | |
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| 45 | // Evaluate sigmaHat(sHat); first step when inflavours unknown. |
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| 46 | |
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| 47 | void Sigma2qqbar2sgluonsgluonBar::sigmaKin() { |
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| 48 | |
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| 49 | // here we calculate the cross section independent of flavour |
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| 50 | m_sigma = 0.; |
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| 51 | |
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| 52 | // check that sHat > Q2=4*mSgluon**2 |
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| 53 | double sgluonMass = m_particlePtr->m0(); |
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| 54 | |
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| 55 | if ( sH <= 4.*sgluonMass*sgluonMass ) { |
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| 56 | return; |
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| 57 | } |
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| 58 | |
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| 59 | // convert tH to costheta |
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| 60 | double ctp = 2*tH-2*sgluonMass*sgluonMass+sH; |
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| 61 | ctp = ctp/(sqrtf(sH*(sH-4*sgluonMass*sgluonMass))); |
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| 62 | if (fabs(ctp)>1.e0 ) return; |
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| 63 | |
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| 64 | // Unit is GeV-2 |
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| 65 | m_sigma = dsigmadcostheta(ctp); |
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| 66 | |
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| 67 | // translate from dsigma/dcostheta to dsigma/dtheta: |
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| 68 | // dt = s/2 * sqrt(1-4m^2/s) * dcostheta |
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| 69 | double factor = convFactordsigmadcostheta2dsigmadt(sH,sgluonMass); |
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| 70 | m_sigma = m_sigma/factor; |
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| 71 | } |
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| 72 | |
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| 73 | double Sigma2qqbar2sgluonsgluonBar::dsigmadcostheta(double ctp) { |
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| 74 | |
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| 75 | double sgluonMass = m_particlePtr->m0(); |
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| 76 | double Q2 = sgluonMass*sgluonMass; |
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| 77 | double alphaS = couplingsPtr->alphaS(Q2); |
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| 78 | |
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| 79 | double beta=sqrtf(1.e0-4.e0*sgluonMass*sgluonMass/sH); |
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| 80 | |
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| 81 | double crossSection = (4.*M_PI*alphaS*alphaS)/(9.*sH)*beta*beta*beta; |
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| 82 | crossSection = crossSection*0.75e0*(1.e0-ctp*ctp); |
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| 83 | |
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| 84 | return crossSection; |
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| 85 | } |
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| 86 | |
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| 87 | // Select identity, colour and anticolour. |
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| 88 | |
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| 89 | void Sigma2qqbar2sgluonsgluonBar::setIdColAcol() { |
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| 90 | |
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| 91 | // Flavours trivial. |
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| 92 | setId( id1, id2, m_idsgluon, m_idsgluonBar); |
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| 93 | |
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| 94 | // Colour flow topologies. Swap when antiquarks. |
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| 95 | setColAcol( 1, 0, 0, 2, 1, 3, 3, 2); |
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| 96 | if (id1 < 0) swapColAcol(); |
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| 97 | |
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| 98 | } |
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| 99 | |
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| 100 | Sigma2gg2sgluonsgluonBar::Sigma2gg2sgluonsgluonBar(){ |
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| 101 | std::cout << "ERROR YOU SHOULD NOT HAVE LANDED HERE: Sigma2gg2sgluonsgluonBar::Sigma2gg2sgluonsgluonBar() " << std::endl; |
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| 102 | } |
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| 103 | Sigma2gg2sgluonsgluonBar::Sigma2gg2sgluonsgluonBar(int idResonanceIn) : Sigma2SgluonSgluonBase(idResonanceIn) { |
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| 104 | } |
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| 105 | Sigma2gg2sgluonsgluonBar::~Sigma2gg2sgluonsgluonBar(){ |
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| 106 | } |
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| 107 | // Here we have gg -> sgluon sgluonBar |
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| 108 | double Sigma2gg2sgluonsgluonBar::sigmaHat() { |
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| 109 | return m_sigma; |
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| 110 | } |
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| 111 | string Sigma2gg2sgluonsgluonBar::name() const { |
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| 112 | return "g g -> sgluon sgluonBar"; |
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| 113 | } |
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[9] | 114 | int Sigma2gg2sgluonsgluonBar::code() const { |
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[8] | 115 | return 10401; |
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| 116 | } |
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| 117 | string Sigma2gg2sgluonsgluonBar::inFlux() const { |
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| 118 | return "gg"; |
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| 119 | } |
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| 120 | int Sigma2gg2sgluonsgluonBar::resonanceA() const { |
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| 121 | return m_idsgluon; |
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| 122 | } |
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| 123 | int Sigma2gg2sgluonsgluonBar::id3Mass() const { |
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| 124 | return abs(m_idsgluon); |
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| 125 | } |
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| 126 | int Sigma2gg2sgluonsgluonBar::id4Mass() const { |
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| 127 | return abs(m_idsgluonBar); |
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| 128 | } |
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| 129 | |
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| 130 | |
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| 131 | // Initialize process. |
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| 132 | |
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| 133 | void Sigma2gg2sgluonsgluonBar::initProc() { |
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| 134 | |
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| 135 | // Set pointer to particle properties and decay table. |
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| 136 | m_particlePtr = particleDataPtr->particleDataEntryPtr(m_idsgluon); |
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| 137 | |
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| 138 | } |
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| 139 | |
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| 140 | //-------------------------------------------------------------------------- |
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| 141 | |
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| 142 | // Evaluate sigmaHat(sHat); first step when inflavours unknown. |
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| 143 | |
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| 144 | void Sigma2gg2sgluonsgluonBar::sigmaKin() { |
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| 145 | |
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| 146 | // here we calculate the cross section independent of flavour |
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| 147 | m_sigma = 0.; |
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| 148 | |
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| 149 | // check that sHat > Q2=4*mSgluon**2 |
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| 150 | double sgluonMass = m_particlePtr->m0(); |
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| 151 | |
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| 152 | if ( sH <= 4.*sgluonMass*sgluonMass ) { |
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| 153 | return; |
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| 154 | } |
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| 155 | |
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| 156 | double ctp = 2*tH-2*sgluonMass*sgluonMass+sH; |
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| 157 | ctp = ctp/(sqrtf(sH*(sH-4*sgluonMass*sgluonMass))); |
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| 158 | if (fabs(ctp)>1.e0 ) return; |
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| 159 | |
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| 160 | // unit is GeV-2 |
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| 161 | m_sigma = dsigmadcostheta(ctp); |
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| 162 | |
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| 163 | // translate from dsigma/dcostheta to dsigma/dtheta: |
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| 164 | // dt = s/2 * sqrt(1-4m^2/s) * dcostheta |
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| 165 | double factor = convFactordsigmadcostheta2dsigmadt(sH,sgluonMass); |
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| 166 | m_sigma = m_sigma/factor; |
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| 167 | |
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| 168 | } |
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| 169 | |
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| 170 | //-------------------------------------------------------------------------- |
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| 171 | |
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| 172 | double Sigma2gg2sgluonsgluonBar::dsigmadcostheta(double ctp) { |
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| 173 | |
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| 174 | // process gg -> sigma sigma differential cross section |
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| 175 | |
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| 176 | double sgluonMass = m_particlePtr->m0(); |
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| 177 | double Q2 = sgluonMass*sgluonMass; |
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| 178 | |
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| 179 | double alphaS = couplingsPtr->alphaS(Q2); |
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| 180 | |
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| 181 | double beta= sqrtf(1.e0-4.e0*sgluonMass*sgluonMass/sH); |
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| 182 | double beta2 = beta*beta; |
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| 183 | |
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| 184 | double crossSection = M_PI*(alphaS*alphaS)*beta/(6.*sH)*(9./8.)* |
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| 185 | (27.-17.*beta2 - 6.*(1.e0-beta2)*(3.e0+beta2) |
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| 186 | /(2.e0*beta)*log((1.e0+beta)/(1.e0-beta))); |
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| 187 | |
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| 188 | double ctp2 = ctp*ctp; |
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| 189 | double stp4 = (1.e0-ctp2)*(1.e0-ctp2); |
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| 190 | |
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| 191 | double cr = 1.5e0*((1.e0-beta2)*(1.e0-beta2) + beta2*beta2*stp4)/ |
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[9] | 192 | ((1.e0-beta2*ctp2)*(1.e0-beta2*ctp2)) * (3.e0+beta2*ctp2)/ |
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[8] | 193 | ( 27.e0-17.e0*beta2-6.e0*(1.e0-beta2)*(3.e0+beta2)/ |
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| 194 | (2.e0*beta)*log((1.e0+beta)/(1.e0-beta))); |
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| 195 | |
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| 196 | crossSection = crossSection*cr; |
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| 197 | |
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| 198 | return crossSection; |
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| 199 | } |
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| 200 | |
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| 201 | // Select identity, colour and anticolour. |
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| 202 | |
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| 203 | void Sigma2gg2sgluonsgluonBar::setIdColAcol() { |
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| 204 | |
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| 205 | // Flavours trivial. |
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| 206 | setId( id1, id2, m_idsgluon, m_idsgluonBar); |
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| 207 | |
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| 208 | // Colour flow topologies of 4 colour octets |
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| 209 | setColAcol( 1, 2, 2, 3, 1, 4, 4, 3); |
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| 210 | |
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| 211 | } |
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| 212 | |
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