1 | // SigmaProcess.h is a part of the PYTHIA event generator. |
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2 | // Copyright (C) 2012 Torbjorn Sjostrand. |
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3 | // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details. |
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4 | // Please respect the MCnet Guidelines, see GUIDELINES for details. |
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5 | |
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6 | // Header file for hard-process differential cross sections. |
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7 | // SigmaProcess: base class for cross sections. |
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8 | // Sigma0Process: base class for unresolved processes, derived from above. |
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9 | // Sigma1Process: base class for 2 -> 1 processes, derived from above. |
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10 | // Sigma2Process: base class for 2 -> 2 processes, derived from above. |
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11 | // Sigma3Process: base class for 2 -> 3 processes, derived from above. |
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12 | // SigmaLHAProcess: wrapper class for Les Houches Accord external input. |
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13 | // Actual physics processes are found in separate files: |
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14 | // SigmaQCD for QCD processes; |
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15 | // SigmaEW for electroweak processes (including photon production); |
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16 | // SigmaOnia for charmonium and bottomonium processes; |
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17 | // SigmaHiggs for Higgs processes; |
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18 | // SigmaSUSY for supersymmetric production; |
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19 | // SigmaLeftRightSym for processes in left-right-symmetric scenarios; |
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20 | // SigmaLeptoquark for leptoquark production. |
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21 | // SigmaExtraDim for processes in scenarios for extra dimensions; |
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22 | // SigmaGeneric for generic scalar/fermion/vector pair production. |
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23 | |
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24 | #ifndef Pythia8_SigmaProcess_H |
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25 | #define Pythia8_SigmaProcess_H |
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26 | |
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27 | #include "Basics.h" |
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28 | #include "BeamParticle.h" |
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29 | #include "Event.h" |
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30 | #include "Info.h" |
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31 | #include "LesHouches.h" |
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32 | #include "ParticleData.h" |
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33 | #include "PartonDistributions.h" |
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34 | #include "PythiaComplex.h" |
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35 | #include "PythiaStdlib.h" |
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36 | #include "ResonanceWidths.h" |
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37 | #include "Settings.h" |
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38 | #include "SigmaTotal.h" |
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39 | #include "StandardModel.h" |
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40 | #include "SusyLesHouches.h" |
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41 | |
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42 | namespace Pythia8 { |
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43 | |
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44 | //========================================================================== |
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45 | |
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46 | // InBeam is a simple helper class for partons and their flux in a beam. |
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47 | |
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48 | class InBeam { |
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49 | |
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50 | public: |
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51 | |
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52 | // Constructor. |
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53 | InBeam( int idIn = 0) : id(idIn), pdf(0.) {} |
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54 | |
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55 | // Values. |
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56 | int id; |
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57 | double pdf; |
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58 | |
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59 | }; |
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60 | |
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61 | //========================================================================== |
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62 | |
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63 | // InPair is a simple helper class for colliding parton pairs and their flux. |
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64 | |
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65 | class InPair { |
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66 | |
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67 | public: |
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68 | |
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69 | // Constructor. |
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70 | InPair( int idAIn = 0, int idBIn = 0) : idA(idAIn), idB(idBIn), |
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71 | pdfA(0.), pdfB(0.), pdfSigma(0.) {} |
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72 | |
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73 | // Values. |
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74 | int idA, idB; |
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75 | double pdfA, pdfB, pdfSigma; |
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76 | |
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77 | }; |
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78 | |
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79 | //========================================================================== |
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80 | |
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81 | // SigmaProcess is the base class for cross section calculations. |
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82 | |
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83 | class SigmaProcess { |
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84 | |
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85 | public: |
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86 | |
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87 | // Destructor. |
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88 | virtual ~SigmaProcess() {} |
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89 | |
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90 | // Perform simple initialization and store pointers. |
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91 | void init(Info* infoPtrIn, Settings* settingsPtrIn, |
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92 | ParticleData* particleDataPtrIn, Rndm* rndmPtrIn, |
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93 | BeamParticle* beamAPtrIn, BeamParticle* beamBPtrIn, Couplings* couplings, |
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94 | SigmaTotal* sigmaTotPtrIn = 0, SusyLesHouches* slhaPtr = 0); |
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95 | |
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96 | // Store or replace Les Houches pointer. |
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97 | void setLHAPtr( LHAup* lhaUpPtrIn) {lhaUpPtr = lhaUpPtrIn;} |
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98 | |
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99 | // Initialize process. Only used for some processes. |
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100 | virtual void initProc() {} |
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101 | |
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102 | // Set up allowed flux of incoming partons. Default is no flux. |
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103 | virtual bool initFlux(); |
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104 | |
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105 | // Input and complement kinematics for resolved 2 -> 1 process. |
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106 | // Usage: set1Kin( x1in, x2in, sHin). |
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107 | virtual void set1Kin( double , double , double ) {} |
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108 | |
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109 | // Input and complement kinematics for resolved 2 -> 2 process. |
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110 | // Usage: set2Kin( x1in, x2in, sHin, tHin, m3in, m4in, runBW3in, runBW4in). |
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111 | virtual void set2Kin( double , double , double , double , double , |
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112 | double, double, double ) {} |
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113 | |
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114 | // Ditto, but for Multiparton Interactions applications, so different input. |
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115 | // Usage: set2KinMPI( x1in, x2in, sHin, tHin, uHin, |
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116 | // alpSin, alpEMin, needMasses, m3in, m4in) |
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117 | virtual void set2KinMPI( double , double , double , double , |
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118 | double , double , double , bool , double , double ) {} |
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119 | |
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120 | // Input and complement kinematics for resolved 2 -> 3 process. |
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121 | // Usage: set3Kin( x1in, x2in, sHin, p3prel, p4prel, p5prel, |
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122 | // m3in, m4in, m5in, runBW3in, runBW4in, runBW5in); |
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123 | virtual void set3Kin( double , double , double , Vec4 , Vec4 , Vec4 , |
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124 | double , double , double , double , double , double ) {} |
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125 | |
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126 | // Calculate flavour-independent parts of cross section. |
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127 | virtual void sigmaKin() {} |
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128 | |
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129 | // Evaluate sigma for unresolved, sigmaHat(sHat) for 2 -> 1 processes, |
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130 | // d(sigmaHat)/d(tHat) for (resolved) 2 -> 2 processes, and |M|^2 for |
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131 | // 2 -> 3 processes. Answer in "native" units, either mb or GeV^-2. |
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132 | virtual double sigmaHat() {return 0.;} |
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133 | |
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134 | // Wrapper to sigmaHat, to (a) store current incoming flavours and |
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135 | // (b) convert from GeV^-2 to mb where required. |
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136 | // For 2 -> 1/2 also (c) convert from from |M|^2 to d(sigmaHat)/d(tHat). |
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137 | virtual double sigmaHatWrap(int id1in = 0, int id2in = 0) { |
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138 | id1 = id1in; id2 = id2in; |
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139 | return ( convert2mb() ? CONVERT2MB * sigmaHat() : sigmaHat() ); } |
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140 | |
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141 | // Convolute above with parton flux and K factor. Sum over open channels. |
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142 | virtual double sigmaPDF(); |
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143 | |
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144 | // Select incoming parton channel and extract parton densities (resolved). |
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145 | void pickInState(int id1in = 0, int id2in = 0); |
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146 | |
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147 | // Select flavour, colour and anticolour. |
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148 | virtual void setIdColAcol() {} |
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149 | |
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150 | // Perform kinematics for a Multiparton Interaction, in its rest frame. |
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151 | virtual bool final2KinMPI( int = 0, int = 0, Vec4 = 0., Vec4 = 0., |
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152 | double = 0., double = 0.) {return true;} |
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153 | |
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154 | // Evaluate weight for simultaneous flavours (only gamma*/Z0 gamma*/Z0). |
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155 | // Usage: weightDecayFlav( process). |
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156 | virtual double weightDecayFlav( Event&) {return 1.;} |
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157 | |
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158 | // Evaluate weight for decay angular configuration. |
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159 | // Usage: weightDecay( process, iResBeg, iResEnd), where |
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160 | // iResBeg <= i < iResEnd is range of sister partons to test decays of. |
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161 | virtual double weightDecay( Event&, int, int) {return 1.;} |
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162 | |
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163 | // Set scale, when that is missing for an external LHA process. |
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164 | virtual void setScale() {} |
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165 | |
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166 | // Process name and code, and the number of final-state particles. |
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167 | virtual string name() const {return "unnamed process";} |
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168 | virtual int code() const {return 0;} |
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169 | virtual int nFinal() const {return 2;} |
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170 | |
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171 | // Need to know which incoming partons to set up interaction for. |
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172 | virtual string inFlux() const {return "unknown";} |
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173 | |
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174 | // Need to know whether to convert cross section answer from GeV^-2 to mb. |
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175 | virtual bool convert2mb() const {return true;} |
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176 | |
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177 | // For 2 -> 2 process optional conversion from |M|^2 to d(sigmaHat)/d(tHat). |
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178 | virtual bool convertM2() const {return false;} |
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179 | |
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180 | // Special treatment needed for Les Houches processes. |
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181 | virtual bool isLHA() const {return false;} |
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182 | |
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183 | // Special treatment needed for elastic and diffractive processes. |
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184 | virtual bool isMinBias() const {return false;} |
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185 | virtual bool isResolved() const {return true;} |
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186 | virtual bool isDiffA() const {return false;} |
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187 | virtual bool isDiffB() const {return false;} |
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188 | virtual bool isDiffC() const {return false;} |
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189 | |
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190 | // Special treatment needed for SUSY processes. |
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191 | virtual bool isSUSY() const {return false;} |
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192 | |
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193 | // Special treatment needed if negative cross sections allowed. |
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194 | virtual bool allowNegativeSigma() const {return false;} |
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195 | |
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196 | // Flavours in 2 -> 2/3 processes where masses needed from beginning. |
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197 | // (For a light quark masses will be used in the final kinematics, |
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198 | // but not at the matrix-element level. For a gluon no masses at all.) |
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199 | virtual int id3Mass() const {return 0;} |
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200 | virtual int id4Mass() const {return 0;} |
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201 | virtual int id5Mass() const {return 0;} |
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202 | |
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203 | // Special treatment needed if process contains an s-channel resonance. |
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204 | virtual int resonanceA() const {return 0;} |
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205 | virtual int resonanceB() const {return 0;} |
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206 | |
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207 | // 2 -> 2 and 2 -> 3 processes only through s-channel exchange. |
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208 | virtual bool isSChannel() const {return false;} |
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209 | |
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210 | // NOAM: Insert an intermediate resonance in 2 -> 1 -> 2 (or 3) listings. |
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211 | virtual int idSChannel() const {return 0;} |
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212 | |
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213 | // QCD 2 -> 3 processes need special phase space selection machinery. |
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214 | virtual bool isQCD3body() const {return false;} |
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215 | |
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216 | // Special treatment in 2 -> 3 with two massive propagators. |
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217 | virtual int idTchan1() const {return 0;} |
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218 | virtual int idTchan2() const {return 0;} |
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219 | virtual double tChanFracPow1() const {return 0.3;} |
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220 | virtual double tChanFracPow2() const {return 0.3;} |
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221 | virtual bool useMirrorWeight() const {return false;} |
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222 | |
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223 | // Special process-specific gamma*/Z0 choice if >=0 (e.g. f fbar -> H0 Z0). |
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224 | virtual int gmZmode() const {return -1;} |
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225 | |
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226 | // Tell whether tHat and uHat are swapped (= same as swap 3 and 4). |
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227 | bool swappedTU() const {return swapTU;} |
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228 | |
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229 | // Give back particle properties: flavours, colours, masses, or all. |
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230 | int id(int i) const {return idSave[i];} |
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231 | int col(int i) const {return colSave[i];} |
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232 | int acol(int i) const {return acolSave[i];} |
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233 | double m(int i) const {return mSave[i];} |
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234 | Particle getParton(int i) const {return parton[i];} |
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235 | |
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236 | // Give back couplings and parton densities. Not all known for minbias. |
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237 | double Q2Ren() const {return Q2RenSave;} |
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238 | double alphaEMRen() const {return alpEM;} |
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239 | double alphaSRen() const {return alpS;} |
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240 | double Q2Fac() const {return Q2FacSave;} |
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241 | double pdf1() const {return pdf1Save;} |
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242 | double pdf2() const {return pdf2Save;} |
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243 | |
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244 | // Give back angles; relevant only for multipe-interactions processes. |
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245 | double thetaMPI() const {return atan2( sinTheta, cosTheta);} |
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246 | double phiMPI() const {return phi;} |
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247 | double sHBetaMPI() const {return sHBeta;} |
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248 | double pT2MPI() const {return pT2Mass;} |
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249 | double pTMPIFin() const {return pTFin;} |
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250 | |
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251 | // Save and load kinematics for trial interactions |
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252 | void saveKin() { |
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253 | for (int i = 0; i < 6; i++) { partonT[i] = parton[i]; |
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254 | mSaveT[i] = mSave[i]; } |
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255 | pTFinT = pTFin; phiT = phi; cosThetaT = cosTheta; sinThetaT = sinTheta; } |
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256 | void loadKin() { |
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257 | for (int i = 0; i < 6; i++) { parton[i] = partonT[i]; |
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258 | mSave[i] = mSaveT[i]; } |
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259 | pTFin = pTFinT; cosTheta = cosThetaT; sinTheta = sinThetaT; phi = phiT; |
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260 | } |
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261 | void swapKin() { |
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262 | for (int i = 0; i < 6; i++) { swap(parton[i], partonT[i]); |
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263 | swap(mSave[i], mSaveT[i]); } |
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264 | swap(pTFin, pTFinT); swap(cosTheta, cosThetaT); |
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265 | swap(sinTheta, sinThetaT); swap(phi, phiT); } |
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266 | |
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267 | protected: |
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268 | |
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269 | // Constructor. |
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270 | SigmaProcess() : infoPtr(0), settingsPtr(0), particleDataPtr(0), |
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271 | rndmPtr(0), beamAPtr(0), beamBPtr(0), couplingsPtr(0), sigmaTotPtr(0), |
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272 | slhaPtr(0), lhaUpPtr(0) {for (int i = 0; i < 6; ++i) mSave[i] = 0.;} |
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273 | |
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274 | // Constants: could only be changed in the code itself. |
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275 | static const double CONVERT2MB, MASSMARGIN, COMPRELERR; |
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276 | static const int NCOMPSTEP; |
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277 | |
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278 | // Pointer to various information on the generation. |
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279 | Info* infoPtr; |
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280 | |
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281 | // Pointer to the settings database. |
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282 | Settings* settingsPtr; |
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283 | |
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284 | // Pointer to the particle data table. |
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285 | ParticleData* particleDataPtr; |
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286 | |
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287 | // Pointer to the random number generator. |
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288 | Rndm* rndmPtr; |
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289 | |
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290 | // Pointers to incoming beams. |
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291 | BeamParticle* beamAPtr; |
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292 | BeamParticle* beamBPtr; |
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293 | |
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294 | // Pointer to Standard Model couplings, including alphaS and alphaEM. |
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295 | Couplings* couplingsPtr; |
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296 | |
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297 | // Pointer to the total/elastic/diffractive cross section object. |
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298 | SigmaTotal* sigmaTotPtr; |
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299 | |
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300 | // Pointer to the SLHA object. |
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301 | SusyLesHouches* slhaPtr; |
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302 | |
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303 | // Pointer to LHAup for generating external events. |
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304 | LHAup* lhaUpPtr; |
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305 | |
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306 | // Initialization data, normally only set once. |
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307 | int nQuarkIn, renormScale1, renormScale2, renormScale3, renormScale3VV, |
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308 | factorScale1, factorScale2, factorScale3, factorScale3VV; |
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309 | double Kfactor, mcME, mbME, mmuME, mtauME, renormMultFac, renormFixScale, |
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310 | factorMultFac, factorFixScale; |
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311 | |
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312 | // CP violation parameters for Higgs sector, normally only set once. |
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313 | int higgsH1parity, higgsH2parity, higgsA3parity; |
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314 | double higgsH1eta, higgsH2eta, higgsA3eta; |
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315 | |
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316 | // Information on incoming beams. |
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317 | int idA, idB; |
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318 | double mA, mB; |
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319 | bool isLeptonA, isLeptonB, hasLeptonBeams; |
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320 | |
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321 | // Partons in beams, with PDF's. |
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322 | vector<InBeam> inBeamA; |
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323 | vector<InBeam> inBeamB; |
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324 | void addBeamA(int idIn) {inBeamA.push_back(InBeam(idIn));} |
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325 | void addBeamB(int idIn) {inBeamB.push_back(InBeam(idIn));} |
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326 | int sizeBeamA() const {return inBeamA.size();} |
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327 | int sizeBeamB() const {return inBeamB.size();} |
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328 | |
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329 | // Allowed colliding parton pairs, with pdf's. |
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330 | vector<InPair> inPair; |
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331 | void addPair(int idAIn, int idBIn) { |
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332 | inPair.push_back(InPair(idAIn, idBIn));} |
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333 | int sizePair() const {return inPair.size();} |
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334 | |
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335 | // Store common subprocess kinematics quantities. |
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336 | double mH, sH, sH2; |
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337 | |
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338 | // Store Q2 renormalization and factorization scales, and related values. |
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339 | double Q2RenSave, alpEM, alpS, Q2FacSave, x1Save, x2Save, pdf1Save, |
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340 | pdf2Save, sigmaSumSave; |
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341 | |
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342 | // Store flavour, colour, anticolour, mass, angles and the whole particle. |
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343 | int id1, id2, id3, id4, id5; |
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344 | int idSave[6], colSave[6], acolSave[6]; |
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345 | double mSave[6], cosTheta, sinTheta, phi, sHMass, sHBeta, pT2Mass, pTFin; |
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346 | Particle parton[6]; |
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347 | |
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348 | // Minimal set of saved kinematics for trial interactions when |
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349 | // using the x-dependent matter profile of multiparton interactions. |
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350 | Particle partonT[6]; |
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351 | double mSaveT[6], pTFinT, cosThetaT, sinThetaT, phiT; |
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352 | |
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353 | // Calculate and store all modified masses and four-vectors |
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354 | // intended for matrix elements. Return false if failed. |
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355 | virtual bool setupForME() {return true;} |
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356 | bool setupForMEin(); |
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357 | double mME[5]; |
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358 | Vec4 pME[5]; |
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359 | |
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360 | // Store whether tHat and uHat are swapped (= same as swap 3 and 4). |
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361 | bool swapTU; |
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362 | |
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363 | // Set flavour, colour and anticolour. |
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364 | void setId( int id1in = 0, int id2in = 0, int id3in = 0, int id4in = 0, |
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365 | int id5in = 0) {idSave[1] = id1in; idSave[2] = id2in; idSave[3] = id3in; |
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366 | idSave[4] = id4in; idSave[5] = id5in;} |
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367 | void setColAcol( int col1 = 0, int acol1 = 0, |
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368 | int col2 = 0, int acol2 = 0, int col3 = 0, int acol3 = 0, |
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369 | int col4 = 0, int acol4 = 0, int col5 = 0, int acol5 = 0) { |
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370 | colSave[1] = col1; acolSave[1] = acol1; colSave[2] = col2; |
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371 | acolSave[2] = acol2; colSave[3] = col3; acolSave[3] = acol3; |
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372 | colSave[4] = col4; acolSave[4] = acol4; colSave[5] = col5; |
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373 | acolSave[5] = acol5; } |
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374 | void swapColAcol() { swap(colSave[1], acolSave[1]); |
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375 | swap(colSave[2], acolSave[2]); swap(colSave[3], acolSave[3]); |
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376 | swap(colSave[4], acolSave[4]); swap(colSave[5], acolSave[5]);} |
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377 | void swapCol1234() { swap(colSave[1], colSave[2]); |
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378 | swap(colSave[3], colSave[4]); swap(acolSave[1], acolSave[2]); |
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379 | swap(acolSave[3], acolSave[4]);} |
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380 | void swapCol12() { swap(colSave[1], colSave[2]); |
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381 | swap(acolSave[1], acolSave[2]);} |
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382 | void swapCol34() { swap(colSave[3], colSave[4]); |
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383 | swap(acolSave[3], acolSave[4]);} |
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384 | |
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385 | // Common code for top and Higgs secondary decay angular weights. |
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386 | double weightTopDecay( Event& process, int iResBeg, int iResEnd); |
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387 | double weightHiggsDecay( Event& process, int iResBeg, int iResEnd); |
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388 | |
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389 | }; |
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390 | |
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391 | //========================================================================== |
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392 | |
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393 | // Sigma0Process is the base class for unresolved and minimum-bias processes. |
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394 | // It is derived from SigmaProcess. |
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395 | |
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396 | class Sigma0Process : public SigmaProcess { |
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397 | |
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398 | public: |
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399 | |
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400 | // Destructor. |
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401 | virtual ~Sigma0Process() {} |
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402 | |
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403 | // Number of final-state particles. |
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404 | virtual int nFinal() const {return 2;}; |
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405 | |
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406 | // No partonic flux to be set up. |
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407 | virtual bool initFlux() {return true;} |
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408 | |
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409 | // Evaluate sigma for unresolved processes. |
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410 | virtual double sigmaHat() {return 0.;} |
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411 | |
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412 | // Since no PDF's there is no difference from above. |
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413 | virtual double sigmaPDF() {return sigmaHat();} |
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414 | |
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415 | // Answer for these processes already in mb, so do not convert. |
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416 | virtual bool convert2mb() const {return false;} |
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417 | |
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418 | protected: |
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419 | |
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420 | // Constructor. |
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421 | Sigma0Process() {} |
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422 | |
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423 | }; |
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424 | |
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425 | //========================================================================== |
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426 | |
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427 | // Sigma1Process is the base class for 2 -> 1 processes. |
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428 | // It is derived from SigmaProcess. |
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429 | |
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430 | class Sigma1Process : public SigmaProcess { |
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431 | |
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432 | public: |
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433 | |
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434 | // Destructor. |
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435 | virtual ~Sigma1Process() {} |
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436 | |
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437 | // Number of final-state particles. |
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438 | virtual int nFinal() const {return 1;}; |
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439 | |
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440 | // Input and complement kinematics for resolved 2 -> 1 process. |
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441 | virtual void set1Kin( double x1in, double x2in, double sHin) { |
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442 | store1Kin( x1in, x2in, sHin); sigmaKin();} |
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443 | |
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444 | // Evaluate sigmaHat(sHat) for resolved 2 -> 1 processes. |
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445 | virtual double sigmaHat() {return 0.;} |
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446 | |
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447 | // Wrapper to sigmaHat, to (a) store current incoming flavours, |
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448 | // (b) convert from GeV^-2 to mb where required, and |
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449 | // (c) convert from |M|^2 to d(sigmaHat)/d(tHat) where required. |
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450 | virtual double sigmaHatWrap(int id1in = 0, int id2in = 0); |
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451 | |
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452 | protected: |
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453 | |
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454 | // Constructor. |
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455 | Sigma1Process() {} |
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456 | |
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457 | // Store kinematics and set scales for resolved 2 -> 1 process. |
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458 | virtual void store1Kin( double x1in, double x2in, double sHin); |
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459 | |
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460 | // Calculate modified masses and four-vectors for matrix elements. |
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461 | virtual bool setupForME(); |
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462 | |
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463 | }; |
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464 | |
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465 | //========================================================================== |
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466 | |
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467 | // Sigma2Process is the base class for 2 -> 2 processes. |
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468 | // It is derived from SigmaProcess. |
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469 | |
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470 | class Sigma2Process : public SigmaProcess { |
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471 | |
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472 | public: |
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473 | |
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474 | // Destructor. |
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475 | virtual ~Sigma2Process() {} |
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476 | |
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477 | // Number of final-state particles. |
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478 | virtual int nFinal() const {return 2;}; |
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479 | |
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480 | // Input and complement kinematics for resolved 2 -> 2 process. |
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481 | virtual void set2Kin( double x1in, double x2in, double sHin, |
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482 | double tHin, double m3in, double m4in, double runBW3in, |
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483 | double runBW4in) { store2Kin( x1in, x2in, sHin, tHin, m3in, m4in, |
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484 | runBW3in, runBW4in); sigmaKin();} |
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485 | |
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486 | // Ditto, but for Multiparton Interactions applications, so different input. |
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487 | virtual void set2KinMPI( double x1in, double x2in, double sHin, |
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488 | double tHin, double uHin, double alpSin, double alpEMin, |
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489 | bool needMasses, double m3in, double m4in) { |
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490 | store2KinMPI( x1in, x2in, sHin, tHin, uHin, alpSin, alpEMin, |
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491 | needMasses, m3in, m4in); sigmaKin();} |
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492 | |
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493 | // Evaluate d(sigmaHat)/d(tHat) for resolved 2 -> 2 processes. |
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494 | virtual double sigmaHat() {return 0.;} |
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495 | |
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496 | // Wrapper to sigmaHat, to (a) store current incoming flavours, |
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497 | // (b) convert from GeV^-2 to mb where required, and |
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498 | // (c) convert from |M|^2 to d(sigmaHat)/d(tHat) where required. |
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499 | virtual double sigmaHatWrap(int id1in = 0, int id2in = 0) { |
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500 | id1 = id1in; id2 = id2in; double sigmaTmp = sigmaHat(); |
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501 | if (convertM2()) sigmaTmp /= 16. * M_PI * sH2; |
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502 | if (convert2mb()) sigmaTmp *= CONVERT2MB; return sigmaTmp;} |
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503 | |
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504 | // Perform kinematics for a Multiparton Interaction, in its rest frame. |
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505 | virtual bool final2KinMPI( int i1Res = 0, int i2Res = 0, Vec4 p1Res = 0., |
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506 | Vec4 p2Res = 0., double m1Res = 0., double m2Res = 0.); |
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507 | |
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508 | protected: |
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509 | |
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510 | // Constructor. |
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511 | Sigma2Process() : tH(0.), uH(0.), tH2(0.), uH2(0.), m3(0.), s3(0.), |
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512 | m4(0.), s4(0.), pT2(0.), runBW3(0.), runBW4(0.) {} |
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513 | |
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514 | // Store kinematics and set scales for resolved 2 -> 2 process. |
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515 | virtual void store2Kin( double x1in, double x2in, double sHin, |
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516 | double tHin, double m3in, double m4in, double runBW3in, |
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517 | double runBW4in); |
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518 | virtual void store2KinMPI( double x1in, double x2in, double sHin, |
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519 | double tHin, double uHin, double alpSin, double alpEMin, |
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520 | bool needMasses, double m3in, double m4in); |
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521 | |
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522 | // Calculate modified masses and four-vectors for matrix elements. |
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523 | virtual bool setupForME(); |
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524 | |
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525 | // Store subprocess kinematics quantities. |
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526 | double tH, uH, tH2, uH2, m3, s3, m4, s4, pT2, runBW3, runBW4; |
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527 | |
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528 | }; |
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529 | |
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530 | //========================================================================== |
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531 | |
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532 | // Sigma3Process is the base class for 2 -> 3 processes. |
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533 | // It is derived from SigmaProcess. |
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534 | |
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535 | class Sigma3Process : public SigmaProcess { |
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536 | |
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537 | public: |
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538 | |
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539 | // Destructor. |
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540 | virtual ~Sigma3Process() {} |
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541 | |
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542 | // Number of final-state particles. |
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543 | virtual int nFinal() const {return 3;}; |
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544 | |
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545 | // Input and complement kinematics for resolved 2 -> 3 process. |
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546 | virtual void set3Kin( double x1in, double x2in, double sHin, |
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547 | Vec4 p3cmIn, Vec4 p4cmIn, Vec4 p5cmIn, double m3in, double m4in, |
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548 | double m5in, double runBW3in, double runBW4in, double runBW5in) { |
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549 | store3Kin( x1in, x2in, sHin, p3cmIn, p4cmIn, p5cmIn, m3in, m4in, m5in, |
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550 | runBW3in, runBW4in, runBW5in); sigmaKin();} |
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551 | |
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552 | // Evaluate d(sigmaHat)/d(tHat) for resolved 2 -> 3 processes. |
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553 | virtual double sigmaHat() {return 0.;} |
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554 | |
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555 | protected: |
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556 | |
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557 | // Constructor. |
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558 | Sigma3Process() {} |
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559 | |
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560 | // Store kinematics and set scales for resolved 2 -> 3 process. |
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561 | virtual void store3Kin( double x1in, double x2in, double sHin, |
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562 | Vec4 p3cmIn, Vec4 p4cmIn, Vec4 p5cmIn, double m3in, double m4in, |
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563 | double m5in, double runBW3in, double runBW4in, double runBW5in); |
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564 | |
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565 | // Calculate modified masses and four-vectors for matrix elements. |
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566 | virtual bool setupForME(); |
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567 | |
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568 | // Store subprocess kinematics quantities. |
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569 | double m3, s3, m4, s4, m5, s5, runBW3, runBW4, runBW5; |
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570 | Vec4 p3cm, p4cm, p5cm; |
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571 | |
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572 | }; |
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573 | |
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574 | //========================================================================== |
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575 | |
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576 | // SigmaLHAProcess is a wrapper class for Les Houches Accord external input. |
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577 | // It is derived from SigmaProcess. |
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578 | |
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579 | class SigmaLHAProcess : public SigmaProcess { |
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580 | |
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581 | public: |
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582 | |
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583 | // Constructor. |
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584 | SigmaLHAProcess() {} |
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585 | |
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586 | // Destructor. |
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587 | virtual ~SigmaLHAProcess() {} |
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588 | |
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589 | // No partonic flux to be set up. |
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590 | virtual bool initFlux() {return true;} |
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591 | |
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592 | // Dummy function: action is put in PhaseSpaceLHA. |
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593 | virtual double sigmaPDF() {return 1.;} |
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594 | |
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595 | // Evaluate weight for decay angular configuration, where relevant. |
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596 | virtual double weightDecay( Event& process, int iResBeg, int iResEnd); |
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597 | |
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598 | // Set scale, when that is missing for an external LHA process. |
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599 | virtual void setScale(); |
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600 | |
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601 | // Info on the subprocess. |
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602 | virtual string name() const {return "Les Houches User Process(es)";} |
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603 | virtual int code() const {return 9999;} |
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604 | |
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605 | // Number of final-state particles depends on current process choice. |
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606 | virtual int nFinal() const; |
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607 | |
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608 | // Answer for these processes not in GeV^-2, so do not do this conversion. |
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609 | virtual bool convert2mb() const {return false;} |
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610 | |
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611 | // Ensure special treatment of Les Houches processes. |
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612 | virtual bool isLHA() const {return true;} |
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613 | |
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614 | // Special treatment needed if negative cross sections allowed. |
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615 | virtual bool allowNegativeSigma() const { |
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616 | return (lhaUpPtr->strategy() < 0);} |
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617 | |
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618 | private: |
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619 | |
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620 | }; |
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621 | |
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622 | //========================================================================== |
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623 | |
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624 | } // end namespace Pythia8 |
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625 | |
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626 | #endif // Pythia8_SigmaProcess_H |
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627 | |
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