1 | // HadronLevel.cc 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 | // Function definitions (not found in the header) for the HadronLevel class. |
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7 | |
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8 | #include "HadronLevel.h" |
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9 | |
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10 | namespace Pythia8 { |
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11 | |
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12 | //========================================================================== |
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13 | |
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14 | // The HadronLevel class. |
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15 | |
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16 | //-------------------------------------------------------------------------- |
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17 | |
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18 | // Constants: could be changed here if desired, but normally should not. |
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19 | // These are of technical nature, as described for each. |
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20 | |
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21 | // For breaking J-J string, pick a Gamma by taking a step with fictitious mass. |
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22 | const double HadronLevel::JJSTRINGM2MAX = 25.; |
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23 | const double HadronLevel::JJSTRINGM2FRAC = 0.1; |
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24 | |
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25 | // Iterate junction rest frame boost until convergence or too many tries. |
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26 | const double HadronLevel::CONVJNREST = 1e-5; |
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27 | const int HadronLevel::NTRYJNREST = 20; |
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28 | |
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29 | // Typical average transvere primary hadron mass <mThad>. |
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30 | const double HadronLevel::MTHAD = 0.9; |
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31 | |
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32 | //-------------------------------------------------------------------------- |
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33 | |
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34 | // Find settings. Initialize HadronLevel classes as required. |
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35 | |
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36 | bool HadronLevel::init(Info* infoPtrIn, Settings& settings, |
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37 | ParticleData* particleDataPtrIn, Rndm* rndmPtrIn, |
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38 | Couplings* couplingsPtrIn, TimeShower* timesDecPtr, |
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39 | RHadrons* rHadronsPtrIn, DecayHandler* decayHandlePtr, |
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40 | vector<int> handledParticles) { |
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41 | |
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42 | // Save pointers. |
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43 | infoPtr = infoPtrIn; |
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44 | particleDataPtr = particleDataPtrIn; |
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45 | rndmPtr = rndmPtrIn; |
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46 | couplingsPtr = couplingsPtrIn; |
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47 | rHadronsPtr = rHadronsPtrIn; |
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48 | |
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49 | // Main flags. |
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50 | doHadronize = settings.flag("HadronLevel:Hadronize"); |
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51 | doDecay = settings.flag("HadronLevel:Decay"); |
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52 | doBoseEinstein = settings.flag("HadronLevel:BoseEinstein"); |
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53 | |
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54 | // Boundary mass between string and ministring handling. |
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55 | mStringMin = settings.parm("HadronLevel:mStringMin"); |
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56 | |
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57 | // For junction processing. |
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58 | eNormJunction = settings.parm("StringFragmentation:eNormJunction"); |
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59 | |
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60 | // Allow R-hadron formation. |
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61 | allowRH = settings.flag("RHadrons:allow"); |
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62 | |
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63 | // Particles that should decay or not before Bose-Einstein stage. |
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64 | widthSepBE = settings.parm("BoseEinstein:widthSep"); |
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65 | |
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66 | // Hadron scattering --rjc |
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67 | doHadronScatter = settings.flag("HadronScatter:scatter"); |
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68 | hsAfterDecay = settings.flag("HadronScatter:afterDecay"); |
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69 | |
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70 | // Initialize auxiliary fragmentation classes. |
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71 | flavSel.init(settings, rndmPtr); |
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72 | pTSel.init(settings, *particleDataPtr, rndmPtr); |
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73 | zSel.init(settings, *particleDataPtr, rndmPtr); |
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74 | |
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75 | // Initialize auxiliary administrative class. |
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76 | colConfig.init(infoPtr, settings, &flavSel); |
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77 | |
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78 | // Initialize string and ministring fragmentation. |
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79 | stringFrag.init(infoPtr, settings, particleDataPtr, rndmPtr, |
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80 | &flavSel, &pTSel, &zSel); |
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81 | ministringFrag.init(infoPtr, settings, particleDataPtr, rndmPtr, |
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82 | &flavSel, &pTSel, &zSel); |
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83 | |
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84 | // Initialize particle decays. |
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85 | decays.init(infoPtr, settings, particleDataPtr, rndmPtr, couplingsPtr, |
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86 | timesDecPtr, &flavSel, decayHandlePtr, handledParticles); |
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87 | |
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88 | // Initialize BoseEinstein. |
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89 | boseEinstein.init(infoPtr, settings, *particleDataPtr); |
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90 | |
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91 | // Initialize HadronScatter --rjc |
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92 | if (doHadronScatter) |
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93 | hadronScatter.init(infoPtr, settings, rndmPtr, particleDataPtr); |
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94 | |
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95 | // Initialize Hidden-Valley fragmentation, if necessary. |
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96 | useHiddenValley = hiddenvalleyFrag.init(infoPtr, settings, |
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97 | particleDataPtr, rndmPtr); |
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98 | |
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99 | // Send flavour and z selection pointers to R-hadron machinery. |
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100 | rHadronsPtr->fragPtrs( &flavSel, &zSel); |
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101 | |
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102 | // Done. |
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103 | return true; |
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104 | |
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105 | } |
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106 | |
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107 | //-------------------------------------------------------------------------- |
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108 | |
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109 | // Hadronize and decay the next parton-level. |
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110 | |
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111 | bool HadronLevel::next( Event& event) { |
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112 | |
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113 | // Do Hidden-Valley fragmentation, if necessary. |
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114 | if (useHiddenValley) hiddenvalleyFrag.fragment(event); |
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115 | |
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116 | // Colour-octet onia states must be decayed to singlet + gluon. |
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117 | if (!decayOctetOnia(event)) return false; |
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118 | |
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119 | // Possibility of hadronization inside decay, but then no BE second time. |
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120 | // Hadron scattering, first pass only --rjc |
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121 | bool moreToDo, firstPass = true; |
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122 | bool doBoseEinsteinNow = doBoseEinstein; |
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123 | do { |
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124 | moreToDo = false; |
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125 | |
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126 | // First part: string fragmentation. |
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127 | if (doHadronize) { |
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128 | |
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129 | // Find the complete colour singlet configuration of the event. |
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130 | if (!findSinglets( event)) return false; |
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131 | |
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132 | // Fragment off R-hadrons, if necessary. |
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133 | if (allowRH && !rHadronsPtr->produce( colConfig, event)) |
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134 | return false; |
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135 | |
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136 | // Process all colour singlet (sub)system |
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137 | for (int iSub = 0; iSub < colConfig.size(); ++iSub) { |
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138 | |
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139 | // Collect sequentially all partons in a colour singlet subsystem. |
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140 | colConfig.collect(iSub, event); |
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141 | |
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142 | // String fragmentation of each colour singlet (sub)system. |
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143 | if ( colConfig[iSub].massExcess > mStringMin ) { |
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144 | if (!stringFrag.fragment( iSub, colConfig, event)) return false; |
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145 | |
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146 | // Low-mass string treated separately. Tell if diffractive system. |
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147 | } else { |
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148 | bool isDiff = infoPtr->isDiffractiveA() |
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149 | || infoPtr->isDiffractiveB(); |
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150 | if (!ministringFrag.fragment( iSub, colConfig, event, isDiff)) |
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151 | return false; |
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152 | } |
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153 | } |
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154 | } |
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155 | |
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156 | // Hadron scattering --rjc |
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157 | if (doHadronScatter && !hsAfterDecay && firstPass) |
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158 | hadronScatter.scatter(event); |
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159 | |
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160 | // Second part: sequential decays of short-lived particles (incl. K0). |
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161 | if (doDecay) { |
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162 | |
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163 | // Loop through all entries to find those that should decay. |
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164 | int iDec = 0; |
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165 | do { |
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166 | Particle& decayer = event[iDec]; |
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167 | if ( decayer.isFinal() && decayer.canDecay() && decayer.mayDecay() |
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168 | && (decayer.mWidth() > widthSepBE || decayer.idAbs() == 311) ) { |
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169 | decays.decay( iDec, event); |
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170 | if (decays.moreToDo()) moreToDo = true; |
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171 | } |
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172 | } while (++iDec < event.size()); |
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173 | } |
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174 | |
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175 | // Hadron scattering --rjc |
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176 | if (doHadronScatter && hsAfterDecay && firstPass) |
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177 | hadronScatter.scatter(event); |
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178 | |
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179 | // Third part: include Bose-Einstein effects among current particles. |
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180 | if (doBoseEinsteinNow) { |
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181 | if (!boseEinstein.shiftEvent(event)) return false; |
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182 | doBoseEinsteinNow = false; |
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183 | } |
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184 | |
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185 | // Fourth part: sequential decays also of long-lived particles. |
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186 | if (doDecay) { |
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187 | |
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188 | // Loop through all entries to find those that should decay. |
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189 | int iDec = 0; |
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190 | do { |
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191 | Particle& decayer = event[iDec]; |
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192 | if ( decayer.isFinal() && decayer.canDecay() && decayer.mayDecay() ) { |
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193 | decays.decay( iDec, event); |
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194 | if (decays.moreToDo()) moreToDo = true; |
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195 | } |
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196 | } while (++iDec < event.size()); |
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197 | } |
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198 | |
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199 | // Normally done first time around, but sometimes not (e.g. Upsilon). |
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200 | } while (moreToDo); |
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201 | |
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202 | // Done. |
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203 | return true; |
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204 | |
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205 | } |
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206 | |
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207 | //-------------------------------------------------------------------------- |
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208 | |
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209 | // Allow more decays if on/off switches changed. |
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210 | // Note: does not do sequential hadronization, e.g. for Upsilon. |
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211 | |
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212 | bool HadronLevel::moreDecays( Event& event) { |
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213 | |
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214 | // Colour-octet onia states must be decayed to singlet + gluon. |
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215 | if (!decayOctetOnia(event)) return false; |
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216 | |
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217 | // Loop through all entries to find those that should decay. |
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218 | int iDec = 0; |
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219 | do { |
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220 | if ( event[iDec].isFinal() && event[iDec].canDecay() |
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221 | && event[iDec].mayDecay() ) decays.decay( iDec, event); |
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222 | } while (++iDec < event.size()); |
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223 | |
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224 | // Done. |
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225 | return true; |
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226 | |
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227 | } |
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228 | |
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229 | //-------------------------------------------------------------------------- |
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230 | |
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231 | // Decay colour-octet onium states. |
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232 | |
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233 | bool HadronLevel::decayOctetOnia(Event& event) { |
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234 | |
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235 | // Onium states to be decayed. |
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236 | int idOnium[6] = { 9900443, 9900441, 9910441, |
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237 | 9900553, 9900551, 9910551 }; |
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238 | |
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239 | // Loop over particles and identify onia. |
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240 | for (int iDec = 0; iDec < event.size(); ++iDec) |
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241 | if (event[iDec].isFinal()) { |
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242 | int id = event[iDec].id(); |
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243 | bool isOnium = false; |
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244 | for (int j = 0; j < 6; ++j) if (id == idOnium[j]) isOnium = true; |
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245 | |
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246 | // Decay any onia encountered. |
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247 | if (isOnium) { |
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248 | if (!decays.decay( iDec, event)) return false; |
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249 | |
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250 | // Set colour flow by hand: gluon inherits octet-onium state. |
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251 | int iGlu = event.size() - 1; |
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252 | event[iGlu].cols( event[iDec].col(), event[iDec].acol() ); |
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253 | } |
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254 | } |
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255 | |
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256 | // Done. |
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257 | return true; |
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258 | |
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259 | } |
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260 | |
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261 | //-------------------------------------------------------------------------- |
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262 | |
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263 | // Trace colour flow in the event to form colour singlet subsystems. |
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264 | |
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265 | bool HadronLevel::findSinglets(Event& event) { |
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266 | |
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267 | // Find a list of final partons and of all colour ends and gluons. |
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268 | iColEnd.resize(0); |
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269 | iAcolEnd.resize(0); |
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270 | iColAndAcol.resize(0); |
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271 | for (int i = 0; i < event.size(); ++i) if (event[i].isFinal()) { |
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272 | if (event[i].col() > 0 && event[i].acol() > 0) iColAndAcol.push_back(i); |
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273 | else if (event[i].col() > 0) iColEnd.push_back(i); |
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274 | else if (event[i].acol() > 0) iAcolEnd.push_back(i); |
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275 | } |
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276 | |
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277 | // Begin arrange the partons into separate colour singlets. |
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278 | colConfig.clear(); |
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279 | iPartonJun.resize(0); |
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280 | iPartonAntiJun.resize(0); |
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281 | |
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282 | // Junctions: loop over them, and identify kind. |
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283 | for (int iJun = 0; iJun < event.sizeJunction(); ++iJun) |
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284 | if (event.remainsJunction(iJun)) { |
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285 | event.remainsJunction(iJun, false); |
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286 | int kindJun = event.kindJunction(iJun); |
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287 | iParton.resize(0); |
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288 | |
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289 | // Loop over junction legs. |
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290 | for (int iCol = 0; iCol < 3; ++iCol) { |
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291 | int indxCol = event.colJunction(iJun, iCol); |
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292 | iParton.push_back( -(10 + 10 * iJun + iCol) ); |
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293 | // Junctions: find color ends. |
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294 | if (kindJun % 2 == 1 && !traceFromAcol(indxCol, event, iJun, iCol)) |
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295 | return false; |
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296 | // Antijunctions: find anticolor ends. |
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297 | if (kindJun % 2 == 0 && !traceFromCol(indxCol, event, iJun, iCol)) |
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298 | return false; |
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299 | } |
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300 | |
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301 | // Reject triple- and higher-junction systems (physics not implemented). |
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302 | int otherJun = 0; |
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303 | for (int i = 0; i < int(iParton.size()); ++i) |
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304 | if (iParton[i] < 0 && abs(iParton[i]) / 10 != iJun + 1) { |
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305 | if (otherJun == 0) otherJun = abs(iParton[i]) / 10; |
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306 | else if (abs(iParton[i]) / 10 != otherJun) { |
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307 | infoPtr->errorMsg("Error in HadronLevel::findSinglets: " |
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308 | "too many junction-junction connections"); |
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309 | return false; |
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310 | } |
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311 | } |
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312 | |
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313 | // Keep in memory a junction hooked up with an antijunction, |
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314 | // else store found single-junction system. |
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315 | int nNeg = 0; |
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316 | for (int i = 0; i < int(iParton.size()); ++i) if (iParton[i] < 0) |
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317 | ++nNeg; |
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318 | if (nNeg > 3 && kindJun % 2 == 1) { |
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319 | for (int i = 0; i < int(iParton.size()); ++i) |
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320 | iPartonJun.push_back(iParton[i]); |
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321 | } else if (nNeg > 3 && kindJun % 2 == 0) { |
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322 | for (int i = 0; i < int(iParton.size()); ++i) |
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323 | iPartonAntiJun.push_back(iParton[i]); |
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324 | } else { |
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325 | // A junction may be eliminated by insert if two quarks are nearby. |
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326 | int nJunOld = event.sizeJunction(); |
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327 | if (!colConfig.insert(iParton, event)) return false; |
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328 | if (event.sizeJunction() < nJunOld) --iJun; |
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329 | } |
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330 | } |
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331 | |
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332 | // Split junction-antijunction system into two, and store those. |
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333 | // (Only one system in extreme cases, and then second empty.) |
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334 | if (iPartonJun.size() > 0 && iPartonAntiJun.size() > 0) { |
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335 | if (!splitJunctionPair(event)) return false; |
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336 | if (!colConfig.insert(iPartonJun, event)) return false; |
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337 | if (iPartonAntiJun.size() > 0) |
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338 | if (!colConfig.insert(iPartonAntiJun, event)) return false; |
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339 | // Error if only one of junction and antijuction left here. |
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340 | } else if (iPartonJun.size() > 0 || iPartonAntiJun.size() > 0) { |
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341 | infoPtr->errorMsg("Error in HadronLevel::findSinglets: " |
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342 | "unmatched (anti)junction"); |
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343 | return false; |
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344 | } |
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345 | |
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346 | // Open strings: pick up each colour end and trace to its anticolor end. |
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347 | for (int iEnd = 0; iEnd < int(iColEnd.size()); ++iEnd) { |
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348 | iParton.resize(0); |
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349 | iParton.push_back( iColEnd[iEnd] ); |
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350 | int indxCol = event[ iColEnd[iEnd] ].col(); |
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351 | if (!traceFromCol(indxCol, event)) return false; |
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352 | |
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353 | // Store found open string system. Analyze its properties. |
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354 | if (!colConfig.insert(iParton, event)) return false; |
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355 | } |
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356 | |
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357 | // Closed strings : begin at any gluon and trace until back at it. |
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358 | while (iColAndAcol.size() > 0) { |
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359 | iParton.resize(0); |
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360 | iParton.push_back( iColAndAcol[0] ); |
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361 | int indxCol = event[ iColAndAcol[0] ].col(); |
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362 | int indxAcol = event[ iColAndAcol[0] ].acol(); |
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363 | iColAndAcol[0] = iColAndAcol.back(); |
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364 | iColAndAcol.pop_back(); |
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365 | if (!traceInLoop(indxCol, indxAcol, event)) return false; |
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366 | |
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367 | // Store found closed string system. Analyze its properties. |
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368 | if (!colConfig.insert(iParton, event)) return false; |
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369 | } |
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370 | |
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371 | // Done. |
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372 | return true; |
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373 | |
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374 | } |
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375 | |
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376 | //-------------------------------------------------------------------------- |
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377 | |
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378 | // Trace a colour line, from a colour to an anticolour. |
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379 | |
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380 | bool HadronLevel::traceFromCol(int indxCol, Event& event, int iJun, |
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381 | int iCol) { |
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382 | |
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383 | // Junction kind, if any. |
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384 | int kindJun = (iJun >= 0) ? event.kindJunction(iJun) : 0; |
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385 | |
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386 | // Begin to look for a matching anticolour. |
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387 | int loop = 0; |
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388 | int loopMax = iColAndAcol.size() + 2; |
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389 | bool hasFound = false; |
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390 | do { |
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391 | ++loop; |
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392 | hasFound= false; |
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393 | |
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394 | // First check list of matching anticolour ends. |
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395 | for (int i = 0; i < int(iAcolEnd.size()); ++i) |
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396 | if (event[ iAcolEnd[i] ].acol() == indxCol) { |
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397 | iParton.push_back( iAcolEnd[i] ); |
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398 | indxCol = 0; |
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399 | iAcolEnd[i] = iAcolEnd.back(); |
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400 | iAcolEnd.pop_back(); |
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401 | hasFound = true; |
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402 | break; |
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403 | } |
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404 | |
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405 | // Then check list of intermediate gluons. |
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406 | if (!hasFound) |
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407 | for (int i = 0; i < int(iColAndAcol.size()); ++i) |
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408 | if (event[ iColAndAcol[i] ].acol() == indxCol) { |
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409 | iParton.push_back( iColAndAcol[i] ); |
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410 | |
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411 | // Update to new colour. Remove gluon. |
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412 | indxCol = event[ iColAndAcol[i] ].col(); |
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413 | if (kindJun > 0) event.endColJunction(iJun, iCol, indxCol); |
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414 | iColAndAcol[i] = iColAndAcol.back(); |
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415 | iColAndAcol.pop_back(); |
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416 | hasFound = true; |
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417 | break; |
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418 | } |
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419 | |
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420 | // In a pinch, check list of opposite-sign junction end colours. |
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421 | // Store in iParton list as -(10 + 10 * iAntiJun + iAntiLeg). |
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422 | if (!hasFound && kindJun % 2 == 0 && event.sizeJunction() > 1) |
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423 | for (int iAntiJun = 0; iAntiJun < event.sizeJunction(); ++iAntiJun) |
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424 | if (iAntiJun != iJun && event.kindJunction(iAntiJun) %2 == 1) |
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425 | for (int iColAnti = 0; iColAnti < 3; ++iColAnti) |
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426 | if (event.endColJunction(iAntiJun, iColAnti) == indxCol) { |
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427 | iParton.push_back( -(10 + 10 * iAntiJun + iColAnti) ); |
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428 | indxCol = 0; |
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429 | hasFound = true; |
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430 | break; |
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431 | } |
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432 | |
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433 | // Keep on tracing via gluons until reached end of leg. |
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434 | } while (hasFound && indxCol > 0 && loop < loopMax); |
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435 | |
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436 | // Something went wrong in colour tracing. |
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437 | if (!hasFound || loop == loopMax) { |
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438 | infoPtr->errorMsg("Error in HadronLevel::traceFromCol: " |
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439 | "colour tracing failed"); |
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440 | return false; |
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441 | } |
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442 | |
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443 | // Done. |
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444 | return true; |
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445 | |
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446 | } |
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447 | |
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448 | //-------------------------------------------------------------------------- |
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449 | |
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450 | // Trace a colour line, from an anticolour to a colour. |
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451 | |
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452 | bool HadronLevel::traceFromAcol(int indxCol, Event& event, int iJun, |
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453 | int iCol) { |
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454 | |
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455 | // Junction kind, if any. |
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456 | int kindJun = (iJun >= 0) ? event.kindJunction(iJun) : 0; |
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457 | |
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458 | // Begin to look for a matching colour. |
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459 | int loop = 0; |
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460 | int loopMax = iColAndAcol.size() + 2; |
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461 | bool hasFound = false; |
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462 | do { |
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463 | ++loop; |
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464 | hasFound= false; |
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465 | |
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466 | // First check list of matching colour ends. |
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467 | for (int i = 0; i < int(iColEnd.size()); ++i) |
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468 | if (event[ iColEnd[i] ].col() == indxCol) { |
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469 | iParton.push_back( iColEnd[i] ); |
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470 | indxCol = 0; |
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471 | iColEnd[i] = iColEnd.back(); |
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472 | iColEnd.pop_back(); |
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473 | hasFound = true; |
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474 | break; |
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475 | } |
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476 | |
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477 | // Then check list of intermediate gluons. |
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478 | if (!hasFound) |
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479 | for (int i = 0; i < int(iColAndAcol.size()); ++i) |
---|
480 | if (event[ iColAndAcol[i] ].col() == indxCol) { |
---|
481 | iParton.push_back( iColAndAcol[i] ); |
---|
482 | // Update to new colour. Remove gluon. |
---|
483 | indxCol = event[ iColAndAcol[i] ].acol(); |
---|
484 | if (kindJun > 0) event.endColJunction(iJun, iCol, indxCol); |
---|
485 | iColAndAcol[i] = iColAndAcol.back(); |
---|
486 | iColAndAcol.pop_back(); |
---|
487 | hasFound = true; |
---|
488 | break; |
---|
489 | } |
---|
490 | |
---|
491 | // In a pinch, check list of opposite-sign junction end colours. |
---|
492 | // Store in iParton list as -(10 + 10 * iAntiJun + iLeg). |
---|
493 | if (!hasFound && kindJun % 2 == 1 && event.sizeJunction() > 1) |
---|
494 | for (int iAntiJun = 0; iAntiJun < event.sizeJunction(); ++iAntiJun) |
---|
495 | if (iAntiJun != iJun && event.kindJunction(iAntiJun) % 2 == 0) |
---|
496 | for (int iColAnti = 0; iColAnti < 3; ++iColAnti) |
---|
497 | if (event.endColJunction(iAntiJun, iColAnti) == indxCol) { |
---|
498 | iParton.push_back( -(10 + 10 * iAntiJun + iColAnti) ); |
---|
499 | indxCol = 0; |
---|
500 | hasFound = true; |
---|
501 | break; |
---|
502 | } |
---|
503 | |
---|
504 | // Keep on tracing via gluons until reached end of leg. |
---|
505 | } while (hasFound && indxCol > 0 && loop < loopMax); |
---|
506 | |
---|
507 | // Something went wrong in colour tracing. |
---|
508 | if (!hasFound || loop == loopMax) { |
---|
509 | infoPtr->errorMsg("Error in HadronLevel::traceFromAcol: " |
---|
510 | "colour tracing failed"); |
---|
511 | return false; |
---|
512 | } |
---|
513 | |
---|
514 | // Done. |
---|
515 | return true; |
---|
516 | |
---|
517 | } |
---|
518 | |
---|
519 | //-------------------------------------------------------------------------- |
---|
520 | |
---|
521 | // Trace a colour loop, from a colour back to the anticolour of the same. |
---|
522 | |
---|
523 | bool HadronLevel::traceInLoop(int indxCol, int indxAcol, Event& event) { |
---|
524 | |
---|
525 | // Move around until back where begun. |
---|
526 | int loop = 0; |
---|
527 | int loopMax = iColAndAcol.size() + 2; |
---|
528 | bool hasFound = false; |
---|
529 | do { |
---|
530 | ++loop; |
---|
531 | hasFound= false; |
---|
532 | |
---|
533 | // Check list of gluons. |
---|
534 | for (int i = 0; i < int(iColAndAcol.size()); ++i) |
---|
535 | if (event[ iColAndAcol[i] ].acol() == indxCol) { |
---|
536 | iParton.push_back( iColAndAcol[i] ); |
---|
537 | indxCol = event[ iColAndAcol[i] ].col(); |
---|
538 | iColAndAcol[i] = iColAndAcol.back(); |
---|
539 | iColAndAcol.pop_back(); |
---|
540 | hasFound = true; |
---|
541 | break; |
---|
542 | } |
---|
543 | } while (hasFound && indxCol != indxAcol && loop < loopMax); |
---|
544 | |
---|
545 | // Something went wrong in colour tracing. |
---|
546 | if (!hasFound || loop == loopMax) { |
---|
547 | infoPtr->errorMsg("Error in HadronLevel::traceInLoop: " |
---|
548 | "colour tracing failed"); |
---|
549 | return false; |
---|
550 | } |
---|
551 | |
---|
552 | // Done. |
---|
553 | return true; |
---|
554 | |
---|
555 | } |
---|
556 | |
---|
557 | //-------------------------------------------------------------------------- |
---|
558 | |
---|
559 | // Split junction-antijunction system into two, or simplify other way. |
---|
560 | |
---|
561 | bool HadronLevel::splitJunctionPair(Event& event) { |
---|
562 | |
---|
563 | // Construct separate index arrays for the three junction legs. |
---|
564 | int identJun = (-iPartonJun[0])/10; |
---|
565 | iJunLegA.resize(0); |
---|
566 | iJunLegB.resize(0); |
---|
567 | iJunLegC.resize(0); |
---|
568 | int leg = -1; |
---|
569 | for (int i = 0; i < int(iPartonJun.size()); ++ i) { |
---|
570 | if ( (-iPartonJun[i])/10 == identJun) ++leg; |
---|
571 | if (leg == 0) iJunLegA.push_back( iPartonJun[i] ); |
---|
572 | else if (leg == 1) iJunLegB.push_back( iPartonJun[i] ); |
---|
573 | else iJunLegC.push_back( iPartonJun[i] ); |
---|
574 | } |
---|
575 | |
---|
576 | // Construct separate index arrays for the three antijunction legs. |
---|
577 | int identAnti = (-iPartonAntiJun[0])/10; |
---|
578 | iAntiLegA.resize(0); |
---|
579 | iAntiLegB.resize(0); |
---|
580 | iAntiLegC.resize(0); |
---|
581 | leg = -1; |
---|
582 | for (int i = 0; i < int(iPartonAntiJun.size()); ++ i) { |
---|
583 | if ( (-iPartonAntiJun[i])/10 == identAnti) ++leg; |
---|
584 | if (leg == 0) iAntiLegA.push_back( iPartonAntiJun[i] ); |
---|
585 | else if (leg == 1) iAntiLegB.push_back( iPartonAntiJun[i] ); |
---|
586 | else iAntiLegC.push_back( iPartonAntiJun[i] ); |
---|
587 | } |
---|
588 | |
---|
589 | // Find interjunction legs, i.e. between junction and antijunction. |
---|
590 | int nMatch = 0; |
---|
591 | int legJun[3], legAnti[3], nGluLeg[3]; |
---|
592 | if (iJunLegA.back() < 0) { legJun[nMatch] = 0; |
---|
593 | legAnti[nMatch] = (-iJunLegA.back())%10; ++nMatch;} |
---|
594 | if (iJunLegB.back() < 0) { legJun[nMatch] = 1; |
---|
595 | legAnti[nMatch] = (-iJunLegB.back())%10; ++nMatch;} |
---|
596 | if (iJunLegC.back() < 0) { legJun[nMatch] = 2; |
---|
597 | legAnti[nMatch] = (-iJunLegC.back())%10; ++nMatch;} |
---|
598 | |
---|
599 | // Loop over interjunction legs. |
---|
600 | for (int iMatch = 0; iMatch < nMatch; ++iMatch) { |
---|
601 | vector<int>& iJunLeg = (legJun[iMatch] == 0) ? iJunLegA |
---|
602 | : ( (legJun[iMatch] == 1) ? iJunLegB : iJunLegC ); |
---|
603 | vector<int>& iAntiLeg = (legAnti[iMatch] == 0) ? iAntiLegA |
---|
604 | : ( (legAnti[iMatch] == 1) ? iAntiLegB : iAntiLegC ); |
---|
605 | |
---|
606 | // Find number of gluons on each. Do nothing for now if none. |
---|
607 | nGluLeg[iMatch] = iJunLeg.size() + iAntiLeg.size() - 4; |
---|
608 | if (nGluLeg[iMatch] == 0) continue; |
---|
609 | |
---|
610 | // Else pick up the gluons on the interjunction leg in order. |
---|
611 | iGluLeg.resize(0); |
---|
612 | for (int i = 1; i < int(iJunLeg.size()) - 1; ++i) |
---|
613 | iGluLeg.push_back( iJunLeg[i] ); |
---|
614 | for (int i = int(iAntiLeg.size()) - 2; i > 0; --i) |
---|
615 | iGluLeg.push_back( iAntiLeg[i] ); |
---|
616 | |
---|
617 | // Remove those gluons from the junction/antijunction leg lists. |
---|
618 | iJunLeg.resize(1); |
---|
619 | iAntiLeg.resize(1); |
---|
620 | |
---|
621 | // Pick a new quark at random; for simplicity no diquarks. |
---|
622 | int idQ = flavSel.pickLightQ(); |
---|
623 | int colQ, acolQ; |
---|
624 | |
---|
625 | // If one gluon on leg, split it into a collinear q-qbar pair. |
---|
626 | if (iGluLeg.size() == 1) { |
---|
627 | |
---|
628 | // Store the new q qbar pair, sharing gluon colour and momentum. |
---|
629 | colQ = event[ iGluLeg[0] ].col(); |
---|
630 | acolQ = event[ iGluLeg[0] ].acol(); |
---|
631 | Vec4 pQ = 0.5 * event[ iGluLeg[0] ].p(); |
---|
632 | double mQ = 0.5 * event[ iGluLeg[0] ].m(); |
---|
633 | int iQ = event.append( idQ, 75, iGluLeg[0], 0, 0, 0, colQ, 0, pQ, mQ ); |
---|
634 | int iQbar = event.append( -idQ, 75, iGluLeg[0], 0, 0, 0, 0, acolQ, |
---|
635 | pQ, mQ ); |
---|
636 | |
---|
637 | // Mark split gluon and update junction and antijunction legs. |
---|
638 | event[ iGluLeg[0] ].statusNeg(); |
---|
639 | event[ iGluLeg[0] ].daughters( iQ, iQbar); |
---|
640 | iJunLeg.push_back(iQ); |
---|
641 | iAntiLeg.push_back(iQbar); |
---|
642 | |
---|
643 | // If several gluons on the string, decide which g-g region to split up. |
---|
644 | } else { |
---|
645 | |
---|
646 | // Evaluate mass-squared for all adjacent gluon pairs. |
---|
647 | m2Pair.resize(0); |
---|
648 | double m2Sum = 0.; |
---|
649 | for (int i = 0; i < int(iGluLeg.size()) - 1; ++i) { |
---|
650 | double m2Now = 0.5 * event[ iGluLeg[i] ].p() |
---|
651 | * event[ iGluLeg[i + 1] ].p(); |
---|
652 | m2Pair.push_back(m2Now); |
---|
653 | m2Sum += m2Now; |
---|
654 | } |
---|
655 | |
---|
656 | // Pick breakup region with probability proportional to mass-squared. |
---|
657 | double m2Reg = m2Sum * rndmPtr->flat(); |
---|
658 | int iReg = -1; |
---|
659 | do m2Reg -= m2Pair[++iReg]; |
---|
660 | while (m2Reg > 0. && iReg < int(iGluLeg.size()) - 1); |
---|
661 | m2Reg = m2Pair[iReg]; |
---|
662 | |
---|
663 | // Pick breaking point of string in chosen region (symmetrically). |
---|
664 | double m2Temp = min( JJSTRINGM2MAX, JJSTRINGM2FRAC * m2Reg); |
---|
665 | double xPos = 0.5; |
---|
666 | double xNeg = 0.5; |
---|
667 | do { |
---|
668 | double zTemp = zSel.zFrag( idQ, 0, m2Temp); |
---|
669 | xPos = 1. - zTemp; |
---|
670 | xNeg = m2Temp / (zTemp * m2Reg); |
---|
671 | } while (xNeg > 1.); |
---|
672 | if (rndmPtr->flat() > 0.5) swap(xPos, xNeg); |
---|
673 | |
---|
674 | // Pick up two "mother" gluons of breakup. Mark them decayed. |
---|
675 | Particle& gJun = event[ iGluLeg[iReg] ]; |
---|
676 | Particle& gAnti = event[ iGluLeg[iReg + 1] ]; |
---|
677 | gJun.statusNeg(); |
---|
678 | gAnti.statusNeg(); |
---|
679 | int dau1 = event.size(); |
---|
680 | gJun.daughters(dau1, dau1 + 3); |
---|
681 | gAnti.daughters(dau1, dau1 + 3); |
---|
682 | int mother1 = min( iGluLeg[iReg], iGluLeg[iReg + 1]); |
---|
683 | int mother2 = max( iGluLeg[iReg], iGluLeg[iReg + 1]); |
---|
684 | |
---|
685 | // Can keep one of old colours but need one new so unambiguous. |
---|
686 | colQ = gJun.acol(); |
---|
687 | acolQ = event.nextColTag(); |
---|
688 | |
---|
689 | // Store copied gluons with reduced momenta. |
---|
690 | int iGjun = event.append( 21, 75, mother1, mother2, 0, 0, |
---|
691 | gJun.col(), gJun.acol(), (1. - 0.5 * xPos) * gJun.p(), |
---|
692 | (1. - 0.5 * xPos) * gJun.m()); |
---|
693 | int iGanti = event.append( 21, 75, mother1, mother2, 0, 0, |
---|
694 | acolQ, gAnti.acol(), (1. - 0.5 * xNeg) * gAnti.p(), |
---|
695 | (1. - 0.5 * xNeg) * gAnti.m()); |
---|
696 | |
---|
697 | // Store the new q qbar pair with remaining momenta. |
---|
698 | int iQ = event.append( idQ, 75, mother1, mother2, 0, 0, |
---|
699 | colQ, 0, 0.5 * xNeg * gAnti.p(), 0.5 * xNeg * gAnti.m() ); |
---|
700 | int iQbar = event.append( -idQ, 75, mother1, mother2, 0, 0, |
---|
701 | 0, acolQ, 0.5 * xPos * gJun.p(), 0.5 * xPos * gJun.m() ); |
---|
702 | |
---|
703 | // Update junction and antijunction legs with gluons and quarks. |
---|
704 | for (int i = 0; i < iReg; ++i) |
---|
705 | iJunLeg.push_back( iGluLeg[i] ); |
---|
706 | iJunLeg.push_back(iGjun); |
---|
707 | iJunLeg.push_back(iQ); |
---|
708 | for (int i = int(iGluLeg.size()) - 1; i > iReg + 1; --i) |
---|
709 | iAntiLeg.push_back( iGluLeg[i] ); |
---|
710 | iAntiLeg.push_back(iGanti); |
---|
711 | iAntiLeg.push_back(iQbar); |
---|
712 | } |
---|
713 | |
---|
714 | // Update end colours for both g -> q qbar and g g -> g g q qbar. |
---|
715 | event.endColJunction(identJun - 1, legJun[iMatch], colQ); |
---|
716 | event.endColJunction(identAnti - 1, legAnti[iMatch], acolQ); |
---|
717 | } |
---|
718 | |
---|
719 | // Update list of interjunction legs after splittings above. |
---|
720 | int iMatchUp = 0; |
---|
721 | while (iMatchUp < nMatch) { |
---|
722 | if (nGluLeg[iMatchUp] > 0) { |
---|
723 | for (int i = iMatchUp; i < nMatch - 1; ++i) { |
---|
724 | legJun[i] = legJun[i + 1]; |
---|
725 | legAnti[i] = legAnti[i + 1]; |
---|
726 | nGluLeg[i] = nGluLeg[i + 1]; |
---|
727 | } --nMatch; |
---|
728 | } else ++iMatchUp; |
---|
729 | } |
---|
730 | |
---|
731 | // Should not ever have three empty interjunction legs. |
---|
732 | if (nMatch == 3) { |
---|
733 | infoPtr->errorMsg("Error in HadronLevel::splitJunctionPair: " |
---|
734 | "three empty junction-junction legs"); |
---|
735 | return false; |
---|
736 | } |
---|
737 | |
---|
738 | // If two legs are empty, then collapse system to a single string. |
---|
739 | if (nMatch == 2) { |
---|
740 | int legJunLeft = 3 - legJun[0] - legJun[1]; |
---|
741 | int legAntiLeft = 3 - legAnti[0] - legAnti[1]; |
---|
742 | vector<int>& iJunLeg = (legJunLeft == 0) ? iJunLegA |
---|
743 | : ( (legJunLeft == 1) ? iJunLegB : iJunLegC ); |
---|
744 | vector<int>& iAntiLeg = (legAntiLeft == 0) ? iAntiLegA |
---|
745 | : ( (legAntiLeft == 1) ? iAntiLegB : iAntiLegC ); |
---|
746 | iPartonJun.resize(0); |
---|
747 | for (int i = int(iJunLeg.size()) - 1; i > 0; --i) |
---|
748 | iPartonJun.push_back( iJunLeg[i] ); |
---|
749 | for (int i = 1; i < int(iAntiLeg.size()); ++i) |
---|
750 | iPartonJun.push_back( iAntiLeg[i] ); |
---|
751 | |
---|
752 | // Match up the colours where the strings are joined. |
---|
753 | int iColJoin = iJunLeg[1]; |
---|
754 | int iAcolJoin = iAntiLeg[1]; |
---|
755 | event[iAcolJoin].acol( event[iColJoin].col() ); |
---|
756 | |
---|
757 | // Other string system empty. Remove junctions from their list. Done. |
---|
758 | iPartonAntiJun.resize(0); |
---|
759 | event.eraseJunction( max(identJun, identAnti) - 1); |
---|
760 | event.eraseJunction( min(identJun, identAnti) - 1); |
---|
761 | return true; |
---|
762 | } |
---|
763 | |
---|
764 | // If one leg is empty then, depending on string length, either |
---|
765 | // (a) annihilate junction and antijunction into two simple strings, or |
---|
766 | // (b) split the empty leg by borrowing energy from nearby legs. |
---|
767 | if (nMatch == 1) { |
---|
768 | |
---|
769 | // Identify the two external legs of either junction. |
---|
770 | vector<int>& iJunLeg0 = (legJun[0] == 0) ? iJunLegB : iJunLegA; |
---|
771 | vector<int>& iJunLeg1 = (legJun[0] == 2) ? iJunLegB : iJunLegC; |
---|
772 | vector<int>& iAntiLeg0 = (legAnti[0] == 0) ? iAntiLegB : iAntiLegA; |
---|
773 | vector<int>& iAntiLeg1 = (legAnti[0] == 2) ? iAntiLegB : iAntiLegC; |
---|
774 | |
---|
775 | // Simplified procedure: mainly study first parton on each leg. |
---|
776 | Vec4 pJunLeg0 = event[ iJunLeg0[1] ].p(); |
---|
777 | Vec4 pJunLeg1 = event[ iJunLeg1[1] ].p(); |
---|
778 | Vec4 pAntiLeg0 = event[ iAntiLeg0[1] ].p(); |
---|
779 | Vec4 pAntiLeg1 = event[ iAntiLeg1[1] ].p(); |
---|
780 | |
---|
781 | // Starting frame hopefully intermediate to two junction directions. |
---|
782 | Vec4 pStart = pJunLeg0 / pJunLeg0.e() + pJunLeg1 / pJunLeg1.e() |
---|
783 | + pAntiLeg0 / pAntiLeg0.e() + pAntiLeg1 / pAntiLeg1.e(); |
---|
784 | |
---|
785 | // Loop over iteration to junction/antijunction rest frames (JRF/ARF). |
---|
786 | RotBstMatrix MtoJRF, MtoARF; |
---|
787 | Vec4 pInJRF[3], pInARF[3]; |
---|
788 | for (int iJun = 0; iJun < 2; ++iJun) { |
---|
789 | int offset = (iJun == 0) ? 0 : 2; |
---|
790 | |
---|
791 | // Iterate from system rest frame towards the junction rest frame. |
---|
792 | RotBstMatrix MtoRF, Mstep; |
---|
793 | MtoRF.bstback(pStart); |
---|
794 | Vec4 pInRF[4]; |
---|
795 | int iter = 0; |
---|
796 | do { |
---|
797 | ++iter; |
---|
798 | |
---|
799 | // Find rest-frame momenta on the three sides of the junction. |
---|
800 | // Only consider first parton on each leg, for simplicity. |
---|
801 | pInRF[0 + offset] = pJunLeg0; |
---|
802 | pInRF[1 + offset] = pJunLeg1; |
---|
803 | pInRF[2 - offset] = pAntiLeg0; |
---|
804 | pInRF[3 - offset] = pAntiLeg1; |
---|
805 | for (int i = 0; i < 4; ++i) pInRF[i].rotbst(MtoRF); |
---|
806 | |
---|
807 | // For third side add both legs beyond other junction, weighted. |
---|
808 | double wt2 = 1. - exp( -pInRF[2].e() / eNormJunction); |
---|
809 | double wt3 = 1. - exp( -pInRF[3].e() / eNormJunction); |
---|
810 | pInRF[2] = wt2 * pInRF[2] + wt3 * pInRF[3]; |
---|
811 | |
---|
812 | // Find new junction rest frame from the set of momenta. |
---|
813 | Mstep = stringFrag.junctionRestFrame( pInRF[0], pInRF[1], pInRF[2]); |
---|
814 | MtoRF.rotbst( Mstep ); |
---|
815 | } while (iter < 3 || (Mstep.deviation() > CONVJNREST |
---|
816 | && iter < NTRYJNREST) ); |
---|
817 | |
---|
818 | // Store final boost and rest-frame (weighted) momenta. |
---|
819 | if (iJun == 0) { |
---|
820 | MtoJRF = MtoRF; |
---|
821 | for (int i = 0; i < 3; ++i) pInJRF[i] = pInRF[i]; |
---|
822 | } else { |
---|
823 | MtoARF = MtoRF; |
---|
824 | for (int i = 0; i < 3; ++i) pInARF[i] = pInRF[i]; |
---|
825 | } |
---|
826 | } |
---|
827 | |
---|
828 | // Opposite operations: boost from JRF/ARF to original system. |
---|
829 | RotBstMatrix MfromJRF = MtoJRF; |
---|
830 | MfromJRF.invert(); |
---|
831 | RotBstMatrix MfromARF = MtoARF; |
---|
832 | MfromARF.invert(); |
---|
833 | |
---|
834 | // Velocity vectors of junctions and momentum of legs in lab frame. |
---|
835 | Vec4 vJun(0., 0., 0., 1.); |
---|
836 | vJun.rotbst(MfromJRF); |
---|
837 | Vec4 vAnti(0., 0., 0., 1.); |
---|
838 | vAnti.rotbst(MfromARF); |
---|
839 | Vec4 pLabJ[3], pLabA[3]; |
---|
840 | for (int i = 0; i < 3; ++i) { |
---|
841 | pLabJ[i] = pInJRF[i]; |
---|
842 | pLabJ[i].rotbst(MfromJRF); |
---|
843 | pLabA[i] = pInARF[i]; |
---|
844 | pLabA[i].rotbst(MfromARF); |
---|
845 | } |
---|
846 | |
---|
847 | // Calculate Lambda-measure length of three possible topologies. |
---|
848 | double vJvA = vJun * vAnti; |
---|
849 | double vJvAe2y = vJvA + sqrt(vJvA*vJvA - 1.); |
---|
850 | double LambdaJA = (2. * pInJRF[0].e()) * (2. * pInJRF[1].e()) |
---|
851 | * (2. * pInARF[0].e()) * (2. * pInARF[1].e()) * vJvAe2y; |
---|
852 | double Lambda00 = (2. * pLabJ[0] * pLabA[0]) |
---|
853 | * (2. * pLabJ[1] * pLabA[1]); |
---|
854 | double Lambda01 = (2. * pLabJ[0] * pLabA[1]) |
---|
855 | * (2. * pLabJ[1] * pLabA[0]); |
---|
856 | |
---|
857 | // Case when either topology without junctions is the shorter one. |
---|
858 | if (LambdaJA > min( Lambda00, Lambda01)) { |
---|
859 | vector<int>& iAntiMatch0 = (Lambda00 < Lambda01) |
---|
860 | ? iAntiLeg0 : iAntiLeg1; |
---|
861 | vector<int>& iAntiMatch1 = (Lambda00 < Lambda01) |
---|
862 | ? iAntiLeg1 : iAntiLeg0; |
---|
863 | |
---|
864 | // Define two quark-antiquark strings. |
---|
865 | iPartonJun.resize(0); |
---|
866 | for (int i = int(iJunLeg0.size()) - 1; i > 0; --i) |
---|
867 | iPartonJun.push_back( iJunLeg0[i] ); |
---|
868 | for (int i = 1; i < int(iAntiMatch0.size()); ++i) |
---|
869 | iPartonJun.push_back( iAntiMatch0[i] ); |
---|
870 | iPartonAntiJun.resize(0); |
---|
871 | for (int i = int(iJunLeg1.size()) - 1; i > 0; --i) |
---|
872 | iPartonAntiJun.push_back( iJunLeg1[i] ); |
---|
873 | for (int i = 1; i < int(iAntiMatch1.size()); ++i) |
---|
874 | iPartonAntiJun.push_back( iAntiMatch1[i] ); |
---|
875 | |
---|
876 | // Match up the colours where the strings are joined. |
---|
877 | int iColJoin = iJunLeg0[1]; |
---|
878 | int iAcolJoin = iAntiMatch0[1]; |
---|
879 | event[iAcolJoin].acol( event[iColJoin].col() ); |
---|
880 | iColJoin = iJunLeg1[1]; |
---|
881 | iAcolJoin = iAntiMatch1[1]; |
---|
882 | event[iAcolJoin].acol( event[iColJoin].col() ); |
---|
883 | |
---|
884 | // Remove junctions from their list. Done. |
---|
885 | event.eraseJunction( max(identJun, identAnti) - 1); |
---|
886 | event.eraseJunction( min(identJun, identAnti) - 1); |
---|
887 | return true; |
---|
888 | } |
---|
889 | |
---|
890 | // Case where junction and antijunction to be separated. |
---|
891 | // Shuffle (p+/p-) momentum of order <mThad> between systems, |
---|
892 | // times 2/3 for 120 degree in JRF, times 1/2 for two legs, |
---|
893 | // but not more than half of what nearest parton carries. |
---|
894 | double eShift = MTHAD / (3. * sqrt(vJvAe2y)); |
---|
895 | double fracJ0 = min(0.5, eShift / pInJRF[0].e()); |
---|
896 | double fracJ1 = min(0.5, eShift / pInJRF[0].e()); |
---|
897 | Vec4 pFromJun = fracJ0 * pJunLeg0 + fracJ1 * pJunLeg1; |
---|
898 | double fracA0 = min(0.5, eShift / pInARF[0].e()); |
---|
899 | double fracA1 = min(0.5, eShift / pInARF[0].e()); |
---|
900 | Vec4 pFromAnti = fracA0 * pAntiLeg0 + fracA1 * pAntiLeg1; |
---|
901 | |
---|
902 | // Pick a new quark at random; for simplicity no diquarks. |
---|
903 | int idQ = flavSel.pickLightQ(); |
---|
904 | |
---|
905 | // Copy junction partons with scaled-down momenta and update legs. |
---|
906 | int mother1 = min(iJunLeg0[1], iJunLeg1[1]); |
---|
907 | int mother2 = max(iJunLeg0[1], iJunLeg1[1]); |
---|
908 | int iNew1 = event.copy(iJunLeg0[1], 76); |
---|
909 | event[iNew1].rescale5(1. - fracJ0); |
---|
910 | iJunLeg0[1] = iNew1; |
---|
911 | int iNew2 = event.copy(iJunLeg1[1], 76); |
---|
912 | event[iNew2].rescale5(1. - fracJ1); |
---|
913 | iJunLeg1[1] = iNew2; |
---|
914 | |
---|
915 | // Update junction colour and store quark with antijunction momentum. |
---|
916 | // Store history as 2 -> 3 step for consistency. |
---|
917 | int colQ = event.nextColTag(); |
---|
918 | event.endColJunction(identJun - 1, legJun[0], colQ); |
---|
919 | int iNewJ = event.append( idQ, 76, mother1, mother2, 0, 0, |
---|
920 | colQ, 0, pFromAnti, pFromAnti.mCalc() ); |
---|
921 | event[mother1].daughters( iNew1, iNewJ); |
---|
922 | event[mother2].daughters( iNew1, iNewJ); |
---|
923 | event[iNew1].mothers( mother1, mother2); |
---|
924 | event[iNew2].mothers( mother1, mother2); |
---|
925 | |
---|
926 | // Copy anti junction partons with scaled-down momenta and update legs. |
---|
927 | mother1 = min(iAntiLeg0[1], iAntiLeg1[1]); |
---|
928 | mother2 = max(iAntiLeg0[1], iAntiLeg1[1]); |
---|
929 | iNew1 = event.copy(iAntiLeg0[1], 76); |
---|
930 | event[iNew1].rescale5(1. - fracA0); |
---|
931 | iAntiLeg0[1] = iNew1; |
---|
932 | iNew2 = event.copy(iAntiLeg1[1], 76); |
---|
933 | event[iNew2].rescale5(1. - fracA1); |
---|
934 | iAntiLeg1[1] = iNew2; |
---|
935 | |
---|
936 | // Update antijunction anticolour and store antiquark with junction |
---|
937 | // momentum. Store history as 2 -> 3 step for consistency. |
---|
938 | int acolQ = event.nextColTag(); |
---|
939 | event.endColJunction(identAnti - 1, legAnti[0], acolQ); |
---|
940 | int iNewA = event.append( -idQ, 76, mother1, mother2, 0, 0, |
---|
941 | 0, acolQ, pFromJun, pFromJun.mCalc() ); |
---|
942 | event[mother1].daughters( iNew1, iNewA); |
---|
943 | event[mother2].daughters( iNew1, iNewA); |
---|
944 | event[iNew1].mothers( mother1, mother2); |
---|
945 | event[iNew2].mothers( mother1, mother2); |
---|
946 | |
---|
947 | // Bookkeep new quark and antiquark on third legs. |
---|
948 | if (legJun[0] == 0) iJunLegA[1] = iNewJ; |
---|
949 | else if (legJun[0] == 1) iJunLegB[1] = iNewJ; |
---|
950 | else iJunLegC[1] = iNewJ; |
---|
951 | if (legAnti[0] == 0) iAntiLegA[1] = iNewA; |
---|
952 | else if (legAnti[0] == 1) iAntiLegB[1] = iNewA; |
---|
953 | else iAntiLegC[1] = iNewA; |
---|
954 | |
---|
955 | // Done with splitting junction from antijunction. |
---|
956 | } |
---|
957 | |
---|
958 | // Put together new junction parton list. |
---|
959 | iPartonJun.resize(0); |
---|
960 | for (int i = 0; i < int(iJunLegA.size()); ++i) |
---|
961 | iPartonJun.push_back( iJunLegA[i] ); |
---|
962 | for (int i = 0; i < int(iJunLegB.size()); ++i) |
---|
963 | iPartonJun.push_back( iJunLegB[i] ); |
---|
964 | for (int i = 0; i < int(iJunLegC.size()); ++i) |
---|
965 | iPartonJun.push_back( iJunLegC[i] ); |
---|
966 | |
---|
967 | // Put together new antijunction parton list. |
---|
968 | iPartonAntiJun.resize(0); |
---|
969 | for (int i = 0; i < int(iAntiLegA.size()); ++i) |
---|
970 | iPartonAntiJun.push_back( iAntiLegA[i] ); |
---|
971 | for (int i = 0; i < int(iAntiLegB.size()); ++i) |
---|
972 | iPartonAntiJun.push_back( iAntiLegB[i] ); |
---|
973 | for (int i = 0; i < int(iAntiLegC.size()); ++i) |
---|
974 | iPartonAntiJun.push_back( iAntiLegC[i] ); |
---|
975 | |
---|
976 | // Now the two junction systems are separated and can be stored. |
---|
977 | return true; |
---|
978 | |
---|
979 | } |
---|
980 | |
---|
981 | //========================================================================== |
---|
982 | |
---|
983 | } // end namespace Pythia8 |
---|
984 | |
---|