1 | // SigmaLeftRightSym.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 |
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7 | // left-right-symmetry simulation classes. |
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8 | |
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9 | #include "SigmaLeftRightSym.h" |
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10 | |
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11 | namespace Pythia8 { |
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12 | |
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13 | //========================================================================== |
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14 | |
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15 | // Sigma1ffbar2ZRight class. |
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16 | // Cross section for f fbar -> Z_R^0 (righthanded gauge boson). |
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17 | |
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18 | //-------------------------------------------------------------------------- |
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19 | |
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20 | // Initialize process. |
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21 | |
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22 | void Sigma1ffbar2ZRight::initProc() { |
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23 | |
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24 | // Store Z_R mass and width for propagator. |
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25 | idZR = 9900023; |
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26 | mRes = particleDataPtr->m0(idZR); |
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27 | GammaRes = particleDataPtr->mWidth(idZR); |
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28 | m2Res = mRes*mRes; |
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29 | GamMRat = GammaRes / mRes; |
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30 | sin2tW = couplingsPtr->sin2thetaW(); |
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31 | |
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32 | // Set pointer to particle properties and decay table. |
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33 | ZRPtr = particleDataPtr->particleDataEntryPtr(idZR); |
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34 | |
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35 | } |
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36 | |
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37 | //-------------------------------------------------------------------------- |
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38 | |
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39 | // Evaluate sigmaHat(sHat), part independent of incoming flavour. |
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40 | |
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41 | void Sigma1ffbar2ZRight::sigmaKin() { |
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42 | |
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43 | // Set up Breit-Wigner. Width out only includes open channels. |
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44 | double sigBW = 12. * M_PI/ ( pow2(sH - m2Res) + pow2(sH * GamMRat) ); |
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45 | double widthOut = ZRPtr->resWidthOpen(idZR, mH); |
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46 | |
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47 | // Prefactor for incoming widths. Combine. Done. |
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48 | double preFac = alpEM * mH / ( 48. * sin2tW * (1. - sin2tW) |
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49 | * (1. - 2. * sin2tW) ); |
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50 | sigma0 = preFac * sigBW * widthOut; |
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51 | |
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52 | } |
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53 | |
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54 | //-------------------------------------------------------------------------- |
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55 | |
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56 | // Evaluate sigmaHat(sHat), including incoming flavour dependence. |
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57 | |
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58 | double Sigma1ffbar2ZRight::sigmaHat() { |
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59 | |
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60 | // Vector and axial couplings of incoming fermion pair. |
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61 | int idAbs = abs(id1); |
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62 | double af = 0.; |
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63 | double vf = 0.; |
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64 | if (idAbs < 9 && idAbs%2 == 1) { |
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65 | af = -1. + 2. * sin2tW; |
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66 | vf = -1. + 4. * sin2tW / 3.; |
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67 | } else if (idAbs < 9) { |
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68 | af = 1. - 2. * sin2tW; |
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69 | vf = 1. - 8. * sin2tW / 3.; |
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70 | } else if (idAbs < 19 && idAbs%2 == 1) { |
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71 | af = -1. + 2. * sin2tW; |
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72 | vf = -1. + 4. * sin2tW; |
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73 | } |
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74 | |
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75 | // Colour factor. Answer. |
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76 | double sigma = (vf*vf + af*af) * sigma0; |
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77 | if (idAbs < 9) sigma /= 3.; |
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78 | return sigma; |
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79 | |
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80 | } |
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81 | |
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82 | //-------------------------------------------------------------------------- |
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83 | |
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84 | // Select identity, colour and anticolour. |
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85 | |
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86 | void Sigma1ffbar2ZRight::setIdColAcol() { |
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87 | |
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88 | // Flavours trivial. |
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89 | setId( id1, id2, idZR); |
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90 | |
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91 | // Colour flow topologies. Swap when antiquarks. |
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92 | if (abs(id1) < 9) setColAcol( 1, 0, 0, 1, 0, 0); |
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93 | else setColAcol( 0, 0, 0, 0, 0, 0); |
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94 | if (id1 < 0) swapColAcol(); |
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95 | |
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96 | } |
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97 | |
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98 | //-------------------------------------------------------------------------- |
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99 | |
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100 | // Evaluate weight for Z_R decay angle. |
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101 | |
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102 | double Sigma1ffbar2ZRight::weightDecay( Event& process, int iResBeg, |
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103 | int iResEnd) { |
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104 | |
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105 | // Identity of mother of decaying reseonance(s). |
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106 | int idMother = process[process[iResBeg].mother1()].idAbs(); |
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107 | |
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108 | // For top decay hand over to standard routine. |
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109 | if (idMother == 6) |
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110 | return weightTopDecay( process, iResBeg, iResEnd); |
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111 | |
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112 | // Z_R should sit in entry 5. |
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113 | if (iResBeg != 5 || iResEnd != 5) return 1.; |
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114 | |
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115 | // Couplings for in- and out-flavours. |
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116 | double ai, vi, af, vf; |
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117 | int idInAbs = process[3].idAbs(); |
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118 | if (idInAbs < 9 && idInAbs%2 == 1) { |
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119 | ai = -1. + 2. * sin2tW; |
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120 | vi = -1. + 4. * sin2tW / 3.; |
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121 | } else if (idInAbs < 9) { |
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122 | ai = 1. - 2. * sin2tW; |
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123 | vi = 1. - 8. * sin2tW / 3.; |
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124 | } else { |
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125 | ai = -1. + 2. * sin2tW; |
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126 | vi = -1. + 4. * sin2tW; |
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127 | } |
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128 | int idOutAbs = process[6].idAbs(); |
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129 | if (idOutAbs < 9 && idOutAbs%2 == 1) { |
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130 | af = -1. + 2. * sin2tW; |
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131 | vf = -1. + 4. * sin2tW / 3.; |
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132 | } else if (idOutAbs < 9) { |
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133 | af = 1. - 2. * sin2tW; |
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134 | vf = 1. - 8. * sin2tW / 3.; |
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135 | } else { |
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136 | af = -1. + 2. * sin2tW; |
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137 | vf = -1. + 4. * sin2tW; |
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138 | } |
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139 | |
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140 | // Phase space factors. Reconstruct decay angle. |
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141 | double mr1 = pow2(process[6].m()) / sH; |
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142 | double mr2 = pow2(process[7].m()) / sH; |
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143 | double betaf = sqrtpos( pow2(1. - mr1 - mr2) - 4. * mr1 * mr2); |
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144 | double cosThe = (process[3].p() - process[4].p()) |
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145 | * (process[7].p() - process[6].p()) / (sH * betaf); |
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146 | |
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147 | // Angular weight and its maximum. |
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148 | double wt1 = (vi*vi + ai*ai) * (vf*vf + af*af * betaf*betaf); |
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149 | double wt2 = (1. - betaf*betaf) * (vi*vi + ai*ai) * vf*vf; |
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150 | double wt3 = betaf * 4. * vi * ai * vf * af; |
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151 | if (process[3].id() * process[6].id() < 0) wt3 = -wt3; |
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152 | double wt = wt1 * (1. + cosThe*cosThe) + wt2 * (1. - cosThe*cosThe) |
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153 | + 2. * wt3 * cosThe; |
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154 | double wtMax = 2. * (wt1 + abs(wt3)); |
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155 | |
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156 | // Done. |
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157 | return wt / wtMax; |
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158 | |
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159 | } |
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160 | |
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161 | //========================================================================== |
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162 | |
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163 | // Sigma1ffbar2WRight class. |
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164 | // Cross section for f fbar' -> W_R^+- (righthanded gauge boson). |
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165 | |
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166 | //-------------------------------------------------------------------------- |
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167 | |
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168 | // Initialize process. |
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169 | |
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170 | void Sigma1ffbar2WRight::initProc() { |
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171 | |
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172 | // Store W_R^+- mass and width for propagator. |
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173 | idWR = 9900024; |
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174 | mRes = particleDataPtr->m0(idWR); |
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175 | GammaRes = particleDataPtr->mWidth(idWR); |
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176 | m2Res = mRes*mRes; |
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177 | GamMRat = GammaRes / mRes; |
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178 | thetaWRat = 1. / (12. * couplingsPtr->sin2thetaW()); |
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179 | |
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180 | // Set pointer to particle properties and decay table. |
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181 | particlePtr = particleDataPtr->particleDataEntryPtr(idWR); |
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182 | |
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183 | } |
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184 | |
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185 | //-------------------------------------------------------------------------- |
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186 | |
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187 | // Evaluate sigmaHat(sHat), part independent of incoming flavour. |
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188 | |
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189 | void Sigma1ffbar2WRight::sigmaKin() { |
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190 | |
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191 | // Common coupling factors. |
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192 | double colQ = 3. * (1. + alpS / M_PI); |
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193 | |
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194 | // Reset quantities to sum. Declare variables inside loop. |
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195 | double widOutPos = 0.; |
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196 | double widOutNeg = 0.; |
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197 | int id1Now, id2Now, id1Abs, id2Abs, id1Neg, id2Neg, onMode; |
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198 | double widNow, widSecPos, widSecNeg, mf1, mf2, mr1, mr2, kinFac; |
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199 | |
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200 | // Loop over all W_R^+- decay channels. |
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201 | for (int i = 0; i < particlePtr->sizeChannels(); ++i) { |
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202 | id1Now = particlePtr->channel(i).product(0); |
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203 | id2Now = particlePtr->channel(i).product(1); |
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204 | id1Abs = abs(id1Now); |
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205 | id2Abs = abs(id2Now); |
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206 | |
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207 | // Check that above threshold. Phase space. |
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208 | mf1 = particleDataPtr->m0(id1Abs); |
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209 | mf2 = particleDataPtr->m0(id2Abs); |
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210 | if (mH > mf1 + mf2 + MASSMARGIN) { |
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211 | mr1 = pow2(mf1 / mH); |
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212 | mr2 = pow2(mf2 / mH); |
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213 | kinFac = (1. - 0.5 * (mr1 + mr2) - 0.5 * pow2(mr1 - mr2)) |
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214 | * sqrtpos( pow2(1. - mr1 - mr2) - 4. * mr1 * mr2 ); |
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215 | |
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216 | // Combine kinematics with colour factor and CKM couplings. |
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217 | widNow = kinFac; |
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218 | if (id1Abs < 9) widNow *= colQ * couplingsPtr->V2CKMid(id1Abs, id2Abs); |
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219 | |
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220 | // Secondary width from top and righthanded neutrino decay. |
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221 | id1Neg = (id1Abs < 19) ? -id1Now : id1Abs; |
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222 | id2Neg = (id2Abs < 19) ? -id2Now : id2Abs; |
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223 | widSecPos = particleDataPtr->resOpenFrac(id1Now, id2Now); |
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224 | widSecNeg = particleDataPtr->resOpenFrac(id1Neg, id2Neg); |
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225 | |
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226 | // Add weight for channels on for all, W_R^+ and W_R^-, respectively. |
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227 | onMode = particlePtr->channel(i).onMode(); |
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228 | if (onMode == 1 || onMode == 2) widOutPos += widNow * widSecPos; |
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229 | if (onMode == 1 || onMode == 3) widOutNeg += widNow * widSecNeg; |
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230 | |
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231 | // End loop over fermions. |
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232 | } |
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233 | } |
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234 | |
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235 | // Set up Breit-Wigner. Cross section for W_R^+ and W_R^- separately. |
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236 | double sigBW = 12. * M_PI * pow2(alpEM * thetaWRat) * sH |
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237 | / ( pow2(sH - m2Res) + pow2(sH * GamMRat) ); |
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238 | sigma0Pos = sigBW * widOutPos; |
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239 | sigma0Neg = sigBW * widOutNeg; |
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240 | |
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241 | } |
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242 | |
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243 | //-------------------------------------------------------------------------- |
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244 | |
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245 | // Evaluate sigmaHat(sHat), including incoming flavour dependence. |
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246 | |
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247 | double Sigma1ffbar2WRight::sigmaHat() { |
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248 | |
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249 | // Secondary width for W_R^+ or W_R^-. CKM and colour factors. |
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250 | int idUp = (abs(id1)%2 == 0) ? id1 : id2; |
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251 | double sigma = (idUp > 0) ? sigma0Pos : sigma0Neg; |
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252 | if (abs(id1) < 9) sigma *= couplingsPtr->V2CKMid(abs(id1), abs(id2)) / 3.; |
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253 | |
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254 | // Answer. |
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255 | return sigma; |
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256 | |
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257 | } |
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258 | |
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259 | //-------------------------------------------------------------------------- |
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260 | |
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261 | // Select identity, colour and anticolour. |
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262 | |
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263 | void Sigma1ffbar2WRight::setIdColAcol() { |
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264 | |
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265 | // Sign of outgoing W_R. |
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266 | int sign = (abs(id1)%2 == 0) ? 1 : -1; |
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267 | if (id1 < 0) sign = -sign; |
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268 | setId( id1, id2, idWR * sign); |
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269 | |
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270 | // Colour flow topologies. Swap when antiquarks. |
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271 | if (abs(id1) < 9) setColAcol( 1, 0, 0, 1, 0, 0); |
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272 | else setColAcol( 0, 0, 0, 0, 0, 0); |
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273 | if (id1 < 0) swapColAcol(); |
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274 | |
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275 | } |
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276 | |
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277 | //-------------------------------------------------------------------------- |
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278 | |
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279 | // Evaluate weight for W_R decay angle. |
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280 | |
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281 | double Sigma1ffbar2WRight::weightDecay( Event& process, int iResBeg, |
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282 | int iResEnd) { |
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283 | |
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284 | // Identity of mother of decaying reseonance(s). |
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285 | int idMother = process[process[iResBeg].mother1()].idAbs(); |
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286 | |
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287 | // For top decay hand over to standard routine. |
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288 | if (idMother == 6) |
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289 | return weightTopDecay( process, iResBeg, iResEnd); |
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290 | |
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291 | // W_R should sit in entry 5. |
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292 | if (iResBeg != 5 || iResEnd != 5) return 1.; |
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293 | |
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294 | // Phase space factors. |
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295 | double mr1 = pow2(process[6].m()) / sH; |
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296 | double mr2 = pow2(process[7].m()) / sH; |
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297 | double betaf = sqrtpos( pow2(1. - mr1 - mr2) - 4. * mr1 * mr2); |
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298 | |
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299 | // Sign of asymmetry. |
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300 | double eps = (process[3].id() * process[6].id() > 0) ? 1. : -1.; |
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301 | |
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302 | // Reconstruct decay angle and weight for it. |
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303 | double cosThe = (process[3].p() - process[4].p()) |
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304 | * (process[7].p() - process[6].p()) / (sH * betaf); |
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305 | double wtMax = 4.; |
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306 | double wt = pow2(1. + betaf * eps * cosThe) - pow2(mr1 - mr2); |
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307 | |
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308 | // Done. |
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309 | return (wt / wtMax); |
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310 | |
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311 | } |
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312 | |
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313 | //========================================================================== |
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314 | |
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315 | // Sigma1ll2Hchgchg class. |
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316 | // Cross section for l l -> H_L^++-- or H_R^++-- (doubly charged Higgs). |
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317 | |
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318 | //-------------------------------------------------------------------------- |
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319 | |
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320 | // Initialize process. |
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321 | |
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322 | void Sigma1ll2Hchgchg::initProc() { |
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323 | |
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324 | // Set process properties: H_L^++-- or H_R^++--. |
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325 | if (leftRight == 1) { |
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326 | idHLR = 9900041; |
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327 | codeSave = 3121; |
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328 | nameSave = "l l -> H_L^++--"; |
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329 | } else { |
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330 | idHLR = 9900042; |
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331 | codeSave = 3141; |
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332 | nameSave = "l l -> H_R^++--"; |
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333 | } |
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334 | |
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335 | // Read in Yukawa matrix for couplings to a lepton pair. |
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336 | yukawa[1][1] = settingsPtr->parm("LeftRightSymmmetry:coupHee"); |
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337 | yukawa[2][1] = settingsPtr->parm("LeftRightSymmmetry:coupHmue"); |
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338 | yukawa[2][2] = settingsPtr->parm("LeftRightSymmmetry:coupHmumu"); |
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339 | yukawa[3][1] = settingsPtr->parm("LeftRightSymmmetry:coupHtaue"); |
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340 | yukawa[3][2] = settingsPtr->parm("LeftRightSymmmetry:coupHtaumu"); |
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341 | yukawa[3][3] = settingsPtr->parm("LeftRightSymmmetry:coupHtautau"); |
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342 | |
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343 | // Store H_L/R mass and width for propagator. |
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344 | mRes = particleDataPtr->m0(idHLR); |
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345 | GammaRes = particleDataPtr->mWidth(idHLR); |
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346 | m2Res = mRes*mRes; |
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347 | GamMRat = GammaRes / mRes; |
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348 | |
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349 | // Set pointer to particle properties and decay table. |
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350 | particlePtr = particleDataPtr->particleDataEntryPtr(idHLR); |
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351 | |
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352 | } |
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353 | |
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354 | //-------------------------------------------------------------------------- |
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355 | |
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356 | // Evaluate sigmaHat(sHat), including incoming flavour dependence. |
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357 | |
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358 | double Sigma1ll2Hchgchg::sigmaHat() { |
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359 | |
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360 | // Initial state must consist of two identical-sign leptons. |
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361 | if (id1 * id2 < 0) return 0.; |
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362 | int id1Abs = abs(id1); |
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363 | int id2Abs = abs(id2); |
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364 | if (id1Abs != 11 && id1Abs != 13 && id1Abs != 15) return 0.; |
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365 | if (id2Abs != 11 && id2Abs != 13 && id2Abs != 15) return 0.; |
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366 | |
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367 | // Set up Breit-Wigner, inwidth and outwidth. |
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368 | double sigBW = 8. * M_PI / ( pow2(sH - m2Res) + pow2(sH * GamMRat) ); |
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369 | double widIn = pow2(yukawa[(id1Abs-9)/2][(id2Abs-9)/2]) |
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370 | * mH / (8. * M_PI); |
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371 | int idSgn = (id1 < 0) ? idHLR : -idHLR; |
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372 | double widOut = particlePtr->resWidthOpen( idSgn, mH); |
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373 | |
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374 | // Answer. |
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375 | return widIn * sigBW * widOut; |
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376 | |
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377 | } |
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378 | |
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379 | //-------------------------------------------------------------------------- |
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380 | |
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381 | // Select identity, colour and anticolour. |
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382 | |
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383 | void Sigma1ll2Hchgchg::setIdColAcol() { |
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384 | |
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385 | // Sign of outgoing H_L/R. |
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386 | int idSgn = (id1 < 0) ? idHLR : -idHLR; |
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387 | setId( id1, id2, idSgn); |
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388 | |
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389 | // No colours whatsoever. |
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390 | setColAcol( 0, 0, 0, 0, 0, 0); |
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391 | |
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392 | } |
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393 | |
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394 | //-------------------------------------------------------------------------- |
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395 | |
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396 | // Evaluate weight for H_L/R sequential decay angles. |
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397 | |
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398 | double Sigma1ll2Hchgchg::weightDecay( Event& process, int iResBeg, |
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399 | int iResEnd) { |
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400 | |
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401 | // Identity of mother of decaying reseonance(s). |
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402 | int idMother = process[process[iResBeg].mother1()].idAbs(); |
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403 | |
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404 | // For top decay hand over to standard routine. |
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405 | if (idMother == 6) |
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406 | return weightTopDecay( process, iResBeg, iResEnd); |
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407 | |
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408 | // Else isotropic decay. |
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409 | return 1.; |
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410 | |
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411 | } |
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412 | |
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413 | //========================================================================== |
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414 | |
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415 | // Sigma2lgm2Hchgchgl class. |
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416 | // Cross section for l gamma -> H_L^++-- l or H_R^++-- l |
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417 | // (doubly charged Higgs). |
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418 | |
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419 | //-------------------------------------------------------------------------- |
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420 | |
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421 | // Initialize process. |
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422 | |
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423 | void Sigma2lgm2Hchgchgl::initProc() { |
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424 | |
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425 | // Set process properties: H_L^++-- or H_R^++-- and e/mu/tau. |
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426 | idHLR = (leftRight == 1) ? 9900041 : 9900042; |
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427 | codeSave = (leftRight == 1) ? 3122 : 3142; |
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428 | if (idLep == 13) codeSave += 2; |
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429 | if (idLep == 15) codeSave += 4; |
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430 | if (codeSave == 3122) nameSave = "l^+- gamma -> H_L^++-- e^-+"; |
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431 | else if (codeSave == 3123) nameSave = "l^+- gamma -> H_L^++-- mu^-+"; |
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432 | else if (codeSave == 3124) nameSave = "l^+- gamma -> H_L^++-- tau^-+"; |
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433 | else if (codeSave == 3142) nameSave = "l^+- gamma -> H_R^++-- e^-+"; |
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434 | else if (codeSave == 3143) nameSave = "l^+- gamma -> H_R^++-- mu^-+"; |
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435 | else nameSave = "l^+- gamma -> H_R^++-- tau^-+"; |
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436 | |
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437 | // Read in relevantYukawa matrix for couplings to a lepton pair. |
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438 | if (idLep == 11) { |
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439 | yukawa[1] = settingsPtr->parm("LeftRightSymmmetry:coupHee"); |
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440 | yukawa[2] = settingsPtr->parm("LeftRightSymmmetry:coupHmue"); |
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441 | yukawa[3] = settingsPtr->parm("LeftRightSymmmetry:coupHtaue"); |
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442 | } else if (idLep == 13) { |
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443 | yukawa[1] = settingsPtr->parm("LeftRightSymmmetry:coupHmue"); |
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444 | yukawa[2] = settingsPtr->parm("LeftRightSymmmetry:coupHmumu"); |
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445 | yukawa[3] = settingsPtr->parm("LeftRightSymmmetry:coupHtaumu"); |
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446 | } else { |
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447 | yukawa[1] = settingsPtr->parm("LeftRightSymmmetry:coupHtaue"); |
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448 | yukawa[2] = settingsPtr->parm("LeftRightSymmmetry:coupHtaumu"); |
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449 | yukawa[3] = settingsPtr->parm("LeftRightSymmmetry:coupHtautau"); |
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450 | } |
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451 | |
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452 | // Secondary open width fractions. |
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453 | openFracPos = particleDataPtr->resOpenFrac( idHLR); |
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454 | openFracNeg = particleDataPtr->resOpenFrac(-idHLR); |
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455 | |
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456 | } |
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457 | |
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458 | //-------------------------------------------------------------------------- |
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459 | |
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460 | // Evaluate sigmaHat(sHat), including incoming flavour dependence. |
---|
461 | |
---|
462 | double Sigma2lgm2Hchgchgl::sigmaHat() { |
---|
463 | |
---|
464 | // Initial state must consist of a lepton and a photon. |
---|
465 | int idIn = (id2 == 22) ? id1 : id2; |
---|
466 | int idInAbs = abs(idIn); |
---|
467 | if (idInAbs != 11 && idInAbs != 13 && idInAbs != 15) return 0.; |
---|
468 | |
---|
469 | // Incoming squared lepton mass. |
---|
470 | double s1 = pow2( particleDataPtr->m0(idInAbs) ); |
---|
471 | |
---|
472 | // Kinematical expressions. |
---|
473 | double smm1 = 8. * (sH + tH - s3) * (sH + tH - 2. * s3 - s1 - s4) |
---|
474 | / pow2(uH - s3); |
---|
475 | double smm2 = 2. * ( (2. * s3 - 3. * s1) * s4 + (s1 - 2. * s4) * tH |
---|
476 | - (tH - s4) * sH ) / pow2(tH - s4); |
---|
477 | double smm3 = 2. * ( (2. * s3 - 3. * s4 + tH) * s1 |
---|
478 | - (2. * s1 - s4 + tH) * sH ) / pow2(sH - s1); |
---|
479 | double smm12 = 4. * ( (2. * s1 - s4 - 2. * s3 + tH) * sH |
---|
480 | + (tH - 3. * s3 - 3. * s4) * tH + (2. * s3 - 2. * s1 |
---|
481 | + 3. * s4) * s3 ) / ( (uH - s3) * (tH - s4) ); |
---|
482 | double smm13 = -4. * ( (tH + s1 - 2. * s4) * tH - (s3 + 3. * s1 - 2. * s4) |
---|
483 | * s3 + (s3 + 3. * s1 + tH) * sH - pow2(tH - s3 + sH) ) |
---|
484 | / ( (uH - s3) * (sH - s1) ); |
---|
485 | double smm23 = -4. * ( (s1 - s4 + s3) * tH - s3*s3 + s3 * (s1 + s4) |
---|
486 | - 3. * s1 * s4 - (s1 - s4 - s3 + tH) * sH) |
---|
487 | / ( (sH - s1) * (tH - s4) ); |
---|
488 | double sigma = alpEM * pow2(sH / (sH - s1) ) * (smm1 + smm2 + smm3 |
---|
489 | + smm12 + smm13 + smm23) / (4. * sH2); |
---|
490 | |
---|
491 | // Lepton Yukawa and secondary widths. |
---|
492 | sigma *= pow2(yukawa[(idInAbs-9)/2]); |
---|
493 | sigma *= (idIn < 0) ? openFracPos : openFracNeg; |
---|
494 | |
---|
495 | // Answer. |
---|
496 | return sigma; |
---|
497 | |
---|
498 | } |
---|
499 | |
---|
500 | //-------------------------------------------------------------------------- |
---|
501 | |
---|
502 | // Select identity, colour and anticolour. |
---|
503 | |
---|
504 | void Sigma2lgm2Hchgchgl::setIdColAcol() { |
---|
505 | |
---|
506 | // Sign of outgoing H_L/R. |
---|
507 | int idIn = (id2 == 22) ? id1 : id2; |
---|
508 | int idSgn = (idIn < 0) ? idHLR : -idHLR; |
---|
509 | int idOut = (idIn < 0) ? idLep : -idLep; |
---|
510 | setId( id1, id2, idSgn, idOut); |
---|
511 | |
---|
512 | // tHat is defined between incoming lepton and outgoing Higgs. |
---|
513 | if (id1 == 22) swapTU = true; |
---|
514 | |
---|
515 | // No colours whatsoever. |
---|
516 | setColAcol( 0, 0, 0, 0, 0, 0, 0, 0); |
---|
517 | |
---|
518 | } |
---|
519 | |
---|
520 | //-------------------------------------------------------------------------- |
---|
521 | |
---|
522 | // Evaluate weight for H_L/R sequential decay angles. |
---|
523 | |
---|
524 | double Sigma2lgm2Hchgchgl::weightDecay( Event& process, int iResBeg, |
---|
525 | int iResEnd) { |
---|
526 | |
---|
527 | // Identity of mother of decaying reseonance(s). |
---|
528 | int idMother = process[process[iResBeg].mother1()].idAbs(); |
---|
529 | |
---|
530 | // For top decay hand over to standard routine. |
---|
531 | if (idMother == 6) |
---|
532 | return weightTopDecay( process, iResBeg, iResEnd); |
---|
533 | |
---|
534 | // Else isotropic decay. |
---|
535 | return 1.; |
---|
536 | |
---|
537 | } |
---|
538 | |
---|
539 | //========================================================================== |
---|
540 | |
---|
541 | // Sigma3ff2HchgchgfftWW class. |
---|
542 | // Cross section for f_1 f_2 -> H_(L/R)^++-- f_3 f_4 (W+- W+- fusion). |
---|
543 | |
---|
544 | //-------------------------------------------------------------------------- |
---|
545 | |
---|
546 | // Initialize process. |
---|
547 | |
---|
548 | void Sigma3ff2HchgchgfftWW::initProc() { |
---|
549 | |
---|
550 | // Set process properties: H_L^++-- or H_R^++--. |
---|
551 | if (leftRight == 1) { |
---|
552 | idHLR = 9900041; |
---|
553 | codeSave = 3125; |
---|
554 | nameSave = "f_1 f_2 -> H_L^++-- f_3 f_4 (W+- W+- fusion)"; |
---|
555 | } else { |
---|
556 | idHLR = 9900042; |
---|
557 | codeSave = 3145; |
---|
558 | nameSave = "f_1 f_2 -> H_R^++-- f_3 f_4 (W+- W+- fusion)"; |
---|
559 | } |
---|
560 | |
---|
561 | // Common fixed mass and coupling factor. |
---|
562 | double mW = particleDataPtr->m0(24); |
---|
563 | double mWR = particleDataPtr->m0(9900024); |
---|
564 | mWS = (leftRight == 1) ? pow2(mW) : pow2(mWR); |
---|
565 | double gL = settingsPtr->parm("LeftRightSymmmetry:gL"); |
---|
566 | double gR = settingsPtr->parm("LeftRightSymmmetry:gR"); |
---|
567 | double vL = settingsPtr->parm("LeftRightSymmmetry:vL"); |
---|
568 | prefac = (leftRight == 1) ? pow2(pow4(gL) * vL) |
---|
569 | : 2. * pow2(pow3(gR) * mWR); |
---|
570 | // Secondary open width fractions. |
---|
571 | openFracPos = particleDataPtr->resOpenFrac( idHLR); |
---|
572 | openFracNeg = particleDataPtr->resOpenFrac(-idHLR); |
---|
573 | |
---|
574 | } |
---|
575 | |
---|
576 | //-------------------------------------------------------------------------- |
---|
577 | |
---|
578 | // Evaluate sigmaHat(sHat), part independent of incoming flavour. |
---|
579 | |
---|
580 | void Sigma3ff2HchgchgfftWW::sigmaKin() { |
---|
581 | |
---|
582 | // Required four-vector products. |
---|
583 | double pp12 = 0.5 * sH; |
---|
584 | double pp14 = 0.5 * mH * p4cm.pNeg(); |
---|
585 | double pp15 = 0.5 * mH * p5cm.pNeg(); |
---|
586 | double pp24 = 0.5 * mH * p4cm.pPos(); |
---|
587 | double pp25 = 0.5 * mH * p5cm.pPos(); |
---|
588 | double pp45 = p4cm * p5cm; |
---|
589 | |
---|
590 | // Cross section: kinematics part. Combine with couplings. |
---|
591 | double propT = 1. / ( (2. * pp14 + mWS) * (2. * pp25 + mWS) ); |
---|
592 | double propU = 1. / ( (2. * pp24 + mWS) * (2. * pp15 + mWS) ); |
---|
593 | sigma0TU = prefac * pp12 * pp45 * pow2(propT + propU); |
---|
594 | sigma0T = prefac * pp12 * pp45 * 2. * pow2(propT); |
---|
595 | |
---|
596 | } |
---|
597 | |
---|
598 | //-------------------------------------------------------------------------- |
---|
599 | |
---|
600 | // Evaluate sigmaHat(sHat), including incoming flavour dependence. |
---|
601 | |
---|
602 | double Sigma3ff2HchgchgfftWW::sigmaHat() { |
---|
603 | |
---|
604 | // Do not allow creation of righthanded neutrinos for H_R. |
---|
605 | int id1Abs = abs(id1); |
---|
606 | int id2Abs = abs(id2); |
---|
607 | if ( leftRight == 2 && (id1Abs > 10 || id2Abs > 10) ) return 0.; |
---|
608 | |
---|
609 | // Many flavour combinations not possible because of charge. |
---|
610 | int chg1 = (( id1Abs%2 == 0 && id1 > 0) |
---|
611 | || (id1Abs%2 == 1 && id1 < 0) ) ? 1 : -1; |
---|
612 | int chg2 = (( id2Abs%2 == 0 && id2 > 0) |
---|
613 | || (id2Abs%2 == 1 && id2 < 0) ) ? 1 : -1; |
---|
614 | if (abs(chg1 + chg2) != 2) return 0.; |
---|
615 | |
---|
616 | // Basic cross section. CKM factors for final states. |
---|
617 | double sigma = (id2 == id1 && id1Abs > 10) ? sigma0TU : sigma0T; |
---|
618 | sigma *= couplingsPtr->V2CKMsum(id1Abs) |
---|
619 | * couplingsPtr->V2CKMsum(id2Abs); |
---|
620 | |
---|
621 | // Secondary width for H0. |
---|
622 | sigma *= (chg1 + chg2 == 2) ? openFracPos : openFracNeg; |
---|
623 | |
---|
624 | // Spin-state extra factor 2 per incoming neutrino. |
---|
625 | if (id1Abs == 12 || id1Abs == 14 || id1Abs == 16) sigma *= 2.; |
---|
626 | if (id2Abs == 12 || id2Abs == 14 || id2Abs == 16) sigma *= 2.; |
---|
627 | |
---|
628 | // Answer. |
---|
629 | return sigma; |
---|
630 | |
---|
631 | } |
---|
632 | |
---|
633 | //-------------------------------------------------------------------------- |
---|
634 | |
---|
635 | // Select identity, colour and anticolour. |
---|
636 | |
---|
637 | void Sigma3ff2HchgchgfftWW::setIdColAcol() { |
---|
638 | |
---|
639 | // Pick out-flavours by relative CKM weights. |
---|
640 | int id1Abs = abs(id1); |
---|
641 | int id2Abs = abs(id2); |
---|
642 | id4 = couplingsPtr->V2CKMpick(id1); |
---|
643 | id5 = couplingsPtr->V2CKMpick(id2); |
---|
644 | |
---|
645 | // Find charge of Higgs . |
---|
646 | id3 = (( id1Abs%2 == 0 && id1 > 0) || (id1Abs%2 == 1 && id1 < 0) ) |
---|
647 | ? idHLR : -idHLR; |
---|
648 | setId( id1, id2, id3, id4, id5); |
---|
649 | |
---|
650 | // Colour flow topologies. Swap when antiquarks. |
---|
651 | if (id1Abs < 9 && id2Abs < 9 && id1*id2 > 0) |
---|
652 | setColAcol( 1, 0, 2, 0, 0, 0, 1, 0, 2, 0); |
---|
653 | else if (id1Abs < 9 && id2Abs < 9) |
---|
654 | setColAcol( 1, 0, 0, 2, 0, 0, 1, 0, 0, 2); |
---|
655 | else if (id1Abs < 9) setColAcol( 1, 0, 0, 0, 0, 0, 1, 0, 0, 0); |
---|
656 | else if (id2Abs < 9) setColAcol( 0, 0, 1, 0, 0, 0, 0, 0, 1, 0); |
---|
657 | else setColAcol( 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); |
---|
658 | if ( (id1Abs < 9 && id1 < 0) || (id1Abs > 10 && id2 < 0) ) |
---|
659 | swapColAcol(); |
---|
660 | |
---|
661 | } |
---|
662 | |
---|
663 | //-------------------------------------------------------------------------- |
---|
664 | |
---|
665 | // Evaluate weight for decay angles. |
---|
666 | |
---|
667 | double Sigma3ff2HchgchgfftWW::weightDecay( Event& process, int iResBeg, |
---|
668 | int iResEnd) { |
---|
669 | |
---|
670 | // Identity of mother of decaying reseonance(s). |
---|
671 | int idMother = process[process[iResBeg].mother1()].idAbs(); |
---|
672 | |
---|
673 | // For top decay hand over to standard routine. |
---|
674 | if (idMother == 6) |
---|
675 | return weightTopDecay( process, iResBeg, iResEnd); |
---|
676 | |
---|
677 | // Else done. |
---|
678 | return 1.; |
---|
679 | |
---|
680 | } |
---|
681 | |
---|
682 | //========================================================================== |
---|
683 | |
---|
684 | // Sigma2ffbar2HchgchgHchgchg class. |
---|
685 | // Cross section for f fbar -> H_(L/R)^++ H_(L/R)^-- (doubly charged Higgs). |
---|
686 | |
---|
687 | //-------------------------------------------------------------------------- |
---|
688 | |
---|
689 | // Initialize process. |
---|
690 | |
---|
691 | void Sigma2ffbar2HchgchgHchgchg::initProc() { |
---|
692 | |
---|
693 | // Set process properties: H_L^++ H_L^-- or H_R^++ H_R^--. |
---|
694 | if (leftRight == 1) { |
---|
695 | idHLR = 9900041; |
---|
696 | codeSave = 3126; |
---|
697 | nameSave = "f fbar -> H_L^++ H_L^--"; |
---|
698 | } else { |
---|
699 | idHLR = 9900042; |
---|
700 | codeSave = 3146; |
---|
701 | nameSave = "f fbar -> H_R^++ H_R^--"; |
---|
702 | } |
---|
703 | |
---|
704 | // Read in Yukawa matrix for couplings to a lepton pair. |
---|
705 | yukawa[1][1] = settingsPtr->parm("LeftRightSymmmetry:coupHee"); |
---|
706 | yukawa[2][1] = settingsPtr->parm("LeftRightSymmmetry:coupHmue"); |
---|
707 | yukawa[2][2] = settingsPtr->parm("LeftRightSymmmetry:coupHmumu"); |
---|
708 | yukawa[3][1] = settingsPtr->parm("LeftRightSymmmetry:coupHtaue"); |
---|
709 | yukawa[3][2] = settingsPtr->parm("LeftRightSymmmetry:coupHtaumu"); |
---|
710 | yukawa[3][3] = settingsPtr->parm("LeftRightSymmmetry:coupHtautau"); |
---|
711 | |
---|
712 | // Electroweak parameters. |
---|
713 | mRes = particleDataPtr->m0(23); |
---|
714 | GammaRes = particleDataPtr->mWidth(23); |
---|
715 | m2Res = mRes*mRes; |
---|
716 | GamMRat = GammaRes / mRes; |
---|
717 | sin2tW = couplingsPtr->sin2thetaW(); |
---|
718 | preFac = (1. - 2. * sin2tW) / ( 8. * sin2tW * (1. - sin2tW) ); |
---|
719 | |
---|
720 | // Open fraction from secondary widths. |
---|
721 | openFrac = particleDataPtr->resOpenFrac( idHLR, -idHLR); |
---|
722 | |
---|
723 | } |
---|
724 | |
---|
725 | //-------------------------------------------------------------------------- |
---|
726 | |
---|
727 | // Evaluate sigmaHat(sHat), including incoming flavour dependence. |
---|
728 | |
---|
729 | double Sigma2ffbar2HchgchgHchgchg::sigmaHat() { |
---|
730 | |
---|
731 | // Electroweak couplings to gamma^*/Z^0. |
---|
732 | int idAbs = abs(id1); |
---|
733 | double ei = couplingsPtr->ef(idAbs); |
---|
734 | double vi = couplingsPtr->vf(idAbs); |
---|
735 | double ai = couplingsPtr->af(idAbs); |
---|
736 | |
---|
737 | // Part via gamma^*/Z^0 propagator. No Z^0 coupling to H_R. |
---|
738 | double resProp = 1. / ( pow2(sH - m2Res) + pow2(sH * GamMRat) ); |
---|
739 | double sigma = 8. * pow2(alpEM) * ei*ei / sH2; |
---|
740 | if (leftRight == 1) sigma += 8. * pow2(alpEM) |
---|
741 | * (2. * ei * vi * preFac * (sH - m2Res) * resProp / sH |
---|
742 | + (vi * vi + ai * ai) * pow2(preFac) * resProp); |
---|
743 | |
---|
744 | // Part via t-channel lepton + interference; sum over possibilities. |
---|
745 | if (idAbs == 11 || idAbs == 13 || idAbs == 15) { |
---|
746 | double yuk2Sum; |
---|
747 | if (idAbs == 11) yuk2Sum |
---|
748 | = pow2(yukawa[1][1]) + pow2(yukawa[2][1]) + pow2(yukawa[3][1]); |
---|
749 | else if (idAbs == 13) yuk2Sum |
---|
750 | = pow2(yukawa[2][1]) + pow2(yukawa[2][2]) + pow2(yukawa[3][2]); |
---|
751 | else yuk2Sum |
---|
752 | = pow2(yukawa[3][1]) + pow2(yukawa[3][2]) + pow2(yukawa[3][3]); |
---|
753 | yuk2Sum /= 4. * M_PI; |
---|
754 | sigma += 8. * alpEM * ei * yuk2Sum / (sH * tH) |
---|
755 | + 4. * pow2(yuk2Sum) / tH2; |
---|
756 | if (leftRight == 1) sigma += 8. * alpEM * (vi + ai) * yuk2Sum |
---|
757 | * preFac * (sH - m2Res) * resProp / tH; |
---|
758 | } |
---|
759 | |
---|
760 | // Common kinematical factor. Colour factor. |
---|
761 | sigma *= M_PI * (tH * uH - s3 * s4) / sH2; |
---|
762 | if (idAbs < 9) sigma /= 3.; |
---|
763 | |
---|
764 | // Answer. |
---|
765 | return sigma; |
---|
766 | |
---|
767 | } |
---|
768 | |
---|
769 | //-------------------------------------------------------------------------- |
---|
770 | |
---|
771 | // Select identity, colour and anticolour. |
---|
772 | |
---|
773 | void Sigma2ffbar2HchgchgHchgchg::setIdColAcol() { |
---|
774 | |
---|
775 | // Outgoing flavours trivial. |
---|
776 | setId( id1, id2, idHLR, -idHLR); |
---|
777 | |
---|
778 | // tHat is defined between incoming fermion and outgoing H--. |
---|
779 | if (id1 > 0) swapTU = true; |
---|
780 | |
---|
781 | // No colours at all or one flow topology. Swap if first is antiquark. |
---|
782 | if (abs(id1) < 9) setColAcol( 1, 0, 0, 1, 0, 0, 0, 0); |
---|
783 | else setColAcol( 0, 0, 0, 0, 0, 0, 0, 0); |
---|
784 | if (id1 < 0) swapColAcol(); |
---|
785 | |
---|
786 | } |
---|
787 | |
---|
788 | //-------------------------------------------------------------------------- |
---|
789 | |
---|
790 | // Evaluate weight for H_L/R sequential decay angles. |
---|
791 | |
---|
792 | double Sigma2ffbar2HchgchgHchgchg::weightDecay( Event& process, |
---|
793 | int iResBeg, int iResEnd) { |
---|
794 | |
---|
795 | // Identity of mother of decaying reseonance(s). |
---|
796 | int idMother = process[process[iResBeg].mother1()].idAbs(); |
---|
797 | |
---|
798 | // For top decay hand over to standard routine. |
---|
799 | if (idMother == 6) |
---|
800 | return weightTopDecay( process, iResBeg, iResEnd); |
---|
801 | |
---|
802 | // Else isotropic decay. |
---|
803 | return 1.; |
---|
804 | |
---|
805 | } |
---|
806 | |
---|
807 | //========================================================================== |
---|
808 | |
---|
809 | } // end namespace Pythia8 |
---|