[1] | 1 | // StandardModel.h is a part of the PYTHIA event generator. |
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| 2 | // Copyright (C) 2012 Torbjorn Sjostrand. |
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| 3 | // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details. |
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| 4 | // Please respect the MCnet Guidelines, see GUIDELINES for details. |
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| 5 | |
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| 6 | // This file gives access to some Standard Model parameters. |
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| 7 | // AlphaStrong: fix or first- or second-order running alpha_strong. |
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| 8 | |
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| 9 | #ifndef Pythia8_StandardModel_H |
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| 10 | #define Pythia8_StandardModel_H |
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| 11 | |
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| 12 | #include "ParticleData.h" |
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| 13 | #include "PythiaStdlib.h" |
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| 14 | |
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| 15 | namespace Pythia8 { |
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| 16 | |
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| 17 | //========================================================================== |
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| 18 | |
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| 19 | // The AlphaStrong class calculates the alpha_strong value at an arbitrary |
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| 20 | // scale, given the value at m_Z, to zeroth, first or second order. |
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| 21 | |
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| 22 | class AlphaStrong { |
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| 23 | |
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| 24 | public: |
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| 25 | |
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| 26 | // Constructors. |
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| 27 | AlphaStrong() : isInit(false), lastCallToFull(false), order(0), |
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| 28 | valueRef(0.), valueNow(0.), scale2Now(0.), Lambda3Save(0.), |
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| 29 | Lambda4Save(0.), Lambda5Save(0.), scale2Min(0.), Lambda3Save2(0.), |
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| 30 | Lambda4Save2(0.), Lambda5Save2(0.), mc2(0.), mb2(0.) {} |
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| 31 | AlphaStrong(double valueIn, int orderIn = 1) { |
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| 32 | init( valueIn, orderIn) ;} |
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| 33 | |
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| 34 | // Initialization for given value at M_Z and given order. |
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| 35 | void init(double valueIn = 0.12, int orderIn = 1); |
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| 36 | |
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| 37 | // alpha_S value and Lambda values. |
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| 38 | double alphaS(double scale2); |
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| 39 | double alphaS1Ord(double scale2); |
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| 40 | double alphaS2OrdCorr(double scale2); |
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| 41 | double Lambda3() const { return Lambda3Save; } |
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| 42 | double Lambda4() const { return Lambda4Save; } |
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| 43 | double Lambda5() const { return Lambda5Save; } |
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| 44 | |
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| 45 | protected: |
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| 46 | |
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| 47 | // Initialization data member; protected to allow inheritance. |
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| 48 | bool isInit; |
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| 49 | |
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| 50 | private: |
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| 51 | |
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| 52 | // Constants: could only be changed in the code itself. |
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| 53 | static const int NITER; |
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| 54 | static const double MC, MB, MZ, SAFETYMARGIN1, SAFETYMARGIN2; |
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| 55 | |
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| 56 | // Data members. |
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| 57 | bool lastCallToFull; |
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| 58 | int order; |
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| 59 | double valueRef, valueNow, scale2Now, Lambda3Save, Lambda4Save, |
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| 60 | Lambda5Save, scale2Min, Lambda3Save2, Lambda4Save2, |
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| 61 | Lambda5Save2, mc2, mb2; |
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| 62 | |
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| 63 | }; |
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| 64 | |
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| 65 | //========================================================================== |
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| 66 | |
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| 67 | // The AlphaEM class calculates the alpha_electromagnetic value at an |
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| 68 | // arbitrary scale, given the value at 0 and m_Z, to zeroth or first order. |
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| 69 | |
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| 70 | class AlphaEM { |
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| 71 | |
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| 72 | public: |
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| 73 | |
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| 74 | // Constructors. |
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| 75 | AlphaEM() {} |
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| 76 | |
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| 77 | // Initialization for a given order. |
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| 78 | void init(int orderIn, Settings* settingsPtr); |
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| 79 | |
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| 80 | // alpha_EM value. |
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| 81 | double alphaEM(double scale2); |
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| 82 | |
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| 83 | private: |
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| 84 | |
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| 85 | // Constants: could only be changed in the code itself. |
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| 86 | static const double MZ, Q2STEP[5], BRUNDEF[5]; |
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| 87 | |
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| 88 | // Data members. |
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| 89 | int order; |
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| 90 | double alpEM0, alpEMmZ, mZ2, bRun[5], alpEMstep[5]; |
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| 91 | |
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| 92 | }; |
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| 93 | |
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| 94 | //========================================================================== |
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| 95 | |
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| 96 | // The CoupSM class stores and returns electroweak couplings, |
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| 97 | // including Cabibbo-Kobayashi-Maskawa mass mixing matrix elements. |
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| 98 | |
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| 99 | class CoupSM { |
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| 100 | |
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| 101 | public: |
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| 102 | |
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| 103 | // Constructor. |
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| 104 | CoupSM() {} |
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| 105 | |
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| 106 | // Initialize, normally from Pythia::init(). |
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| 107 | void init(Settings& settings, Rndm* rndmPtrIn); |
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| 108 | |
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| 109 | // alpha_S value and Lambda values. |
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| 110 | double alphaS(double scale2) {return alphaSlocal.alphaS(scale2);} |
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| 111 | double alphaS1Ord(double scale2) {return alphaSlocal.alphaS1Ord(scale2);} |
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| 112 | double alphaS2OrdCorr(double scale2) { |
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| 113 | return alphaSlocal.alphaS2OrdCorr(scale2);} |
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| 114 | double Lambda3() const {return alphaSlocal.Lambda3();} |
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| 115 | double Lambda4() const {return alphaSlocal.Lambda4();} |
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| 116 | double Lambda5() const {return alphaSlocal.Lambda5();} |
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| 117 | |
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| 118 | // Return alpha_EM value. |
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| 119 | double alphaEM(double scale2) {return alphaEMlocal.alphaEM(scale2);} |
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| 120 | |
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| 121 | // Return electroweak mixing angle and Fermi constant. |
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| 122 | double sin2thetaW() {return s2tW;} |
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| 123 | double cos2thetaW() {return c2tW;} |
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| 124 | double sin2thetaWbar() {return s2tWbar;} |
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| 125 | double GF() {return GFermi;} |
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| 126 | |
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| 127 | // Return electroweak couplings of quarks and leptons. |
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| 128 | double ef(int idAbs) {return efSave[idAbs];} |
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| 129 | double vf(int idAbs) {return vfSave[idAbs];} |
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| 130 | double af(int idAbs) {return afSave[idAbs];} |
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| 131 | double t3f(int idAbs) {return 0.5*afSave[idAbs];} |
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| 132 | double lf(int idAbs) {return lfSave[idAbs];} |
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| 133 | double rf(int idAbs) {return rfSave[idAbs];} |
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| 134 | |
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| 135 | // Return some squared couplings and other combinations. |
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| 136 | double ef2(int idAbs) {return ef2Save[idAbs];} |
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| 137 | double vf2(int idAbs) {return vf2Save[idAbs];} |
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| 138 | double af2(int idAbs) {return af2Save[idAbs];} |
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| 139 | double efvf(int idAbs) {return efvfSave[idAbs];} |
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| 140 | double vf2af2(int idAbs) {return vf2af2Save[idAbs];} |
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| 141 | |
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| 142 | // Return CKM value or square: |
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| 143 | // first index 1/2/3/4 = u/c/t/t', second 1/2/3/4 = d/s/b/b'. |
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| 144 | double VCKMgen(int genU, int genD) {return VCKMsave[genU][genD];} |
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| 145 | double V2CKMgen(int genU, int genD) {return V2CKMsave[genU][genD];} |
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| 146 | |
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| 147 | // Return CKM value or square for incoming flavours (sign irrelevant). |
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| 148 | double VCKMid(int id1, int id2); |
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| 149 | double V2CKMid(int id1, int id2); |
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| 150 | |
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| 151 | // Return CKM sum of squares for given inflavour, or random outflavour. |
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| 152 | double V2CKMsum(int id) {return V2CKMout[abs(id)];} |
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| 153 | int V2CKMpick(int id); |
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| 154 | |
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| 155 | protected: |
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| 156 | |
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| 157 | // Constants: could only be changed in the code itself. |
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| 158 | static const double efSave[20], afSave[20]; |
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| 159 | |
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| 160 | // Couplings and VCKM matrix (index 0 not used). |
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| 161 | double s2tW, c2tW, s2tWbar, GFermi, vfSave[20], lfSave[20], rfSave[20], |
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| 162 | ef2Save[20], vf2Save[20], af2Save[20], efvfSave[20], |
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| 163 | vf2af2Save[20], VCKMsave[5][5], V2CKMsave[5][5], V2CKMout[20]; |
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| 164 | |
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| 165 | // Pointer to the random number generator. |
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| 166 | Rndm* rndmPtr; |
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| 167 | |
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| 168 | // An AlphaStrong instance for general use (but not MPI, ISR, FSR). |
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| 169 | AlphaStrong alphaSlocal; |
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| 170 | |
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| 171 | // An AlphaEM instance for general use (but not MPI, ISR, FSR). |
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| 172 | AlphaEM alphaEMlocal; |
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| 173 | |
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| 174 | }; |
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| 175 | |
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| 176 | //========================================================================== |
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| 177 | |
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| 178 | // Generic couplings class |
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| 179 | |
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| 180 | class Couplings : public CoupSM { |
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| 181 | |
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| 182 | public: |
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| 183 | |
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| 184 | Couplings() : isSUSY(false) {} |
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| 185 | bool isSUSY; |
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| 186 | |
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| 187 | }; |
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| 188 | |
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| 189 | //========================================================================== |
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| 190 | |
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| 191 | } // end namespace Pythia8 |
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| 192 | |
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| 193 | #endif // Pythia8_StandardModel_H |
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