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// StandardModel.h is a part of the PYTHIA event generator.
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// Copyright (C) 2012 Torbjorn Sjostrand.
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// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
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// Please respect the MCnet Guidelines, see GUIDELINES for details.
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// This file gives access to some Standard Model parameters.
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// AlphaStrong: fix or first- or second-order running alpha_strong.
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#ifndef Pythia8_StandardModel_H
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#define Pythia8_StandardModel_H
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#include "ParticleData.h"
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#include "PythiaStdlib.h"
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//==========================================================================
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// The AlphaStrong class calculates the alpha_strong value at an arbitrary
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// scale, given the value at m_Z, to zeroth, first or second order.
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AlphaStrong() : isInit(false) {}
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AlphaStrong(double valueIn, int orderIn = 1) {
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init( valueIn, orderIn) ;}
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// Initialization for given value at M_Z and given order.
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void init(double valueIn = 0.12, int orderIn = 1);
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// alpha_S value and Lambda values.
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double alphaS(double scale2);
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double alphaS1Ord(double scale2);
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double alphaS2OrdCorr(double scale2);
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double Lambda3() const { return Lambda3Save; }
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double Lambda4() const { return Lambda4Save; }
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double Lambda5() const { return Lambda5Save; }
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// Initialization data member; protected to allow inheritance.
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// Constants: could only be changed in the code itself.
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static const int NITER;
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static const double MC, MB, MZ, SAFETYMARGIN1, SAFETYMARGIN2;
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double valueRef, valueNow, scale2Now, scale2Min, Lambda3Save,
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Lambda4Save, Lambda5Save, Lambda3Save2, Lambda4Save2,
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Lambda5Save2, mc, mb, mZ, mc2, mb2;
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//==========================================================================
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// The AlphaEM class calculates the alpha_electromagnetic value at an
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// arbitrary scale, given the value at 0 and m_Z, to zeroth or first order.
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// Initialization for a given order.
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void init(int orderIn, Settings* settingsPtr);
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double alphaEM(double scale2);
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// Constants: could only be changed in the code itself.
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static const double MZ, Q2STEP[5], BRUNDEF[5];
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double alpEM0, alpEMmZ, mZ2, bRun[5], alpEMstep[5];
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//==========================================================================
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// The CoupSM class stores and returns electroweak couplings,
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// including Cabibbo-Kobayashi-Maskawa mass mixing matrix elements.
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// Initialize, normally from Pythia::init().
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void init(Settings& settings, Rndm* rndmPtrIn);
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// alpha_S value and Lambda values.
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double alphaS(double scale2) {return alphaSlocal.alphaS(scale2);}
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double alphaS1Ord(double scale2) {return alphaSlocal.alphaS1Ord(scale2);}
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double alphaS2OrdCorr(double scale2) {
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return alphaSlocal.alphaS2OrdCorr(scale2);}
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double Lambda3() const {return alphaSlocal.Lambda3();}
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double Lambda4() const {return alphaSlocal.Lambda4();}
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double Lambda5() const {return alphaSlocal.Lambda5();}
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// Return alpha_EM value.
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double alphaEM(double scale2) {return alphaEMlocal.alphaEM(scale2);}
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// Return electroweak mixing angle and Fermi constant.
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double sin2thetaW() {return s2tW;}
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double cos2thetaW() {return c2tW;}
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double sin2thetaWbar() {return s2tWbar;}
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double GF() {return GFermi;}
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// Return electroweak couplings of quarks and leptons.
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double ef(int idAbs) {return efSave[idAbs];}
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double vf(int idAbs) {return vfSave[idAbs];}
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double af(int idAbs) {return afSave[idAbs];}
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double t3f(int idAbs) {return 0.5*afSave[idAbs];}
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double lf(int idAbs) {return lfSave[idAbs];}
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double rf(int idAbs) {return rfSave[idAbs];}
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// Return some squared couplings and other combinations.
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double ef2(int idAbs) {return ef2Save[idAbs];}
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double vf2(int idAbs) {return vf2Save[idAbs];}
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double af2(int idAbs) {return af2Save[idAbs];}
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double efvf(int idAbs) {return efvfSave[idAbs];}
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double vf2af2(int idAbs) {return vf2af2Save[idAbs];}
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// Return CKM value or square:
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// first index 1/2/3/4 = u/c/t/t', second 1/2/3/4 = d/s/b/b'.
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double VCKMgen(int genU, int genD) {return VCKMsave[genU][genD];}
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double V2CKMgen(int genU, int genD) {return V2CKMsave[genU][genD];}
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// Return CKM value or square for incoming flavours (sign irrelevant).
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double VCKMid(int id1, int id2);
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double V2CKMid(int id1, int id2);
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// Return CKM sum of squares for given inflavour, or random outflavour.
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double V2CKMsum(int id) {return V2CKMout[abs(id)];}
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int V2CKMpick(int id);
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// Constants: could only be changed in the code itself.
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static const double efSave[20], afSave[20];
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// Couplings and VCKM matrix (index 0 not used).
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double s2tW, c2tW, s2tWbar, GFermi, vfSave[20], lfSave[20], rfSave[20],
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ef2Save[20], vf2Save[20], af2Save[20], efvfSave[20],
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vf2af2Save[20], VCKMsave[5][5], V2CKMsave[5][5], V2CKMout[20];
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// Pointer to the random number generator.
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// An AlphaStrong instance for general use (but not MPI, ISR, FSR).
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AlphaStrong alphaSlocal;
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// An AlphaEM instance for general use (but not MPI, ISR, FSR).
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AlphaEM alphaEMlocal;
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//==========================================================================
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// Generic couplings class
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class Couplings : public CoupSM {
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Couplings() : isSUSY(false) {}
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//==========================================================================
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} // end namespace Pythia8
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#endif // Pythia8_StandardModel_H
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include/StandardModel.h
