Builtin/Amplitudes/MG_gg2ttx.h

0001 // -*- C++ -*-
0002 //
0003 // MG_gg2ttx.h is a part of Herwig - A multi-purpose Monte Carlo event generator
0004 // Copyright (C) 2002-2019 The Herwig Collaboration
0005 //
0006 // Herwig is licenced under version 3 of the GPL, see COPYING for details.
0007 // Please respect the MCnet academic guidelines, see GUIDELINES for details.
0008 //
0009 #ifndef MG5_Sigma_sm_gg2ttx_H
0010 #define MG5_Sigma_sm_gg2ttx_H
0011 //
0012 // This is the declaration of the MG_gg2ttx class.
0013 //
0014
0015 #include <complex>
0016 #include <vector>
0017 #include "Parameters_sm.h"
0018
0019 using namespace std;
0020
0021 class MG_gg2ttx
0022 {
0023   public:
0024
0025     // Constructor.
0026     MG_gg2ttx() {}
0027
0028     // Initialize process using Herwig parameters
0029     virtual void initProc(map<string, double> & MGParams);
0030
0031     // Calculate flavour-independent parts of cross section.
0032     virtual void sigmaKin(vector<std::complex<double> >& amps, const vector<int>& hel);
0033
0034     // Set momenta for matrix element evaluation
0035     void setMomenta(vector < double * > & momenta){p = momenta;}
0036
0037     // number of external particles
0038     static const int nexternal = 4;
0039
0040     // number of colour ordered amplitudes
0041     static const int namplitudes = 3;
0042     std::complex<double> amp[namplitudes];
0043
0044   private:
0045     // Calculate wavefunctions
0046     void calculate_wavefunctions(const int perm[], const int hel[]);
0047
0048     // number of wavefunctions used in calculate_wavefunctions
0049     static const int nwavefuncs = 7;
0050     std::complex<double> w[nwavefuncs][18];
0051
0052     // Pointer to the model parameters
0053     Parameters_sm * pars;
0054
0055     // vector with external particle masses
0056     vector<double> mME;
0057
0058     // vector with momenta
0059     vector < double * > p;
0060
0061 };
0062
0063
0064 #endif  // MG5_Sigma_sm_gg2ttx_H