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Herwig  7.2.1
MG_gg2ttx.h
1 // -*- C++ -*-
2 //
3 // MG_gg2ttx.h is a part of Herwig - A multi-purpose Monte Carlo event generator
4 // Copyright (C) 2002-2019 The Herwig Collaboration
5 //
6 // Herwig is licenced under version 3 of the GPL, see COPYING for details.
7 // Please respect the MCnet academic guidelines, see GUIDELINES for details.
8 //
9 #ifndef MG5_Sigma_sm_gg2ttx_H
10 #define MG5_Sigma_sm_gg2ttx_H
11 //
12 // This is the declaration of the MG_gg2ttx class.
13 //
14 
15 #include <complex>
16 #include <vector>
17 #include "Parameters_sm.h"
18 
19 using namespace std;
20 
21 class MG_gg2ttx
22 {
23  public:
24 
25  // Constructor.
26  MG_gg2ttx() {}
27 
28  // Initialize process using Herwig parameters
29  virtual void initProc(map<string, double> & MGParams);
30 
31  // Calculate flavour-independent parts of cross section.
32  virtual void sigmaKin(vector<std::complex<double> >& amps, const vector<int>& hel);
33 
34  // Set momenta for matrix element evaluation
35  void setMomenta(vector < double * > & momenta){p = momenta;}
36 
37  // number of external particles
38  static const int nexternal = 4;
39 
40  // number of colour ordered amplitudes
41  static const int namplitudes = 3;
42  std::complex<double> amp[namplitudes];
43 
44  private:
45  // Calculate wavefunctions
46  void calculate_wavefunctions(const int perm[], const int hel[]);
47 
48  // number of wavefunctions used in calculate_wavefunctions
49  static const int nwavefuncs = 7;
50  std::complex<double> w[nwavefuncs][18];
51 
52  // Pointer to the model parameters
53  Parameters_sm * pars;
54 
55  // vector with external particle masses
56  vector<double> mME;
57 
58  // vector with momenta
59  vector < double * > p;
60 
61 };
62 
63 
64 #endif // MG5_Sigma_sm_gg2ttx_H
STL namespace.