Builtin/Amplitudes/MatchboxAmplitudeggttbarg.h

0001 // -*- C++ -*-
0002 //
0003 // MatchboxAmplitudeggttbarg.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 Herwig_MatchboxAmplitudeggttbarg_H
0010 #define Herwig_MatchboxAmplitudeggttbarg_H
0011 //
0012 // This is the declaration of the MatchboxAmplitudeggttbarg class.
0013 //
0014
0015 #include "Herwig/MatrixElement/Matchbox/Base/MatchboxAmplitude.h"
0016 #include "Herwig/MatrixElement/Matchbox/Builtin/Amplitudes/MatchboxCurrents.h"
0017 #include "MG_gg2ttxg.h"
0018 #include "HelAmps_sm.h"
0019
0020 namespace Herwig {
0021
0022 using namespace ThePEG;
0023
0024 /**
0025  * \ingroup Matchbox
0026  * \author Alix Wilcock
0027  *
0028  * \brief MatchboxAmplitudeggttbarg
0029  */
0030 class MatchboxAmplitudeggttbarg:
0031     public MatchboxAmplitude, public MatchboxCurrents {
0032
0033 public:
0034
0035   /**
0036    * The default constructor.
0037    */
0038   MatchboxAmplitudeggttbarg();
0039
0040 public:
0041
0042   /**
0043    * Return true, if this amplitude can handle the given process.
0044    */
0045   virtual bool canHandle(const PDVector&) const;
0046
0047   /**
0048    * Return the (tree-level) order in \f$g_S\f$ in which this matrix
0049    * element is given.
0050    */
0051   virtual unsigned int orderInGs() const {return 3; }
0052
0053   /**
0054    * Return the (tree-level) order in \f$g_{EM}\f$ in which this matrix
0055    * element is given.
0056    */
0057   virtual unsigned int orderInGem() const { return 0; }
0058
0059   /**
0060    * Return true, if this amplitude will not require colour correlations.
0061    */
0062   virtual bool noCorrelations() const { return true; }
0063
0064   /**
0065    * Return true, if this amplitude is capable of calculating one-loop
0066    * (QCD) corrections.
0067    */
0068   virtual bool haveOneLoop() const { return false; }
0069
0070   /**
0071    * Calculate the tree level amplitudes for the phasespace point
0072    * stored in lastXComb.
0073    */
0074   virtual void prepareAmplitudes(Ptr<MatchboxMEBase>::tcptr);
0075
0076   /**
0077    * Evaluate the amplitude for the given colour tensor id and
0078    * helicity assignment
0079    */
0080   virtual Complex evaluate(size_t, const vector<int>&, Complex&);
0081
0082   /**
0083    * Return the value of the dimensional regularization
0084    * parameter. Note that renormalization scale dependence is fully
0085    * restored in DipoleIOperator.
0086    */
0087   virtual Energy2 mu2() const { return lastSHat(); }
0088
0089   /**
0090    * Flush all cashes.
0091    */
0092   virtual void flushCaches() {
0093     MatchboxCurrents::reset();
0094     MatchboxAmplitude::flushCaches();
0095   }
0096
0097 public:
0098
0099   /** @name Functions used by the persistent I/O system. */
0100   //@{
0101   /**
0102    * Function used to write out object persistently.
0103    * @param os the persistent output stream written to.
0104    */
0105   void persistentOutput(PersistentOStream & os) const;
0106
0107   /**
0108    * Function used to read in object persistently.
0109    * @param is the persistent input stream read from.
0110    * @param version the version number of the object when written.
0111    */
0112   void persistentInput(PersistentIStream & is, int version);
0113   //@}
0114
0115   /**
0116    * The standard Init function used to initialize the interfaces.
0117    * Called exactly once for each class by the class description system
0118    * before the main function starts or
0119    * when this class is dynamically loaded.
0120    */
0121   static void Init();
0122
0123 protected:
0124
0125   /** @name Clone Methods. */
0126   //@{
0127   /**
0128    * Make a simple clone of this object.
0129    * @return a pointer to the new object.
0130    */
0131   virtual IBPtr clone() const;
0132
0133   /** Make a clone of this object, possibly modifying the cloned object
0134    * to make it sane.
0135    * @return a pointer to the new object.
0136    */
0137   virtual IBPtr fullclone() const;
0138   //@}
0139
0140
0141 // If needed, insert declarations of virtual function defined in the
0142 // InterfacedBase class here (using ThePEG-interfaced-decl in Emacs).
0143
0144 protected:
0145
0146   /** @name Standard Interfaced functions. */
0147   //@{
0148   /**
0149    * Initialize this object after the setup phase before saving an
0150    * EventGenerator to disk.
0151    * @throws InitException if object could not be initialized properly.
0152    */
0153   virtual void doinit();
0154
0155   /**
0156    * Initialize this object. Called in the run phase just before
0157    * a run begins.
0158    */
0159   virtual void doinitrun();
0160
0161   //@}
0162
0163 private:
0164
0165   /**
0166    * The assignment operator is private and must never be called.
0167    * In fact, it should not even be implemented.
0168    */
0169   MatchboxAmplitudeggttbarg & operator=(const MatchboxAmplitudeggttbarg &) = delete;
0170
0171   /**
0172    * Containers for external particle momenta
0173    */
0174   double mom0 [4];
0175   double mom1 [4];
0176   double mom2 [4];
0177   double mom3 [4];
0178   double mom4 [4];
0179
0180   /**
0181    * Fill MGParams_ with Herwig values of parameters
0182    */
0183   void setupParams(map<string, double> & MGParams);
0184
0185   /**
0186    * Stores parameters needed in MG_process
0187    */
0188   map<string,double>  MGParams_;
0189
0190 };
0191
0192 }
0193
0194 #endif /* Herwig_MatchboxAmplitudeggttbarg_H */