MatrixElement/General/MEvv2ff.h

0001 // -*- C++ -*-
0002 //
0003 // MEvv2ff.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_MEvv2ff_H
0010 #define HERWIG_MEvv2ff_H
0011 //
0012 // This is the declaration of the MEvv2ff class.
0013 //
0014
0015 #include "GeneralHardME.h"
0016 #include "ThePEG/Helicity/Vertex/AbstractFFSVertex.h"
0017 #include "ThePEG/Helicity/Vertex/AbstractVVSVertex.h"
0018 #include "ThePEG/Helicity/Vertex/AbstractFFVVertex.h"
0019 #include "ThePEG/Helicity/Vertex/AbstractRFVVertex.h"
0020 #include "ThePEG/Helicity/Vertex/AbstractVVVVertex.h"
0021 #include "ThePEG/Helicity/Vertex/AbstractVVTVertex.h"
0022 #include "ThePEG/Helicity/Vertex/AbstractFFTVertex.h"
0023 #include "ThePEG/Helicity/Vertex/AbstractFFVVVertex.h"
0024 #include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
0025 #include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
0026 #include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
0027 #include "Herwig/MatrixElement/ProductionMatrixElement.h"
0028
0029 namespace Herwig {
0030 using namespace ThePEG;
0031 using ThePEG::Helicity::SpinorWaveFunction;
0032 using ThePEG::Helicity::SpinorBarWaveFunction;
0033 using ThePEG::Helicity::VectorWaveFunction;
0034
0035 /**
0036  * This class is designed to implement the matrix element for the
0037  * \f$2 \rightarrow 2\f$ process vector-vector to fermion-antifermion pair. It
0038  * inherits from GeneralHardME and implements the me2() virtual function.
0039  *
0040  * @see GeneralHardME
0041  *
0042  */
0043 class MEvv2ff: public GeneralHardME {
0044
0045 public:
0046
0047   /** A Vector of VectorWaveFunction objects. */
0048   typedef vector<VectorWaveFunction> VBVector;
0049
0050   /** A vector of SpinorBarWaveFunction objects. */
0051   typedef vector<SpinorWaveFunction> SpinorVector;
0052
0053   /** A vector of SpinorBarWaveFunction objects. */
0054   typedef vector<SpinorBarWaveFunction> SpinorBarVector;
0055
0056 public:
0057
0058   /** @name Virtual functions required by the MEBase class. */
0059   //@{
0060   /**
0061    * The matrix element for the kinematical configuration
0062    * previously provided by the last call to setKinematics(), suitably
0063    * scaled by sHat() to give a dimension-less number.
0064    * @return the matrix element scaled with sHat() to give a
0065    * dimensionless number.
0066    */
0067   virtual double me2() const;
0068   //@}
0069
0070   /**
0071    * Construct the vertex information for the spin correlations
0072    * @param sub Pointer to the relevent SubProcess
0073    */
0074   virtual void constructVertex(tSubProPtr sub);
0075
0076 private:
0077
0078   /**
0079    * Calculate the value of the matrix element
0080    */
0081   ProductionMatrixElement vv2ffME(const VBVector & v1, const VBVector & v2,
0082                   const SpinorBarVector & sbar,
0083                   const SpinorVector & sp,
0084                   double & me2, bool first) const;
0085
0086 protected:
0087
0088   /**
0089    * A debugging function to test the value of me2 against an
0090    * analytic function.
0091    * @param me2 The value of the \f$ |\bar{\mathcal{M}}|^2 \f$
0092    */
0093   virtual void debug(double me2) const;
0094
0095 public:
0096
0097   /** @name Functions used by the persistent I/O system. */
0098   //@{
0099   /**
0100    * Function used to write out object persistently.
0101    * @param os the persistent output stream written to.
0102    */
0103   void persistentOutput(PersistentOStream & os) const;
0104
0105   /**
0106    * Function used to read in object persistently.
0107    * @param is the persistent input stream read from.
0108    * @param version the version number of the object when written.
0109    */
0110   void persistentInput(PersistentIStream & is, int version);
0111   //@}
0112
0113   /**
0114    * The standard Init function used to initialize the interfaces.
0115    * Called exactly once for each class by the class description system
0116    * before the main function starts or
0117    * when this class is dynamically loaded.
0118    */
0119   static void Init();
0120
0121
0122 protected:
0123
0124   /** @name Standard Interfaced functions. */
0125   //@{
0126   /**
0127    * Initialize this object after the setup phase before saving an
0128    * EventGenerator to disk.
0129    * @throws InitException if object could not be initialized properly.
0130    */
0131   virtual void doinit();
0132   //@}
0133
0134
0135 protected:
0136
0137   /** @name Clone Methods. */
0138   //@{
0139   /**
0140    * Make a simple clone of this object.
0141    * @return a pointer to the new object.
0142    */
0143   virtual IBPtr clone() const {return new_ptr(*this);}
0144
0145   /** Make a clone of this object, possibly modifying the cloned object
0146    * to make it sane.
0147    * @return a pointer to the new object.
0148    */
0149   virtual IBPtr fullclone() const {return new_ptr(*this);}
0150   //@}
0151
0152 private:
0153
0154   /**
0155    * The assignment operator is private and must never be called.
0156    * In fact, it should not even be implemented.
0157    */
0158   MEvv2ff & operator=(const MEvv2ff &) = delete;
0159
0160 private:
0161
0162   /** @name Dynamically casted vertices. */
0163   //@{
0164   /**
0165    *  Intermediate scalar
0166    */
0167   vector<pair<AbstractVVSVertexPtr, AbstractFFSVertexPtr > > scalar_;
0168
0169   /**
0170    * Intermediate fermion
0171    */
0172   vector<pair<AbstractFFVVertexPtr, AbstractFFVVertexPtr> > fermion_;
0173
0174   /**
0175    * Intermediate vector
0176    */
0177   vector<pair<AbstractVVVVertexPtr, AbstractFFVVertexPtr> > vector_;
0178
0179   /**
0180    * Intermediate RS fermion
0181    */
0182   vector<pair<AbstractRFVVertexPtr, AbstractRFVVertexPtr> > RSfermion_;
0183
0184   /**
0185    * Intermediate tensor
0186    */
0187   vector<pair<AbstractVVTVertexPtr, AbstractFFTVertexPtr> > tensor_;
0188
0189   /**
0190    *  Four point vertices
0191    */
0192   vector<AbstractFFVVVertexPtr> four_;
0193   //@}
0194 };
0195
0196 }
0197
0198 #endif /* HERWIG_MEvv2ff_H */