MatrixElement/General/MEff2ss.h

0001 // -*- C++ -*-
0002 //
0003 // MEff2ss.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_MEff2ss_H
0010 #define HERWIG_MEff2ss_H
0011 //
0012 // This is the declaration of the MEff2ss class.
0013 //
0014
0015 #include "GeneralHardME.h"
0016 #include "ThePEG/Helicity/Vertex/AbstractFFSVertex.h"
0017 #include "ThePEG/Helicity/Vertex/AbstractRFSVertex.h"
0018 #include "ThePEG/Helicity/Vertex/AbstractFFVVertex.h"
0019 #include "ThePEG/Helicity/Vertex/AbstractVSSVertex.h"
0020 #include "ThePEG/Helicity/Vertex/AbstractSSSVertex.h"
0021 #include "ThePEG/Helicity/Vertex/AbstractFFTVertex.h"
0022 #include "ThePEG/Helicity/Vertex/AbstractSSTVertex.h"
0023 #include "ThePEG/Helicity/Vertex/AbstractFFSSVertex.h"
0024 #include "Herwig/MatrixElement/ProductionMatrixElement.h"
0025
0026 namespace Herwig {
0027 using namespace ThePEG;
0028 using ThePEG::Helicity::SpinorWaveFunction;
0029 using ThePEG::Helicity::SpinorBarWaveFunction;
0030 using ThePEG::Helicity::ScalarWaveFunction;
0031
0032 /**
0033  * The MEff2ss class is designed to implement the matrix element for a
0034  * fermion-antifermion to scalar-scalar hard process. It inherits from
0035  * GeneralHardME and implements the appropriate virtual functions for this
0036  * specific spin combination.
0037  *
0038  * @see GeneralHardME
0039  */
0040 class MEff2ss: public GeneralHardME {
0041
0042 public:
0043
0044   /** Vector of SpinorWaveFunctions objects */
0045   typedef vector<SpinorWaveFunction> SpinorVector;
0046
0047   /** Vector of SpinorBarWaveFunction objects. */
0048   typedef vector<SpinorBarWaveFunction> SpinorBarVector;
0049
0050 public:
0051
0052   /** @name Virtual functions required by the MEBase class. */
0053   //@{
0054   /**
0055    * The matrix element for the kinematical configuration
0056    * previously provided by the last call to setKinematics(), suitably
0057    * scaled by sHat() to give a dimension-less number.
0058    * @return the matrix element scaled with sHat() to give a
0059    * dimensionless number.
0060    */
0061   virtual double me2() const;
0062   //@}
0063
0064   /**
0065    * Construct the vertex information for the spin correlations
0066    * @param sub Pointer to the relevent SubProcess
0067    */
0068   virtual void constructVertex(tSubProPtr sub);
0069
0070 protected:
0071
0072   /**
0073    * A debugging function to test the value of me2 against an
0074    * analytic function.
0075    * @param me2 The value of the \f$ |\bar{\mathcal{M}}|^2 \f$
0076    */
0077   virtual void debug(double me2) const;
0078
0079 public:
0080
0081   /** @name Functions used by the persistent I/O system. */
0082   //@{
0083   /**
0084    * Function used to write out object persistently.
0085    * @param os the persistent output stream written to.
0086    */
0087   void persistentOutput(PersistentOStream & os) const;
0088
0089   /**
0090    * Function used to read in object persistently.
0091    * @param is the persistent input stream read from.
0092    * @param version the version number of the object when written.
0093    */
0094   void persistentInput(PersistentIStream & is, int version);
0095   //@}
0096
0097   /**
0098    * The standard Init function used to initialize the interfaces.
0099    * Called exactly once for each class by the class description system
0100    * before the main function starts or
0101    * when this class is dynamically loaded.
0102    */
0103   static void Init();
0104
0105
0106 protected:
0107
0108   /** @name Standard Interfaced functions. */
0109   //@{
0110   /**
0111    * Initialize this object after the setup phase before saving an
0112    * EventGenerator to disk.
0113    * @throws InitException if object could not be initialized properly.
0114    */
0115   virtual void doinit();
0116   //@}
0117
0118 protected:
0119
0120   /** @name Clone Methods. */
0121   //@{
0122   /**
0123    * Make a simple clone of this object.
0124    * @return a pointer to the new object.
0125    */
0126   virtual IBPtr clone() const {return new_ptr(*this);}
0127
0128   /** Make a clone of this object, possibly modifying the cloned object
0129    * to make it sane.
0130    * @return a pointer to the new object.
0131    */
0132   virtual IBPtr fullclone() const {return new_ptr(*this);}
0133   //@}
0134
0135 private:
0136
0137   /**
0138    * The assignment operator is private and must never be called.
0139    * In fact, it should not even be implemented.
0140    */
0141   MEff2ss & operator=(const MEff2ss &) = delete;
0142
0143 private:
0144
0145   /**
0146    * Calculate the matrix element
0147    * @param sp A vector of SpinorWaveFunction objects
0148    * @param sbar A vector of SpinorBarWaveFunction objects
0149    * @param sca1 A ScalarWaveFunction for an outgoing scalar
0150    * @param sca2 A ScalarWaveFunction for the other outgoing scalar
0151    * @param me2 The spin averaged matrix element
0152    * @param first Whether or not first call to decide if colour decomposition etc
0153    * should be calculated
0154    */
0155   ProductionMatrixElement ff2ssME(const SpinorVector & sp,
0156                   const SpinorBarVector & sbar,
0157                   const ScalarWaveFunction & sca1,
0158                   const ScalarWaveFunction & sca2,
0159                   double & me2, bool first) const;
0160
0161 private:
0162
0163   /**
0164    * Storage for dynamically cast vertices for a diagram with intermediate
0165    * vector
0166    */
0167   vector<pair<AbstractFFSVertexPtr, AbstractSSSVertexPtr> > scalar_;
0168
0169   /**
0170    * Storage for dynamically cast vertices for a diagram with intermediate
0171    * fermion
0172    */
0173   vector<pair<AbstractFFSVertexPtr, AbstractFFSVertexPtr> > fermion_;
0174
0175   /**
0176    * Storage for dynamically cast vertices for a diagram with intermediate
0177    * vector
0178    */
0179   vector<pair<AbstractFFVVertexPtr, AbstractVSSVertexPtr> > vector_;
0180
0181   /**
0182    * Storage for dynamically cast vertices for a diagram with intermediate
0183    * fermion
0184    */
0185   vector<pair<AbstractRFSVertexPtr, AbstractRFSVertexPtr> > RSfermion_;
0186
0187   /**
0188    * Storage for dynamically cast vertices for a diagram with intermediate
0189    * tensor
0190    */
0191   vector<pair<AbstractFFTVertexPtr, AbstractSSTVertexPtr> > tensor_;
0192
0193   /**
0194    *  Storage for dynamically cast 4 point vertices
0195    */
0196   vector<AbstractFFSSVertexPtr> fourPoint_;
0197 };
0198
0199 }
0200
0201 #endif /* HERWIG_MEff2ss_H */