ThePEG/MatrixElement/MEGG2QQ.h

0001 // -*- C++ -*-
0002 //
0003 // MEGG2QQ.h is a part of ThePEG - Toolkit for HEP Event Generation
0004 // Copyright (C) 1999-2019 Leif Lonnblad
0005 //
0006 // ThePEG 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 ThePEG_MEGG2QQ_H
0010 #define ThePEG_MEGG2QQ_H
0011 // This is the declaration of the MEGG2QQ class.
0012
0013 #include "ThePEG/MatrixElement/ME2to2QCD.h"
0014
0015 namespace ThePEG {
0016
0017 /**
0018  * MEGG2QQ inherits from ME2to2QCD and implements the standard
0019  * \f$gg\rightarrow gq\bar{q}\f$ matrix element.
0020  *
0021  * @see \ref MEGG2QQInterfaces "The interfaces"
0022  * defined for MEGG2QQ.
0023  * @see ME2to2QCD
0024  */
0025 class MEGG2QQ: public ME2to2QCD {
0026
0027 public:
0028
0029   /** @name Virtual functions required by the MEBase class. */
0030   //@{
0031   /**
0032    * The matrix element for the kinematical configuration
0033    * previously provided by the last call to setKinematics(), suitably
0034    * scaled by sHat() to give a dimension-less number.
0035    * @return the matrix element scaled with sHat() to give a
0036    * dimensionless number.
0037    */
0038   virtual double me2() const;
0039
0040   /**
0041    * Add all possible diagrams with the add() function.
0042    */
0043   virtual void getDiagrams() const;
0044
0045   /**
0046    * Return a Selector with possible colour geometries for the selected
0047    * diagram weighted by their relative probabilities.
0048    * @param diag the diagram chosen.
0049    * @return the possible colour geometries weighted by their
0050    * relative probabilities.
0051    */
0052   virtual Selector<const ColourLines *>
0053   colourGeometries(tcDiagPtr diag) const;
0054
0055   /**
0056    * Get diagram selector. With the information previously supplied with the
0057    * setKinematics method, a derived class may optionally
0058    * override this method to weight the given diagrams with their
0059    * (although certainly not physical) relative probabilities.
0060    * @param dv the diagrams to be weighted.
0061    * @return a Selector relating the given diagrams to their weights.
0062    */
0063   virtual Selector<DiagramIndex> diagrams(const DiagramVector & dv) const;
0064   //@}
0065
0066 protected:
0067
0068   /** @name Internal functions returning the matrix element squared
0069    *  for different colour configurations. */
0070   //@{
0071   /**
0072    * Return the matrix element squared (without common pre-factors)
0073    * for the specific colour configuration.
0074    */
0075   double colA() const
0076   {
0077     return uHat()/tHat() - 2.0*sqr(uHat()/sHat());
0078   }
0079
0080   /**
0081    * Return the matrix element squared (without common pre-factors)
0082    * for the specific colour configuration.
0083    */
0084   double colB() const
0085   {
0086     return tHat()/uHat() - 2.0*sqr(tHat()/sHat());
0087   }
0088   //@}
0089
0090 public:
0091
0092   /**
0093    * Standard Init function used to initialize the interfaces.
0094    */
0095   static void Init();
0096
0097 protected:
0098
0099   /** @name Clone Methods. */
0100   //@{
0101   /**
0102    * Make a simple clone of this object.
0103    * @return a pointer to the new object.
0104    */
0105   virtual IBPtr clone() const;
0106
0107   /** Make a clone of this object, possibly modifying the cloned object
0108    * to make it sane.
0109    * @return a pointer to the new object.
0110    */
0111   virtual IBPtr fullclone() const;
0112   //@}
0113
0114 private:
0115
0116   /**
0117    * Describe a concrete class without persistent data.
0118    */
0119   static NoPIOClassDescription<MEGG2QQ> initMEGG2QQ;
0120
0121   /**
0122    *  Private and non-existent assignment operator.
0123    */
0124   MEGG2QQ & operator=(const MEGG2QQ &) = delete;
0125
0126 };
0127
0128 }
0129
0130
0131 namespace ThePEG {
0132
0133 /** @cond TRAITSPECIALIZATIONS */
0134
0135 /** This template specialization informs ThePEG about the
0136  *  base classes of MEGG2QQ. */
0137 template <>
0138 struct BaseClassTrait<MEGG2QQ,1>: public ClassTraitsType {
0139   /** Typedef of the first base class of MEGG2QQ. */
0140   typedef ME2to2QCD NthBase;
0141 };
0142
0143 /** This template specialization informs ThePEG about the name of
0144  *  the MEGG2QQ class and the shared object where it is defined. */
0145 template <>
0146 struct ClassTraits<MEGG2QQ>: public ClassTraitsBase<MEGG2QQ> {
0147   /** Return a platform-independent class name */
0148   static string className() { return "ThePEG::MEGG2QQ"; }
0149   /** Return the name of the shared library be loaded to get
0150    *  access to the MEGG2QQ class and every other class it uses
0151    *  (except the base class). */
0152   static string library() { return "MEQCD.so"; }
0153 };
0154
0155 /** @endcond */
0156
0157 }
0158
0159 #endif /* ThePEG_MEGG2QQ_H */