Matchbox/Dipoles/FFggxDipole.h

0001 // -*- C++ -*-
0002 //
0003 // FFggxDipole.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_FFggxDipole_H
0010 #define HERWIG_FFggxDipole_H
0011 //
0012 // This is the declaration of the FFggxDipole class.
0013 //
0014
0015 #include "Herwig/MatrixElement/Matchbox/Dipoles/SubtractionDipole.h"
0016
0017 namespace Herwig {
0018
0019 using namespace ThePEG;
0020
0021 /**
0022  * \ingroup Matchbox
0023  * \author Simon Platzer
0024  *
0025  * \brief FFggxDipole implements the D_{g,g;k} subtraction dipole.
0026  *
0027  */
0028 class FFggxDipole: public SubtractionDipole {
0029
0030 public:
0031
0032   /**
0033    * The default constructor.
0034    */
0035   FFggxDipole();
0036
0037 public:
0038
0039   /**
0040    * Return true, if this dipole can possibly handle the indicated
0041    * emitter.
0042    */
0043   virtual bool canHandleEmitter(const cPDVector& partons, int emitter) const {
0044     return emitter > 1 && partons[emitter]->id() == ParticleID::g;
0045   }
0046
0047   /**
0048    * Return true, if this dipole can possibly handle the indicated
0049    * splitting.
0050    */
0051   virtual bool canHandleSplitting(const cPDVector& partons, int emitter, int emission) const {
0052     return canHandleEmitter(partons,emitter) && partons[emission]->id() == ParticleID::g;
0053   }
0054
0055   /**
0056    * Return true, if this dipole can possibly handle the indicated
0057    * spectator.
0058    */
0059   virtual bool canHandleSpectator(const cPDVector& partons, int spectator) const {
0060     return spectator > 1 && partons[spectator]->coloured();
0061   }
0062
0063   /**
0064    * Return true, if this dipole applies to the selected
0065    * configuration.
0066    */
0067   virtual bool canHandle(const cPDVector& partons,
0068              int emitter, int emission, int spectator) const;
0069
0070   /**
0071    * Return true, if this dipole is symmetric with respect to emitter
0072    * and emission.
0073    */
0074   virtual bool isSymmetric() const { return true; }
0075
0076   /**
0077    *  How to sample the z-distribution.
0078    *  FlatZ = 1
0079    *  OneOverZ = 2
0080    *  OneOverOneMinusZ = 3
0081    *  OneOverZOneMinusZ = 4
0082    */
0083
0084   virtual int samplingZ() const {return 4;}
0085
0086
0087   /**
0088    * Return the matrix element for the kinematical configuation
0089    * previously provided by the last call to setKinematics(), suitably
0090    * scaled by sHat() to give a dimension-less number.
0091    */
0092   virtual double me2() const;
0093
0094   /**
0095    * Return the matrix element averaged over spin correlations.
0096    */
0097   virtual double me2Avg(double ccme2) const;
0098
0099 public:
0100
0101   /** @name Functions used by the persistent I/O system. */
0102   //@{
0103   /**
0104    * Function used to write out object persistently.
0105    * @param os the persistent output stream written to.
0106    */
0107   void persistentOutput(PersistentOStream & os) const;
0108
0109   /**
0110    * Function used to read in object persistently.
0111    * @param is the persistent input stream read from.
0112    * @param version the version number of the object when written.
0113    */
0114   void persistentInput(PersistentIStream & is, int version);
0115   //@}
0116
0117   /**
0118    * The standard Init function used to initialize the interfaces.
0119    * Called exactly once for each class by the class description system
0120    * before the main function starts or
0121    * when this class is dynamically loaded.
0122    */
0123   static void Init();
0124
0125 protected:
0126
0127   /** @name Clone Methods. */
0128   //@{
0129   /**
0130    * Make a simple clone of this object.
0131    * @return a pointer to the new object.
0132    */
0133   virtual IBPtr clone() const;
0134
0135   /** Make a clone of this object, possibly modifying the cloned object
0136    * to make it sane.
0137    * @return a pointer to the new object.
0138    */
0139   virtual IBPtr fullclone() const;
0140   //@}
0141
0142
0143 // If needed, insert declarations of virtual function defined in the
0144 // InterfacedBase class here (using ThePEG-interfaced-decl in Emacs).
0145
0146
0147 private:
0148
0149   /**
0150    * The assignment operator is private and must never be called.
0151    * In fact, it should not even be implemented.
0152    */
0153   FFggxDipole & operator=(const FFggxDipole &) = delete;
0154
0155 };
0156
0157 }
0158
0159 #endif /* HERWIG_FFggxDipole_H */