ThePEG/MatrixElement/MEee2gZ2qq.h

0001 // -*- C++ -*-
0002 //
0003 // MEee2gZ2qq.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_MEee2gZ2qq_H
0010 #define ThePEG_MEee2gZ2qq_H
0011 // This is the declaration of the MEee2gZ2qq class.
0012
0013 #include "ThePEG/MatrixElement/ME2to2QCD.h"
0014
0015 namespace ThePEG {
0016
0017 /**
0018  * The MEee2gZ2qq class implements the
0019  * \f$e^+e^-\rightarrow\gamma/Z^0\rightarrow q\bar{q}\f$ matrix
0020  * element. Both the continuum and \f$Z^0\f$ pole term as well as the
0021  * interference term is included. Although not a strict QCD matrix
0022  * element the class inherits from ME2to2QCD, mainly to inherit the
0023  * parameter for the number of active quark flavours.
0024  *
0025  * @see \ref MEee2gZ2qqInterfaces "The interfaces"
0026  * defined for MEee2gZ2qq.
0027  * @see ME2to2QCD
0028  */
0029 class MEee2gZ2qq: public ME2to2QCD {
0030
0031 public:
0032
0033   /** @name Standard constructors and destructors. */
0034   //@{
0035   /**
0036    * Default constructor.
0037    */
0038   MEee2gZ2qq();
0039   //@}
0040
0041 public:
0042
0043   /** @name Virtual functions required by the MEBase class. */
0044   //@{
0045   /**
0046    * Return the order in \f$\alpha_S\f$ in which this matrix element
0047    * is given. Returns .
0048    */
0049   virtual unsigned int orderInAlphaS() const;
0050
0051   /**
0052    * Return the order in \f$\alpha_{EM}\f$ in which this matrix
0053    * element is given. Returns 2.
0054    */
0055   virtual unsigned int orderInAlphaEW() const;
0056
0057   /**
0058    * The matrix element for the kinematical configuration
0059    * previously provided by the last call to setKinematics(), suitably
0060    * scaled by sHat() to give a dimension-less number.
0061    * @return the matrix element scaled with sHat() to give a
0062    * dimensionless number.
0063    */
0064   virtual double me2() const;
0065
0066   /**
0067    * Add all possible diagrams with the add() function.
0068    */
0069   virtual void getDiagrams() const;
0070
0071   /**
0072    * Return a Selector with possible colour geometries for the selected
0073    * diagram weighted by their relative probabilities.
0074    * @param diag the diagram chosen.
0075    * @return the possible colour geometries weighted by their
0076    * relative probabilities.
0077    */
0078   virtual Selector<const ColourLines *>
0079   colourGeometries(tcDiagPtr diag) const;
0080
0081   /**
0082    * Get diagram selector. With the information previously supplied with the
0083    * setKinematics method, a derived class may optionally
0084    * override this method to weight the given diagrams with their
0085    * (although certainly not physical) relative probabilities.
0086    * @param dv the diagrams to be weighted.
0087    * @return a Selector relating the given diagrams to their weights.
0088    */
0089   virtual Selector<DiagramIndex> diagrams(const DiagramVector & dv) const;
0090
0091   /**
0092    * Return the scale associated with the last set phase space point.
0093    */
0094   virtual Energy2 scale() const;
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    * Standard Init function used to initialize the interface.
0117    */
0118   static void Init();
0119
0120 protected:
0121
0122   /** @name Clone Methods. */
0123   //@{
0124   /**
0125    * Make a simple clone of this object.
0126    * @return a pointer to the new object.
0127    */
0128   virtual IBPtr clone() const;
0129
0130   /** Make a clone of this object, possibly modifying the cloned object
0131    * to make it sane.
0132    * @return a pointer to the new object.
0133    */
0134   virtual IBPtr fullclone() const;
0135   //@}
0136
0137   /** @name Standard Interfaced functions. */
0138   //@{
0139   /**
0140    * Initialize this object after the setup phase before saving an
0141    * EventGenerator to disk.
0142    * @throws InitException if object could not be initialized properly.
0143    */
0144   virtual void doinit();
0145   //@}
0146
0147 protected:
0148
0149   /**
0150    * Constants for the different terms set from the StandardModel in
0151    * the init() function.
0152    */
0153   vector<double> coefs;
0154
0155   /**
0156    * The squared mass of the Z0.
0157    */
0158   Energy2 mZ2;
0159
0160   /**
0161    * The squared width of the Z0.
0162    */
0163   Energy2 GZ2;
0164
0165   /**
0166    * The last continuum term to be used to select primary diagram.
0167    */
0168   mutable double lastCont;
0169
0170   /**
0171    * The last Breit-Wigner term to be used to select primary diagram.
0172    */
0173   mutable double lastBW;
0174
0175 private:
0176
0177   /**
0178    * Describe a concrete class with persistent data.
0179    */
0180   static ClassDescription<MEee2gZ2qq> initMEee2gZ2qq;
0181
0182   /**
0183    *  Private and non-existent assignment operator.
0184    */
0185   MEee2gZ2qq & operator=(const MEee2gZ2qq &) = delete;
0186
0187 };
0188
0189 /** @cond TRAITSPECIALIZATIONS */
0190
0191 /** This template specialization informs ThePEG about the
0192  *  base classes of MEee2gZ2qq. */
0193 template <>
0194 struct BaseClassTrait<MEee2gZ2qq,1>: public ClassTraitsType {
0195   /** Typedef of the first base class of MEee2gZ2qq. */
0196   typedef ME2to2QCD NthBase;
0197 };
0198
0199 /** This template specialization informs ThePEG about the name of the
0200  *  MEee2gZ2qq class and the shared object where it is defined. */
0201 template <>
0202 struct ClassTraits<MEee2gZ2qq>: public ClassTraitsBase<MEee2gZ2qq> {
0203   /** Return a platform-independent class name */
0204   static string className() { return "ThePEG::MEee2gZ2qq"; }
0205   /** Return the name of the shared library be loaded to get
0206    *  access to the MEee2gZ2qq class and every other class it uses
0207    *  (except the base class). */
0208   static string library() { return "MEee2gZ2qq.so"; }
0209 };
0210
0211 /** @endcond */
0212
0213 }
0214
0215 #endif /* ThePEG_MEee2gZ2qq_H */