QTilde/SplittingFunctions/OneOneOneQEDSplitFn.h

0001 // -*- C++ -*-
0002 #ifndef Herwig_OneOneOneQEDSplitFn_H
0003 #define Herwig_OneOneOneQEDSplitFn_H
0004 //
0005 // This is the declaration of the OneOneOneQEDSplitFn class.
0006 //
0007
0008 #include "SplittingFunction.h"
0009 #include "Herwig/Models/StandardModel/StandardModel.h"
0010
0011 namespace Herwig {
0012
0013 using namespace ThePEG;
0014
0015 /**
0016  * The OneOneOneQEDSplitFn class implements the splitting function for
0017  * \f$\1\to q\1 1\f$ where the spin-1 particles are massive electroweak gauge bosons.
0018  *
0019  * @see \ref OneOneOneQEDSplitFnInterfaces "The interfaces"
0020  * defined for OneOneOneQEDSplitFn.
0021  */
0022 class OneOneOneQEDSplitFn: public SplittingFunction {
0023
0024 public:
0025
0026   /**
0027    *  Concrete implementation of the method to determine whether this splitting
0028    *  function can be used for a given set of particles.
0029    *  @param ids The PDG codes for the particles in the splitting.
0030    */
0031   virtual bool accept(const IdList & ids) const;
0032
0033   /**
0034    *   Methods to return the splitting function.
0035    */
0036   //@{
0037   /**
0038    * The concrete implementation of the splitting function, \f$P(z,t)\f$.
0039    * @param z   The energy fraction.
0040    * @param t   The scale.
0041    * @param ids The PDG codes for the particles in the splitting.
0042    * @param mass Whether or not to include the mass dependent terms
0043    * @param rho The spin density matrix
0044    */
0045   virtual double P(const double z, const Energy2 t, const IdList & ids,
0046            const bool mass, const RhoDMatrix & rho) const;
0047
0048   /**
0049    * The concrete implementation of the overestimate of the splitting function,
0050    * \f$P_{\rm over}\f$.
0051    * @param z   The energy fraction.
0052    * @param ids The PDG codes for the particles in the splitting.
0053    */
0054   virtual double overestimateP(const double z, const IdList & ids) const;
0055
0056   /**
0057    * The concrete implementation of the
0058    * the ratio of the splitting function to the overestimate, i.e.
0059    * \f$P(z,t)/P_{\rm over}(z)\f$.
0060    * @param z   The energy fraction.
0061    * @param t   The scale.
0062    * @param ids The PDG codes for the particles in the splitting.
0063    * @param mass Whether or not to include the mass dependent terms
0064    * @param rho The spin density matrix
0065    */
0066   virtual double ratioP(const double z, const Energy2 t, const IdList & ids,
0067             const bool mass, const RhoDMatrix & rho) const;
0068
0069   /**
0070    * The concrete implementation of the indefinite integral of the
0071    * overestimated splitting function, \f$P_{\rm over}\f$.
0072    * @param z   The energy fraction.
0073    * @param ids The PDG codes for the particles in the splitting.
0074    * @param PDFfactor Which additional factor to include for the PDF
0075    *                  0 is no additional factor,
0076    *                  1 is \f$1/z\f$, 2 is \f$1/(1-z)\f$ and 3 is \f$1/z/(1-z)\f$
0077    */
0078   virtual double integOverP(const double z, const IdList & ids,
0079                 unsigned int PDFfactor=0) const;
0080
0081   /**
0082    * The concrete implementation of the inverse of the indefinite integral.
0083    * @param r Value of the splitting function to be inverted
0084    * @param ids The PDG codes for the particles in the splitting.
0085    * @param PDFfactor Which additional factor to include for the PDF
0086    *                  0 is no additional factor,
0087    *                  1 is \f$1/z\f$, 2 is \f$1/(1-z)\f$ and 3 is \f$1/z/(1-z)\f$
0088    */
0089   virtual double invIntegOverP(const double r, const IdList & ids,
0090                    unsigned int PDFfactor=0) const;
0091   //@}
0092
0093   /**
0094    * Method to calculate the azimuthal angle
0095    * @param z The energy fraction
0096    * @param t The scale \f$t=2p_j\cdot p_k\f$.
0097    * @param ids The PDG codes for the particles in the splitting.
0098    * @param The azimuthal angle, \f$\phi\f$.
0099    * @return The weight
0100    */
0101   virtual vector<pair<int,Complex> >
0102   generatePhiForward(const double z, const Energy2 t, const IdList & ids,
0103           const RhoDMatrix &);
0104
0105   /**
0106    * Method to calculate the azimuthal angle for backward evolution
0107    * @param z The energy fraction
0108    * @param t The scale \f$t=2p_j\cdot p_k\f$.
0109    * @param ids The PDG codes for the particles in the splitting.
0110    * @param The azimuthal angle, \f$\phi\f$.
0111    * @return The weight
0112    */
0113   virtual vector<pair<int,Complex> >
0114   generatePhiBackward(const double z, const Energy2 t, const IdList & ids,
0115               const RhoDMatrix &);
0116
0117   /**
0118    * Calculate the matrix element for the splitting
0119    * @param z The energy fraction
0120    * @param t The scale \f$t=2p_j\cdot p_k\f$.
0121    * @param ids The PDG codes for the particles in the splitting.
0122    * @param The azimuthal angle, \f$\phi\f$.
0123    */
0124   virtual DecayMEPtr matrixElement(const double z, const Energy2 t,
0125                    const IdList & ids, const double phi, bool timeLike);
0126
0127 protected:
0128
0129   /**
0130    *   Get the couplings
0131    */
0132   void getCouplings(double & gvvv, const IdList & ids) const;
0133
0134 public:
0135
0136   /** @name Functions used by the persistent I/O system. */
0137   //@{
0138   /**
0139    * Function used to write out object persistently.
0140    * @param os the persistent output stream written to.
0141    */
0142   void persistentOutput(PersistentOStream & os) const;
0143
0144   /**
0145    * Function used to read in object persistently.
0146    * @param is the persistent input stream read from.
0147    * @param version the version number of the object when written.
0148    */
0149   void persistentInput(PersistentIStream & is, int version);
0150   //@}
0151
0152   /**
0153    * The standard Init function used to initialize the interfaces.
0154    * Called exactly once for each class by the class description system
0155    * before the main function starts or
0156    * when this class is dynamically loaded.
0157    */
0158   static void Init();
0159
0160 protected:
0161
0162   /** @name Clone Methods. */
0163   //@{
0164   /**
0165    * Make a simple clone of this object.
0166    * @return a pointer to the new object.
0167    */
0168   virtual IBPtr clone() const;
0169
0170   /** Make a clone of this object, possibly modifying the cloned object
0171    * to make it sane.
0172    * @return a pointer to the new object.
0173    */
0174   virtual IBPtr fullclone() const;
0175   //@}
0176
0177 protected:
0178
0179   /** @name Standard Interfaced functions. */
0180   //@{
0181   /**
0182    * Initialize this object after the setup phase before saving an
0183    * EventGenerator to disk.
0184    * @throws InitException if object could not be initialized properly.
0185    */
0186   virtual void doinit();
0187   //@}
0188
0189 private:
0190
0191   /**
0192    * The assignment operator is private and must never be called.
0193    * In fact, it should not even be implemented.
0194    */
0195   OneOneOneQEDSplitFn & operator=(const OneOneOneQEDSplitFn &) = delete;
0196
0197 private:
0198
0199   /**
0200    *  W^{\pm} -> W^{\pm} G couplings
0201    */
0202   double gWWG_;
0203
0204   /**
0205    * Pointer to the SM object.
0206    */
0207   tcHwSMPtr _theSM;
0208 };
0209
0210 }
0211
0212 #endif /* Herwig_OneOneOneQEDSplitFn_H */