Decay/General/TSSDecayer.h

0001 // -*- C++ -*-
0002 //
0003 // TSSDecayer.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_TSSDecayer_H
0010 #define HERWIG_TSSDecayer_H
0011 //
0012 // This is the declaration of the TSSDecayer class.
0013 //
0014
0015 #include "GeneralTwoBodyDecayer.h"
0016 #include "ThePEG/Repository/EventGenerator.h"
0017 #include "ThePEG/Helicity/Vertex/Tensor/SSTVertex.h"
0018
0019 namespace Herwig {
0020 using namespace ThePEG;
0021 using Helicity::SSTVertexPtr;
0022
0023 /** \ingroup Decay
0024  * The TSSDecayer class implements the decay of a tensor
0025  * to 2 scalars in a general model. It holds an SSTVertex pointer
0026  * that must be typecast from the VertexBase pointer held in
0027  * GeneralTwoBodyDecayer. It implents the virtual functions me2() and
0028  * partialWidth().
0029  *
0030  * @see GeneralTwoBodyDecayer
0031  */
0032 class TSSDecayer: public GeneralTwoBodyDecayer {
0033
0034 public:
0035
0036   /**
0037    * The default constructor.
0038    */
0039   TSSDecayer() {}
0040
0041 public:
0042
0043   /** @name Virtual functions required by the Decayer class. */
0044   //@{
0045   /**
0046    * Return the matrix element squared for a given mode and phase-space channel.
0047    * @param ichan The channel we are calculating the matrix element for.
0048    * @param part The decaying Particle.
0049    * @param outgoing The particles produced in the decay
0050    * @param momenta  The momenta of the particles produced in the decay
0051    * @param meopt Option for the calculation of the matrix element
0052    * @return The matrix element squared for the phase-space configuration.
0053    */
0054   double me2(const int ichan,const Particle & part,
0055          const tPDVector & outgoing,
0056          const vector<Lorentz5Momentum> & momenta,
0057          MEOption meopt) const;
0058
0059   /**
0060    *   Construct the SpinInfos for the particles produced in the decay
0061    */
0062   virtual void constructSpinInfo(const Particle & part,
0063                  ParticleVector outgoing) const;
0064
0065   /**
0066    * Function to return partial Width
0067    * @param inpart The decaying particle.
0068    * @param outa One of the decay products.
0069    * @param outb The other decay product.
0070    */
0071   virtual Energy partialWidth(PMPair inpart, PMPair outa,
0072                   PMPair outb) const;
0073
0074   /**
0075    *  Set the information on the decay
0076    */
0077   virtual void setDecayInfo(PDPtr incoming, PDPair outgoing,
0078                 vector<VertexBasePtr>,
0079                 map<ShowerInteraction,VertexBasePtr> &,
0080                 const vector<map<ShowerInteraction,VertexBasePtr> > &,
0081                 map<ShowerInteraction,VertexBasePtr>);
0082   //@}
0083
0084 public:
0085
0086   /** @name Functions used by the persistent I/O system. */
0087   //@{
0088   /**
0089    * Function used to write out object persistently.
0090    * @param os the persistent output stream written to.
0091    */
0092   void persistentOutput(PersistentOStream & os) const;
0093
0094   /**
0095    * Function used to read in object persistently.
0096    * @param is the persistent input stream read from.
0097    * @param version the version number of the object when written.
0098    */
0099   void persistentInput(PersistentIStream & is, int version);
0100   //@}
0101
0102   /**
0103    * The standard Init function used to initialize the interfaces.
0104    * Called exactly once for each class by the class description system
0105    * before the main function starts or
0106    * when this class is dynamically loaded.
0107    */
0108   static void Init();
0109
0110 protected:
0111
0112   /** @name Clone Methods. */
0113   //@{
0114   /**
0115    * Make a simple clone of this object.
0116    * @return a pointer to the new object.
0117    */
0118   virtual IBPtr clone() const;
0119
0120   /** Make a clone of this object, possibly modifying the cloned object
0121    * to make it sane.
0122    * @return a pointer to the new object.
0123    */
0124   virtual IBPtr fullclone() const;
0125   //@}
0126
0127 private:
0128
0129   /**
0130    * The assignment operator is private and must never be called.
0131    * In fact, it should not even be implemented.
0132    */
0133   TSSDecayer & operator=(const TSSDecayer &) = delete;
0134
0135 private:
0136
0137   /**
0138    *  Abstract pointer to AbstractSSTVertex
0139    */
0140   vector<AbstractSSTVertexPtr> vertex_;
0141
0142   /**
0143    * Pointer to the perturbative vertex
0144    */
0145   vector<SSTVertexPtr> perturbativeVertex_;
0146
0147   /**
0148    *  Spin density matrix
0149    */
0150   mutable RhoDMatrix rho_;
0151
0152   /**
0153    *  Polarization tensors of the decaying particle
0154    */
0155   mutable vector<Helicity::TensorWaveFunction> tensors_;
0156 };
0157
0158 }
0159
0160 #endif /* HERWIG_TSSDecayer_H */