Herwig/Decay/HwDecayHandler.h

0001 // -*- C++ -*-
0002 //
0003 // HwDecayHandler.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_HwDecayHandler_H
0010 #define HERWIG_HwDecayHandler_H
0011 //
0012 // This is the declaration of the HwDecayHandler class.
0013 //
0014 #include "ThePEG/Handlers/DecayHandler.h"
0015 #include "ThePEG/EventRecord/Particle.h"
0016
0017
0018 namespace Herwig {
0019 using namespace ThePEG;
0020
0021 /** \ingroup Decay
0022  * The <code>HwDecayHandler</code> is the Herwig decay handler which
0023  *  administers the decays of unstable particles in Herwig. It
0024  * is derived from ThePEG::DecayHandler and includes a different handle
0025  * method in order to simulate decays including spin correlations.
0026  *
0027  * The handle method decays all particles in the current step, including
0028  * spin correlations. Another feature of the DecayHandler is that it correctly
0029  * handles mutlistep decays where a Decayer supplys intermediate decay products
0030  * in addition to the outgoing particles.
0031  *
0032  * @see ThePEG::StepHandler
0033  * @see ThePEG::CollisionHandler
0034  * @see ThePEG::SubProcessHandler
0035  * @see ThePEG::DecayHandler
0036  *
0037  */
0038
0039 class HwDecayHandler: public DecayHandler {
0040
0041 public:
0042
0043   /**
0044    * Default constructor
0045    */
0046   HwDecayHandler()  : DecayHandler(), _newstep(true)
0047   {}
0048
0049 public:
0050
0051   /**
0052    * Look through all \a tagged particled and decay all unstable ones.
0053    * @param eh the EventHandler in charge of the generation.
0054    * @param tagged the vector of particles to consider. If empty, all
0055    * final state particles in the current Step is considered.
0056    * @param hint a possible Hint which is ignored in this implementation.
0057    */
0058   virtual void handle(EventHandler & eh, const tPVector & tagged,
0059               const Hint & hint)
0060    ;
0061
0062   /**
0063    * Perform the decay of one unstable particle.
0064    * @param parent the particle to be decayed.
0065    * @param s the Step where decay products are inserted.
0066    * @throws Veto if the Handler requires the current step to be discarded.
0067    * @throws Exception if something goes wrong.
0068    */
0069   virtual void performDecay(tPPtr parent, Step & s) const
0070    ;
0071
0072   /**
0073    * add the decay products of in intermediate particle produced in a decay
0074    * @param parent the particle which has been decayed.
0075    * @param s the Step where decay products are inserted.
0076    * @throws Veto if the Handler requires the current step to be discarded.
0077    * @throws Exception if something goes wrong.
0078    */
0079   void addDecayedParticle(tPPtr parent, Step & s) const
0080    ;
0081
0082   /**
0083    * Standard Init function
0084    */
0085   static void Init();
0086
0087 public:
0088
0089   /** @name Functions used by the persistent I/O system. */
0090   //@{
0091   /**
0092    * Function used to write out object persistently.
0093    * @param os the persistent output stream written to.
0094    */
0095   void persistentOutput(PersistentOStream & os) const;
0096
0097   /**
0098    * Function used to read in object persistently.
0099    * @param is the persistent input stream read from.
0100    * @param version the version number of the object when written.
0101    */
0102   void persistentInput(PersistentIStream & is, int version);
0103   //@}
0104
0105 protected:
0106
0107   /** @name Clone Methods. */
0108   //@{
0109   /**
0110    * Make a simple clone of this object.
0111    * @return a pointer to the new object.
0112    */
0113   virtual IBPtr clone() const {return new_ptr(*this);}
0114
0115   /** Make a clone of this object, possibly modifying the cloned object
0116    * to make it sane.
0117    * @return a pointer to the new object.
0118    */
0119   virtual IBPtr fullclone() const {return new_ptr(*this);}
0120   //@}
0121
0122 protected:
0123
0124   /** @name Standard Interfaced functions. */
0125   //@{
0126   /**
0127    * Initialize this object after the setup phase before saving an
0128    * EventGenerator to disk.
0129    * @throws InitException if object could not be initialized properly.
0130    */
0131   virtual void doinit();
0132   //@}
0133
0134 protected:
0135
0136   /**
0137    *  Develop a stable particle
0138    */
0139   void develop(tPPtr particle) const {
0140     tcSpinPtr hwspin = particle->spinInfo();
0141     if ( hwspin )
0142       hwspin->develop();
0143   }
0144
0145 private:
0146
0147   /**
0148    *  Private and non-existent assignment operator.
0149    */
0150   HwDecayHandler & operator=(const HwDecayHandler &) = delete;
0151
0152 private:
0153
0154   /**
0155    *  Option for adding particles in a new Step
0156    */
0157   bool _newstep;
0158
0159   /**
0160    *  Particles which should not be decayed
0161    */
0162   set<tcPDPtr> _excluded;
0163
0164   /**
0165    *  Vector to fill the set as an interface
0166    */
0167   vector<PDPtr> _excludedVector;
0168
0169 };
0170 }
0171
0172 #endif /* HERWIG_HwDecayHandler_H */