libthepeg-dev 1.8.0-1.1 / usr / include / ThePEG / PDT / SimpleBaryonRemnantDecayer.h

// -*- C++ -*-
//
// SimpleBaryonRemnantDecayer.h is a part of ThePEG - Toolkit for HEP Event Generation
// Copyright (C) 1999-2011 Leif Lonnblad
//
// ThePEG is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef THEPEG_SimpleBaryonRemnantDecayer_H
#define THEPEG_SimpleBaryonRemnantDecayer_H
//
// This is the declaration of the SimpleBaryonRemnantDecayer class.
//

#include "ThePEG/PDT/RemnantDecayer.h"
#include "ThePEG/Handlers/ZGenerator.h"
#include "ThePEG/Handlers/FlavourGenerator.h"
#include "ThePEG/Utilities/VSelector.h"

namespace ThePEG {

/**
 * The SimpleBaryonRemnantDecayer class inherits from the
 * RemnantDecayer class and is able to decay RemnantParticles produced
 * by the SoftRemnantHandler class for the cases when a single parton
 * has been extracted from a baryon.
 *
 * @see \ref SimpleBaryonRemnantDecayerInterfaces "The interfaces"
 * defined for SimpleBaryonRemnantDecayer.
 */
class SimpleBaryonRemnantDecayer: public RemnantDecayer {

public:

  /** A pointer to a ZGenerator object. */
  typedef Ptr<ZGenerator>::pointer ZGPtr;
  /** A pointer to a FlavourGenerator object. */
  typedef Ptr<FlavourGenerator>::pointer FlGPtr;

public:

  /** @name Standard constructors and destructors. */
  //@{
  /**
   * The default constructor.
   */
  SimpleBaryonRemnantDecayer()
    : theMargin(1.0*GeV), useSpecialValence(false) {}

  /**
   * The copy constructor.
   */
  SimpleBaryonRemnantDecayer(const SimpleBaryonRemnantDecayer & x)
    : RemnantDecayer(x), theZGenerator(x.theZGenerator),
      theFlavourGenerator(x.theFlavourGenerator), theMargin(x.theMargin),
      useSpecialValence(x.useSpecialValence) {}

  /**
   * The destructor.
   */
  virtual ~SimpleBaryonRemnantDecayer();
  //@}

public:

  /** @name Virtual functions required by the RemnantDecayer class. */
  //@{
  /**
   * Check if this decayer can perfom the decay specified by the
   * given decay mode.
   * @param dm the DecayMode describing the decay.
   * @return true if this decayer can handle the given mode, otherwise false.
   */
  virtual bool accept(const DecayMode & dm) const;

  /**
   * Perform a decay for a given DecayMode and a given Particle
   * instance. This version allows the decaying particle to borrow
   * energy/momentum from its sublings in the current step. This will
   * be called by the standard DecayHandler if the needsFullStep()
   * function returns true.
   *
   * @param dm   the DecayMode describing the decay.
   * @param p    the Particle instance to be decayed.
   * @param step the current step in which to find possible siblings to
   *             shuffle energy with.
   * @return a ParticleVector containing the decay products.
   */
  virtual ParticleVector decay(const DecayMode & dm, const Particle & p,
			       Step & step) const;

  /**
   * Return true if this decayer can handle the extraction of the \a
   * extracted parton from the given \a particle.
   */
  virtual bool canHandle(tcPDPtr parent, tcPDPtr extracted) const;

  /**
   * Return true if this decayer can handle the extraction of the \a
   * extracted parton instance from the given \a particle instance. \a
   * pnew is the momentum of the resulting remnant. The default
   * version simply checks if the energy is positive.
   */
  virtual bool checkExtract(tcPPtr parent, tcPPtr extracted,
			    const LorentzMomentum & pnew) const;
  //@}

protected:

  /** @name Standard Interfaced functions. */
  //@{
  /**
   * Initialize this object after the setup phase before saving an
   * EventGenerator to disk.
   * @throws InitException if object could not be initialized properly.
   */
  virtual void doinit();

  /**
   * Return true if this object needs to be initialized before all
   * other objects because it needs to extract cuts from the event file.
   */
  virtual bool preInitialize() const;
  //@}

public:

  /** @name Functions used by the persistent I/O system. */
  //@{
  /**
   * Function used to write out object persistently.
   * @param os the persistent output stream written to.
   */
  void persistentOutput(PersistentOStream & os) const;

  /**
   * Function used to read in object persistently.
   * @param is the persistent input stream read from.
   * @param version the version number of the object when written.
   */
  void persistentInput(PersistentIStream & is, int version);
  //@}

  /**
   * The standard Init function used to initialize the interfaces.
   * Called exactly once for each class by the class description system
   * before the main function starts or
   * when this class is dynamically loaded.
   */
  static void Init();

public:

  /**
   * Warning Exception used when DIS kinematics was not respected.
   */
  struct NoDISRespect: public Exception {};

  /**
   * Exception thrown if the decay of a remnant was impossible.
   */
  struct DecayFailed: public Exception {};

protected:

  /**
   * Return a reference to the object responsible for generating
   * momentum fractions in case of more than one remnant.
   */
  ZGenerator & zGenerator() const { return *theZGenerator; }

  /**
   * Return a reference to the object responsible for handling the
   * flavour contents of a baryon.
   */
  FlavourGenerator & flavourGenerator() const { return *theFlavourGenerator; }

  /**
   * Return the energy margin to be added to the sum of the parent and
   * parton masses to determine if it is possible to construct the
   * remnants with the given (upper limit of the) virtuality of the
   * extracted parton.
   */
  Energy margin() const { return theMargin; }

  /**
   * If true an extracted valens quark will always give a di-quark remnant.
   */
  bool specialValence() const { return useSpecialValence; }

protected:

  /** @name Clone Methods. */
  //@{
  /**
   * Make a simple clone of this object.
   * @return a pointer to the new object.
   */
  virtual IBPtr clone() const;

  /** Make a clone of this object, possibly modifying the cloned object
   * to make it sane.
   * @return a pointer to the new object.
   */
  virtual IBPtr fullclone() const;
  //@}

protected:

  /**
   * Simple struct to store info about baryon quark and di-quark
   * constituents.
   */
  struct BaryonContent {
    /** The valence flavours of the corresponding baryon. */
    vector<int> flav;
    /** Different divisions into quark-diquark weighted by their
	respective probabilities. */
    VSelector< pair<int,int> > flavsel;
    /** -1 if the particle is an anti-particle. +1 otherwise. */
    int sign;
  };

  /**
   * Return info about baryon quark and di-quark constituents.
   */
  const BaryonContent & getBaryonInfo(tcPDPtr baryon) const;    

private:

  /**
   * The object responsible for generating momentum fractions in case
   * of more than one remnant.
   */
  ZGPtr theZGenerator;

  /**
   * The object responsible for handling the flavour contents of a
   * baryon.
   */
  FlGPtr theFlavourGenerator;

  /**
   * The energy margin to be added to the sum of the parent and parton
   * masses to determine if it is possible to construct the remnants
   * with the given (upper limit of the) virtuality of the extracted
   * parton.
   */
  Energy theMargin;

  /**
   * If true an extracted valens quark will always give a di-quark remnant.
   */
  bool useSpecialValence;

  /**
   * A map of info about baryon quark and di-quark constituents.
   */
  mutable map<tcPDPtr,BaryonContent> baryonmap;

private:

  /**
   * The static object used to initialize the description of this class.
   * Indicates that this is a concrete class with persistent data.
   */
  static ClassDescription<SimpleBaryonRemnantDecayer>
  initSimpleBaryonRemnantDecayer;

  /**
   * The assignment operator is private and must never be called.
   * In fact, it should not even be implemented.
   */
  SimpleBaryonRemnantDecayer & operator=(const SimpleBaryonRemnantDecayer &);

};

}

#include "ThePEG/Utilities/ClassTraits.h"

namespace ThePEG {

/** @cond TRAITSPECIALIZATIONS */

/** This template specialization informs ThePEG about the
 *  base classes of SimpleBaryonRemnantDecayer. */
template <>
struct BaseClassTrait<SimpleBaryonRemnantDecayer,1> {
  /** Typedef of the first base class of SimpleBaryonRemnantDecayer. */
  typedef RemnantDecayer NthBase;
};

/** This template specialization informs ThePEG about the name of the
 *  SimpleBaryonRemnantDecayer class and the shared object where it is
 *  defined. */
template <>
struct ClassTraits<SimpleBaryonRemnantDecayer>
  : public ClassTraitsBase<SimpleBaryonRemnantDecayer> {
  /** Return a platform-independent class name */
  static string className() { return "ThePEG::SimpleBaryonRemnantDecayer"; }
};

/** @endcond */

}

#endif /* THEPEG_SimpleBaryonRemnantDecayer_H */