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MEPP2QQ.h
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// -*- C++ -*-
//
// MEPP2QQ.h is a part of Herwig++ - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2007 The Herwig Collaboration
//
// Herwig++ is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef HERWIG_MEPP2QQ_H
#define HERWIG_MEPP2QQ_H
//
// This is the declaration of the MEPP2QQ class.
//
#include "Herwig++/MatrixElement/HwME2to2Base.h"
#include "Herwig++/MatrixElement/ProductionMatrixElement.h"
#include "ThePEG/Helicity/Vertex/AbstractFFVVertex.h"
#include "ThePEG/Helicity/Vertex/AbstractVVVVertex.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
namespace Herwig {
using namespace ThePEG;
using namespace ThePEG::Helicity;
/**
* The MEPP2QQ class implements the production of a heavy quark-antiquark
* pair via QCD.
*
* @see \ref MEPP2QQInterfaces "The interfaces"
* defined for MEPP2QQ.
*/
class MEPP2QQ: public HwME2to2Base {
public:
/**
* The default constructor.
*/
MEPP2QQ();
/** @name Virtual functions required by the MEBase class. */
//@{
/**
* Return the order in \f$\alpha_S\f$ in which this matrix
* element is given.
*/
virtual unsigned int orderInAlphaS() const;
/**
* Return the order in \f$\alpha_{EW}\f$ in which this matrix
* element is given.
*/
virtual unsigned int orderInAlphaEW() const;
/**
* The matrix element for the kinematical configuration
* previously provided by the last call to setKinematics(), suitably
* scaled by sHat() to give a dimension-less number.
* @return the matrix element scaled with sHat() to give a
* dimensionless number.
*/
virtual double me2() const;
/**
* Return the scale associated with the last set phase space point.
*/
virtual Energy2 scale() const;
/**
* Add all possible diagrams with the add() function.
*/
virtual void getDiagrams() const;
/**
* Get diagram selector. With the information previously supplied with the
* setKinematics method, a derived class may optionally
* override this method to weight the given diagrams with their
* (although certainly not physical) relative probabilities.
* @param dv the diagrams to be weighted.
* @return a Selector relating the given diagrams to their weights.
*/
virtual Selector<DiagramIndex> diagrams(const DiagramVector & dv) const;
/**
* Return a Selector with possible colour geometries for the selected
* diagram weighted by their relative probabilities.
* @param diag the diagram chosen.
* @return the possible colour geometries weighted by their
* relative probabilities.
*/
virtual Selector<const ColourLines *>
colourGeometries(tcDiagPtr diag) const;
/**
* Construct the vertex of spin correlations.
*/
virtual void constructVertex(tSubProPtr);
//@}
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();
protected:
/**
* Members to calculate the matrix elements
*/
//@{
/**
* Matrix element for \f$gg\to q\bar{q}\f$
* @param g1 The wavefunctions for the first incoming gluon
* @param g2 The wavefunctions for the second incoming gluon
* @param q The wavefunction for the outgoing quark
* @param qbar The wavefunction for the outgoing antiquark
* @param flow The colour flow
*/
double gg2qqbarME(vector<VectorWaveFunction> &g1,vector<VectorWaveFunction> &g2,
vector<SpinorBarWaveFunction> & q,vector<SpinorWaveFunction> & qbar,
unsigned int flow) const;
/**
* Matrix element for \f$q\bar{q}\to q\bar{q}\f$
* @param q1 The wavefunction for the incoming quark
* @param q2 The wavefunction for the incoming antiquark
* @param q3 The wavefunction for the outgoing quark
* @param q4 The wavefunction for the outgoing antiquark
* @param flow The colour flow
*/
double qqbar2qqbarME(vector<SpinorWaveFunction> & q1,
vector<SpinorBarWaveFunction> & q2,
vector<SpinorBarWaveFunction> & q3,
vector<SpinorWaveFunction> & q4,
unsigned int flow) const;
//@}
protected:
/** @name Clone Methods. */
//@{
/**
* Make a simple clone of this object.
* @return a pointer to the new object.
*/
inline virtual IBPtr clone() const { return new_ptr(*this); }
/** Make a clone of this object, possibly modifying the cloned object
* to make it sane.
* @return a pointer to the new object.
*/
inline virtual IBPtr fullclone() const { return new_ptr(*this); }
//@}
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() throw(InitException);
/**
* Rebind pointer to other Interfaced objects. Called in the setup phase
* after all objects used in an EventGenerator has been cloned so that
* the pointers will refer to the cloned objects afterwards.
* @param trans a TranslationMap relating the original objects to
* their respective clones.
* @throws RebindException if no cloned object was found for a given
* pointer.
*/
virtual void rebind(const TranslationMap & trans)
throw(RebindException);
/**
* Return a vector of all pointers to Interfaced objects used in this
* object.
* @return a vector of pointers.
*/
virtual IVector getReferences();
//@}
private:
/**
* The static object used to initialize the description of this class.
* Indicates that this is a concrete class with persistent data.
*/
static ClassDescription<MEPP2QQ> initMEPP2QQ;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
MEPP2QQ & operator=(const MEPP2QQ &);
private:
/**
* Vertices needed to compute the diagrams
*/
//@{
/**
* \f$ggg\f$ vertex
*/
AbstractVVVVertexPtr _gggvertex;
/**
* \f$q\bar{q}g\f$ vertex
*/
AbstractFFVVertexPtr _qqgvertex;
//@}
/**
* Quark Flavour
*/
unsigned int _quarkflavour;
/**
* Processes to include
*/
unsigned int _process;
/**
* Option for the treatment of bottom and lighter
* quark masses
*/
unsigned int _bottomopt;
/**
* Option for the treatment of top quark masses
*/
unsigned int _topopt;
/**
* Colour flow
*/
mutable unsigned int _flow;
/**
* Diagram
*/
mutable unsigned int _diagram;
/**
* Matrix element
*/
mutable ProductionMatrixElement _me;
/**
* ParticleData objects of the partons
*/
//@{
/**
* The gluon
*/
PDPtr _gluon;
/**
* the quarks
*/
vector<PDPtr> _quark;
/**
* the antiquarks
*/
vector<PDPtr> _antiquark;
//@}
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the
* base classes of MEPP2QQ. */
template <>
struct BaseClassTrait<Herwig::MEPP2QQ,1> {
/** Typedef of the first base class of MEPP2QQ. */
typedef Herwig::HwME2to2Base NthBase;
};
/** This template specialization informs ThePEG about the name of
* the MEPP2QQ class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::MEPP2QQ>
: public ClassTraitsBase<Herwig::MEPP2QQ> {
/** Return a platform-independent class name */
static string className() { return "Herwig::MEPP2QQ"; }
/**
* The name of a file containing the dynamic library where the class
* MEPP2QQ is implemented. It may also include several, space-separated,
* libraries if the class MEPP2QQ depends on other classes (base classes
* excepted). In this case the listed libraries will be dynamically
* linked in the order they are specified.
*/
static string library() { return "HwMEHadron.so"; }
};
/** @endcond */
}
#endif /* HERWIG_MEPP2QQ_H */

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