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MEee2Higgs2SM.h
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// -*- C++ -*-
//
// MEee2Higgs2SM.h is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2019 The Herwig Collaboration
//
// Herwig is licenced under version 3 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef HERWIG_MEee2Higgs2SM_H
#define HERWIG_MEee2Higgs2SM_H
//
// This is the declaration of the MEee2Higgs2SM class.
//
#include "ThePEG/MatrixElement/ME2to2Base.h"
#include "Herwig/Models/StandardModel/StandardModel.h"
#include "Herwig/MatrixElement/ProductionMatrixElement.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
namespace Herwig {
using namespace ThePEG;
/**
* The MEee2Higgs2SM class implements the production of an \f$s\f$-channel
* Higgs in \f$e^+e^-\f$ collisions in order to allow easy tests of Higgs
* decays. It should not be used for physics studies.
*
* @see \ref MEee2Higgs2SMInterfaces "The interfaces"
* defined for MEee2Higgs2SM.
*/
class MEee2Higgs2SM: public ME2to2Base {
public:
/**
* The default constructor.
*/
inline MEee2Higgs2SM() : allowed_(0) {}
/** @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;
/**
* set up the spin correlations
*/
virtual void constructVertex(tSubProPtr sub);
//@}
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:
/** @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();
/**
* 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)
;
/**
* Return a vector of all pointers to Interfaced objects used in this
* object.
* @return a vector of pointers.
*/
virtual IVector getReferences();
//@}
private:
/**
* The matrix element
* @param fin The incoming spinor wavefunction
* @param ain The incoming spinorbar wavefunction
* @param fout The outgoing spinor bar wavefunction
* @param aout The outgoing spinor wavefunction
* @param me The spin averaged matrix element
*/
ProductionMatrixElement HelicityME(vector<SpinorWaveFunction> fin,
vector<SpinorBarWaveFunction> ain,
vector<SpinorBarWaveFunction> fout,
vector<SpinorWaveFunction> aout,double& me) const;
/**
* \f$H\to gg\f$ matrix element
* @param fin The incoming spinor wavefunction
* @param ain The incoming spinorbar wavefunction
* @param g1 Outgoing gluon wavefunction
* @param g2 Outgoing gluon wavefunction
* @param me The spin averaged matrix element
*/
ProductionMatrixElement ggME(vector<SpinorWaveFunction> fin,
vector<SpinorBarWaveFunction> ain,
vector<VectorWaveFunction> g1,
vector<VectorWaveFunction> g2,
double & me) const;
private:
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
MEee2Higgs2SM & operator=(const MEee2Higgs2SM &) = delete;
private:
/**
* Pointer to the Higgs fermion-antifermion vertex
*/
AbstractFFSVertexPtr FFHVertex_;
/**
* Pointer to Higgs-gluon-gluon vertex
*/
AbstractVVSVertexPtr HGGVertex_;
/**
* Allowed outgoing particles
*/
int allowed_;
/**
* Pointer to the Higgs ParticleData object
*/
PDPtr h0_;
};
}
#endif /* HERWIG_MEee2Higgs2SM_H */

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