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MEfftoVH.h
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// -*- C++ -*-
#ifndef HERWIG_MEfftoVH_H
#define HERWIG_MEfftoVH_H
//
// This is the declaration of the MEfftoVH class.
//
#include "DrellYanBase.h"
#include "ThePEG/Helicity/Vertex/AbstractFFVVertex.h"
#include "ThePEG/Helicity/Vertex/AbstractVVSVertex.h"
#include "Herwig++/MatrixElement/ProductionMatrixElement.h"
#include "Herwig++/PDT/GenericMassGenerator.h"
namespace Herwig {
using namespace ThePEG;
/**
* The MEfftoVH class is the base class for \f$f\bar{f}\to VH\f$ processes.
* This base class handles the phase-space integration while
* the inheriting classes implement the matrix element
*
* @see \ref MEfftoVHInterfaces "The interfaces"
* defined for MEfftoVH.
*/
class MEfftoVH: public DrellYanBase {
public:
/**
* The default constructor.
*/
MEfftoVH() : _shapeopt(2), _maxflavour(5), _mh(), _wh() {}
/** @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;
/**
* Set the typed and momenta of the incoming and outgoing partons to
* be used in subsequent calls to me() and colourGeometries()
* according to the associated XComb object. If the function is
* overridden in a sub class the new function must call the base
* class one first.
*/
virtual void setKinematics();
/**
* The number of internal degrees of freedom used in the matrix
* element.
*/
virtual int nDim() const;
/**
* Generate internal degrees of freedom given nDim() uniform
* random numbers in the interval \f$ ]0,1[ \f$. To help the phase space
* generator, the dSigHatDR should be a smooth function of these
* numbers, although this is not strictly necessary.
* @param r a pointer to the first of nDim() consecutive random numbers.
* @return true if the generation succeeded, otherwise false.
*/
virtual bool generateKinematics(const double * r);
/**
* Return the matrix element squared differential in the variables
* given by the last call to generateKinematics().
*/
virtual CrossSection dSigHatDR() 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:
/**
* Matrix element for \f$f\bar{f}\to V h^0\to f'\bar{f'} h^0\f$.
* @param fin Spinors for incoming fermion
* @param ain Spinors for incoming antifermion
* @param fout Spinors for incoming fermion
* @param aout Spinors for incoming antifermion
* @param me Whether or not to calculate the matrix element for spin correlations
*/
double helicityME(vector<SpinorWaveFunction> & fin ,
vector<SpinorBarWaveFunction> & ain ,
vector<SpinorBarWaveFunction> & fout,
vector<SpinorWaveFunction> & aout,
bool me) const;
/**
* Used internally by generateKinematics, after calculating the
* limits on cos(theta).
*/
virtual double getCosTheta(double cthmin, double cthmax, double r);
/**
* Access to the vector ParticleData objects
*/
//@{
/**
* Access to the \f$W^+\f$ data
*/
PDPtr WPlus() const { return _wplus; }
/**
* Access to the \f$W^-\f$ data
*/
PDPtr WMinus() const { return _wminus; }
/**
* Access to the \f$Z^0\f$ data
*/
PDPtr Z0() const { return _z0; }
/**
* Access to the higgs data
*/
PDPtr higgs() const { return _higgs; }
/**
* Set the higgs data
*/
void higgs(PDPtr in) {_higgs =in;}
//@}
/**
* Set the pointer to the vector-vector-Higgs vertex
*/
void setWWHVertex(AbstractVVSVertexPtr in) {
_vertexWWH = in;
}
/**
* Set the line shape treatment
*/
void lineShape(unsigned int in) {_shapeopt=in;}
/**
* Maximum flavour of the incoming partons
*/
unsigned int maxFlavour() const {return _maxflavour;}
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();
//@}
private:
/**
* The static object used to initialize the description of this class.
* Indicates that this is an abstract class with persistent data.
*/
static AbstractClassDescription<MEfftoVH> initMEfftoVH;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
MEfftoVH & operator=(const MEfftoVH &);
private:
/**
* Defines the Higgs resonance shape
*/
unsigned int _shapeopt;
/**
* The allowed flavours of the incoming quarks
*/
unsigned int _maxflavour;
/**
* The intermediate vector bosons
*/
//@{
/**
* \f$W^+\f$
*/
PDPtr _wplus;
/**
* \f$W^-\f$
*/
PDPtr _wminus;
/**
* \f$Z^0\f$
*/
PDPtr _z0;
/**
* The higgs bosom
*/
PDPtr _higgs;
//@}
/**
* The vertices for the calculation of the matrix element
*/
//@{
/**
* Vertex for fermion-fermion-W
*/
AbstractFFVVertexPtr _vertexFFW;
/**
* Vertex for fermion-fermion-Z
*/
AbstractFFVVertexPtr _vertexFFZ;
/**
* Vertex for vector-vector-Higgs
*/
AbstractVVSVertexPtr _vertexWWH;
//@}
/**
* On-shell mass for the higgs
*/
Energy _mh;
/**
* On-shell width for the higgs
*/
Energy _wh;
/**
* The mass generator for the Higgs
*/
GenericMassGeneratorPtr _hmass;
/**
* Matrix element for spin correlations
*/
ProductionMatrixElement _me;
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the
* base classes of MEfftoVH. */
template <>
struct BaseClassTrait<Herwig::MEfftoVH,1> {
/** Typedef of the first base class of MEfftoVH. */
typedef Herwig::DrellYanBase NthBase;
};
/** This template specialization informs ThePEG about the name of
* the MEfftoVH class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::MEfftoVH>
: public ClassTraitsBase<Herwig::MEfftoVH> {
/** Return a platform-independent class name */
static string className() { return "Herwig::MEfftoVH"; }
};
/** @endcond */
}
#endif /* HERWIG_MEfftoVH_H */

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