Page MenuHomeHEPForge
Files F8724161

MEee2VectorMeson.h
No OneTemporary
Actions

MEee2VectorMeson.h
View Options

// -*- C++ -*-
//
// MEee2VectorMeson.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_MEee2VectorMeson_H
#define HERWIG_MEee2VectorMeson_H
//
// This is the declaration of the MEee2VectorMeson class.
//
#include "ThePEG/MatrixElement/MEBase.h"
#include "Herwig/PDT/GenericMassGenerator.fh"
#include "Herwig/MatrixElement/ProductionMatrixElement.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
namespace Herwig {
using namespace ThePEG;
using Helicity::SpinorWaveFunction;
using Helicity::SpinorBarWaveFunction;
using Helicity::VectorWaveFunction;
/**
* The MEee2VectorMeson class is designed to produce neutral vector mesons
* in \f$e^+e^-\f$ collisions and is primarily intended to test the hadronic
* decay package.
*
* @see \ref MEee2VectorMesonInterfaces "The interfaces"
* defined for MEee2VectorMeson.
*/
class MEee2VectorMeson: public MEBase {
public:
/**
* The default constructor.
*/
MEee2VectorMeson() : coupling_(0.0012), lineShape_(false)
{}
/** @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;
/**
* 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();
//@}
private:
/**
* Member to return the helicity amplitudes
*/
ProductionMatrixElement HelicityME(vector<SpinorWaveFunction> fin,
vector<SpinorBarWaveFunction> ain,
vector<VectorWaveFunction> vout,double& me) const;
private:
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
MEee2VectorMeson & operator=(const MEee2VectorMeson &) = delete;
private:
/**
* The vector meson being produced
*/
PDPtr vector_;
/**
* The coupling
*/
double coupling_;
/**
* Use the mass generator for the line shape
*/
bool lineShape_;
/**
* Pointer to the mass generator for the Higgs
*/
GenericMassGeneratorPtr massGen_;
};
}
#endif /* HERWIG_MEee2VectorMeson_H */

File Metadata

Mime Type
text/x-c++
Expires
Mon, Jan 20, 10:35 PM (1 d, 17 h)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
4214128
Default Alt Text
MEee2VectorMeson.h (6 KB)

Event Timeline