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MEPP2Higgs.h
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MEPP2Higgs.h
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// -*- C++ -*-
//
// MEPP2Higgs.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_MEPP2Higgs_H
#define HERWIG_MEPP2Higgs_H
//
// This is the declaration of the MEPP2Higgs class.
//
#include "ThePEG/MatrixElement/MEBase.h"
#include "ThePEG/Helicity/WaveFunction/ScalarWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
#include "ThePEG/Helicity/Vertex/AbstractFFSVertex.h"
#include "ThePEG/Helicity/Vertex/AbstractVVSVertex.h"
#include "Herwig++/PDT/SMHiggsMassGenerator.h"
#include "Herwig++/Models/StandardModel/StandardModel.h"
#include "Herwig++/MatrixElement/ProductionMatrixElement.h"
namespace Herwig {
using namespace ThePEG;
using namespace ThePEG::Helicity;
/**
* The MEPP2Higgs class implements the matrix element for the process
* pp->Higgs with different Higgs shape prescriptions (see details in hep-ph/9505211)
* and the NLL corrected Higgs width (see details in the FORTRAN HERWIG manual).
*
* @see \ref MEPP2HiggsInterfaces "The interfaces"
* defined for MEPP2Higgs.
*/
class MEPP2Higgs: public MEBase {
public:
/**
* The default constructor.
*/
MEPP2Higgs();
/**
* Return the matrix element for the kinematical configuation
* previously provided by the last call to setKinematics(). Uses
* me().
*/
virtual CrossSection dSigHatDR() const;
public:
/** @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;
/**
* 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 scale associated with the last set phase space point.
*/
virtual Energy2 scale() const;
/**
* The number of internal degrees of freedom used in the matrix
* element.
*/
virtual int nDim() 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:
/** @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:
/**
* The static object used to initialize the description of this class.
* Indicates that this is a concrete class with persistent data.
*/
static ClassDescription<MEPP2Higgs> initMEPP2Higgs;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
MEPP2Higgs & operator=(const MEPP2Higgs &);
//@}
/**
* Members to return the matrix elements for the different subprocesses
*/
//@{
/**
* Calculates the matrix element for the process g,g->h (via quark loops)
* @param g1 a vector of wave functions of the first incoming gluon
* @param g2 a vector of wave functions of the second incoming gluon
* @param calc Whether or not to calculate the matrix element for spin correlations
* @return the amlitude value.
*/
double ggME(vector<VectorWaveFunction> g1,
vector<VectorWaveFunction> g2,
ScalarWaveFunction &,
bool calc) const;
/**
* Calculates the matrix element for the process q,qbar->h
* @param fin a vector of quark spinors
* @param ain a vector of anti-quark spinors
* @param calc Whether or not to calculate the matrix element for spin correlations
* @return the amlitude value.
*/
double qqME(vector<SpinorWaveFunction> & fin,
vector<SpinorBarWaveFunction> & ain,
ScalarWaveFunction &,
bool calc) const;
//@}
private:
/**
* Defines the Higgs resonance shape
*/
unsigned int shapeopt;
/**
* The processes to be included (GG->H and/or qq->H)
*/
unsigned int processopt;
/**
* Minimum flavour of incoming quarks
*/
unsigned int minflavouropt;
/**
* Maximum flavour of incoming quarks
*/
unsigned int maxflavouropt;
/**
* Storage of the diagram weights for the \f$gg\to Hg\f$ subprocess
*/
mutable double diagwgt[3];
/**
* Matrix element for spin correlations
*/
ProductionMatrixElement _me;
/**
* Pointer to the H->2gluons vertex (used in gg->H)
*/
AbstractVVSVertexPtr hggvertex;
/**
* Pointer to the fermion-fermion Higgs vertex (used in qq->H)
*/
AbstractFFSVertexPtr ffhvertex;
/**
* Pointer to the Standard Model instance used in the class
*/
tcHwSMPtr theSM;
/**
* The mass generator for the Higgs
*/
SMHiggsMassGeneratorPtr _hmass;
/**
* On-shell mass for the higgs
*/
Energy _mh;
/**
* On-shell width for the higgs
*/
Energy _wh;
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the base classes of MEPP2Higgs. */
template <>
struct BaseClassTrait<Herwig::MEPP2Higgs,1> {
/** Typedef of the first base class of MEPP2Higgs. */
typedef MEBase NthBase;
};
/** This template specialization informs ThePEG about the name of
* the MEPP2Higgs class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::MEPP2Higgs>
: public ClassTraitsBase<Herwig::MEPP2Higgs> {
/** Return a platform-independent class name */
static string className() { return "Herwig::MEPP2Higgs"; }
/**
* The name of a file containing the dynamic library where the class
* MEPP2Higgs is implemented. It may also include several, space-separated,
* libraries if the class MEPP2Higgs 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_MEPP2Higgs_H */

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