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MEPP2WJet.h
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MEPP2WJet.h
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// -*- C++ -*-
#ifndef HERWIG_MEPP2WJet_H
#define HERWIG_MEPP2WJet_H
//
// This is the declaration of the MEPP2WJet class.
//
#include "Herwig++/MatrixElement/HwMEBase.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
#include "Herwig++/MatrixElement/ProductionMatrixElement.h"
#include "ThePEG/Helicity/Vertex/AbstractFFVVertex.fh"
namespace Herwig {
using namespace ThePEG;
using namespace ThePEG::Helicity;
/**
* The MEPP2WJet class implements the matrix element for the production of
* a W boson and a jet including the decay of the W.
*
* @see \ref MEPP2WJetInterfaces "The interfaces"
* defined for MEPP2WJet.
*/
class MEPP2WJet: public HwMEBase {
public:
/**
* The default constructor.
*/
MEPP2WJet();
/** @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;
/**
* 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;
/**
* 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:
/**
* Used internally by generateKinematics, after calculating the
* limits on cos(theta).
*/
double getCosTheta(double cthmin, double cthmax, const double r);
/**
* Matrix elements for the different subprocesses
*/
//@{
/**
* Matrix element for \f$q\bar{q}\to W^\pm g\f$.
* @param fin Spinors for incoming quark
* @param ain Spinors for incoming antiquark
* @param gout Polarization vectors for the outgoing gluon
* @param lm Spinors for outgoing lepton
* @param lp Spinors for outgoing antilepton
* @param me Whether or not to calculate the matrix element for spin correlations
**/
InvEnergy2 qqbarME(vector<SpinorWaveFunction> & fin,
vector<SpinorBarWaveFunction> & ain,
vector<VectorWaveFunction> & gout,
vector<SpinorBarWaveFunction> & lm,
vector<SpinorWaveFunction> & lp,
bool me=false) const;
/**
* Matrix element for \f$qg\to W^\pm q\f$.
* @param fin Spinors for incoming quark
* @param gin Polarization vectors for the incoming gluon
* @param fout Spinors for outgoing quark
* @param lm Spinors for outgoing lepton
* @param lp Spinors for outgoing antilepton
* @param me Whether or not to calculate the matrix element for spin correlations
**/
InvEnergy2 qgME(vector<SpinorWaveFunction> & fin,
vector<VectorWaveFunction> & gin,
vector<SpinorBarWaveFunction> & fout,
vector<SpinorBarWaveFunction> & lm,
vector<SpinorWaveFunction> & lp,
bool me=false) const;
/**
* Matrix element for \f$\bar{q}g\to W^\pm\bar{q}\f$.
* @param fin Spinors for incoming antiquark
* @param gin Polarization vectors for the incoming gluon
* @param fout Spinors for outgoing antiquark
* @param lm Spinors for outgoing lepton
* @param lp Spinors for outgoing antilepton
* @param me Whether or not to calculate the matrix element for spin correlations
**/
InvEnergy2 qbargME(vector<SpinorBarWaveFunction> & fin,
vector<VectorWaveFunction> & gin,
vector<SpinorWaveFunction> & fout,
vector<SpinorBarWaveFunction> & lm,
vector<SpinorWaveFunction> & lp,
bool me=false) const;
//@}
protected:
/** @name Clone Methods. */
//@{
/**
* Make a simple clone of this object.
* @return a pointer to the new object.
*/
virtual IBPtr clone() const { return new_ptr(*this); }
/** Make a clone of this object, possibly modifying the cloned object
* to make it sane.
* @return a pointer to the new object.
*/
virtual IBPtr fullclone() const { return new_ptr(*this); }
//@}
protected:
/** @name Standard Interfaced functions. */
//@{
/**
* Initialize this object after the setup phase before saving an
* EventGenerator to disk.
* @throws InitException if object could not be initialized properly.
*/
virtual void doinit();
//@}
private:
/**
* The static object used to initialize the description of this class.
* Indicates that this is a concrete class with persistent data.
*/
static ClassDescription<MEPP2WJet> initMEPP2WJet;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
MEPP2WJet & operator=(const MEPP2WJet &);
private:
/**
* Vertices for the helicity amplitude calculation
*/
//@{
/**
* Pointer to the W vertex
*/
AbstractFFVVertexPtr _theFFWVertex;
/**
* Pointer to the \f$qqg\f$ vertex
*/
AbstractFFVVertexPtr _theQQGVertex;
//@}
/**
* @name Pointers to the W ParticleData objects
*/
//@{
/**
* The \f$W^+\f$ data pointer
*/
tcPDPtr _wplus;
/**
* The \f$W^-\f$ data pointer
*/
tcPDPtr _wminus;
//@}
/**
* @name Switches to control the particles in the hard process
*/
//@{
/**
* Subprocesses to include
*/
unsigned int _process;
/**
* Allowed flavours for the incoming quarks
*/
unsigned int _maxflavour;
/**
* Which charge states to include
*/
unsigned int _plusminus;
/**
* W decay modes
*/
unsigned int _wdec;
/**
* Option for the treatment of the W off-shell effects
*/
unsigned int _widthopt;
//@}
/**
* Matrix element for spin correlations
*/
mutable ProductionMatrixElement _me;
/**
* Storage of the scale to avoid the need to recalculate
*/
Energy2 _scale;
/**
* Storage of the off-shell W mass to avoid the need to recalculate
*/
Energy2 _mw2;
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the
* base classes of MEPP2WJet. */
template <>
struct BaseClassTrait<Herwig::MEPP2WJet,1> {
/** Typedef of the first base class of MEPP2WJet. */
typedef Herwig::HwMEBase NthBase;
};
/** This template specialization informs ThePEG about the name of
* the MEPP2WJet class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::MEPP2WJet>
: public ClassTraitsBase<Herwig::MEPP2WJet> {
/** Return a platform-independent class name */
static string className() { return "Herwig::MEPP2WJet"; }
/**
* The name of a file containing the dynamic library where the class
* MEPP2WJet is implemented. It may also include several, space-separated,
* libraries if the class MEPP2WJet 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_MEPP2WJet_H */

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