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// -*- C++ -*-
//
// VVVTVertex.h is a part of ThePEG - Toolkit for HEP Event Generation
// Copyright (C) 2003-2011 Peter Richardson, Leif Lonnblad
//
// ThePEG is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef ThePEG_VVVTVertex_H
#define ThePEG_VVVTVertex_H
//
// This is the declaration of the VVVTVertex class.
//
#include "ThePEG/Helicity/Vertex/AbstractVVVTVertex.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/TensorWaveFunction.h"
#include "VVVTVertex.fh"
namespace ThePEG {
namespace Helicity {
/** \ingroup Helicity
*
* The VVTVertex class is the implementation of the
* vector-vector-vector-tensor vertex.
* It inherits from the AbstractVVVTVertex class for the storage of the particles
* interacting at the vertex and implements the helicity amplitude calculations.
*
* All implementations of this vertex should inherit from it and implement the
* virtual setCoupling member.
*
* The vertex has the form
* \f[
* g\frac\kappa2f^{abc}\left[
* C_{\mu\nu,\rho\sigma}(k_1-k_2)_\lambda+C_{\mu\nu,\rho\lambda}(k_3-k_1)_\sigma
* +C_{\mu\nu,\sigma\lambda}(k_2-k_3)_\rho+F_{\mu\nu,\rho\sigma\lambda}
* \right]\epsilon_1^\rho\epsilon^\sigma_2\epsilon^\lambda_3
* \epsilon^{\mu\nu}_4
* \f]
* where
* -\f$C_{\mu\nu,\rho\sigma}=g_{\mu\rho}g_{\nu\sigma}+g_{\mu\sigma}g_{\nu\rho}
* -g_{\mu\nu}g_{\rho\sigma}\f$
* -\f$F_{\mu\nu,\rho\sigma\lambda} =
* g_{\mu\rho}g_{\sigma\lambda}(k_2-k_3)_\nu
* +g_{\mu\sigma}g_{\rho\lambda}(k_3-k_1)_\nu
* +g_{\mu\lambda}g_{\rho\sigma}(k_1-k_2)_\nu+(\mu\leftrightarrow\nu)
* \f$
*
* @see AbstractVVVTVertex
*/
class VVVTVertex: public AbstractVVVTVertex {
public:
/**
* Standard Init function used to initialize the interfaces.
*/
static void Init();
public:
/**
* Members to calculate the helicity amplitude expressions for vertices
* and off-shell particles.
*/
//@{
/**
* Evalulate the vertex.
* @param q2 The scale \f$q^2\f$ for the coupling at the vertex.
* @param vec1 The wavefunction for the first vector.
* @param vec2 The wavefunction for the second vector.
* @param vec3 The wavefunction for the third vector.
* @param ten4 The wavefunction for the tensor.
*/
Complex evaluate(Energy2 q2,const VectorWaveFunction & vec1,
const VectorWaveFunction & vec2,
const VectorWaveFunction & vec3, const TensorWaveFunction & ten4);
/**
* Evaluate the off-shell tensor coming from the vertex.
* @param q2 The scale \f$q^2\f$ for the coupling at the vertex.
* @param iopt Option of the shape of the Breit-Wigner for the off-shell tensor.
* @param out The ParticleData pointer for the off-shell tensor.
* @param vec1 The wavefunction for the first vector.
* @param vec2 The wavefunction for the second vector.
* @param vec3 The wavefunction for the third vector.
* @param mass The mass of the off-shell particle if not taken from the ParticleData
* object
* @param width The width of the off-shell particle if not taken from the ParticleData
* object
*/
TensorWaveFunction evaluate(Energy2 q2,int iopt, tcPDPtr out,
const VectorWaveFunction & vec1,
const VectorWaveFunction & vec2,
const VectorWaveFunction & vec3,
Energy mass=-GeV, Energy width=-GeV);
/**
* Evaluate the off-shell vector coming from the vertex.
* @param q2 The scale \f$q^2\f$ for the coupling at the vertex.
* @param iopt Option of the shape of the Breit-Wigner for the off-shell vector.
* @param out The ParticleData pointer for the off-shell vector.
* @param vec1 The wavefunction for the first vector.
* @param vec2 The wavefunction for the second vector.
* @param ten4 The wavefunction for the tensor.
* @param mass The mass of the off-shell particle if not taken from the ParticleData
* object
* @param width The width of the off-shell particle if not taken from the ParticleData
* object
*/
VectorWaveFunction evaluate(Energy2 q2,int iopt, tcPDPtr out,
const VectorWaveFunction & vec1,
const VectorWaveFunction & vec2,
const TensorWaveFunction & ten4,
Energy mass=-GeV, Energy width=-GeV);
//@}
/**
* Calculate the couplings. This method is virtual and must be implemented in
* classes inheriting from this.
* @param q2 The scale \f$q^2\f$ for the coupling at the vertex.
* @param part1 The ParticleData pointer for the first particle.
* @param part2 The ParticleData pointer for the second particle.
* @param part3 The ParticleData pointer for the third particle.
* @param part4 The ParticleData pointer for the fourth particle.
*/
virtual void setCoupling(Energy2 q2,tcPDPtr part1,tcPDPtr part2,
tcPDPtr part3, tcPDPtr part4)=0;
private:
/**
* Describe an abstract base class with persistent data.
*/
static AbstractNoPIOClassDescription<VVVTVertex> initVVVTVertex;
/**
* Private and non-existent assignment operator.
*/
VVVTVertex & operator=(const VVVTVertex &);
};
}
/** @cond TRAITSPECIALIZATIONS */
/**
* The following template specialization informs ThePEG about the
* base class of VVVTVertex.
*/
template <>
struct BaseClassTrait<ThePEG::Helicity::VVVTVertex,1> {
/** Typedef of the base class of VVVTVertex. */
typedef ThePEG::Helicity::AbstractVVVTVertex NthBase;
};
/**
* The following template specialization informs ThePEG about the
* name of this class and the shared object where it is defined.
*/
template <>
struct ClassTraits<ThePEG::Helicity::VVVTVertex>
: public ClassTraitsBase<ThePEG::Helicity::VVVTVertex> {
/**
* Return the class name.
*/
static string className() { return "ThePEG::VVVTVertex"; }
};
/** @endcond */
}
#endif /* ThePEG_VVVTVertex_H */

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