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SMHiggsWidthGenerator.h
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SMHiggsWidthGenerator.h
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// -*- C++ -*-
//
// SMHiggsWidthGenerator.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_SMHiggsWidthGenerator_H
#define HERWIG_SMHiggsWidthGenerator_H
//
// This is the declaration of the SMHiggsWidthGenerator class.
//
#include "ThePEG/PDT/WidthGenerator.h"
#include "SMHiggsWidthGenerator.fh"
namespace Herwig {
using namespace ThePEG;
/**
* Typedef to define a DecayMoap
*/
typedef Selector<tDMPtr> DecayMap;
/**
* The SMHiggsWidthGenerator class calculates the width for the Standard Model Higgs
* boson.
*
* @see \ref SMHiggsWidthGeneratorInterfaces "The interfaces"
* defined for SMHiggsWidthGenerator.
*/
class SMHiggsWidthGenerator: public WidthGenerator {
public:
/**
* The default constructor.
*/
inline SMHiggsWidthGenerator();
/** @name Virtual functions to be overridden from based class */
//@{
/**
* Return true if this object can be used for the given particle
* type with the given decay map.
*/
virtual bool accept(const ParticleData &) const;
/**
* Given a particle type and a mass of an instance of that particle
* type, calculate a width.
*/
virtual Energy width(const ParticleData &, Energy m) const;
/**
* Return decay map for the given particle type.
*/
virtual DecayMap rate(const ParticleData &) const;
/**
* Return a decay map for a given Particle instance.
*/
virtual DecayMap rate(const Particle &);
//@}
/**
* Return the total width and the sum of the partial widths for
* modes which are used
*/
pair<Energy,Energy> width(Energy, const ParticleData &) const;
/**
* Calculate the partial width for a given mode
* @param mH The Higgs masses
* @param imode The decay mode
*/
Energy partialWidth(Energy mH,unsigned int imode) const;
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;
/** 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;
//@}
protected:
/** @name Routines to calculate Higgs width. */
//@{
/**
* Calculates the double Breit-Wigner Integral a-la FORTRAN HERWIG.
* It is used in NLL corrected Higgs width for H->WW/ZZ,
* x = (M_V/M_H)^2, y=M_V*G_V/(M_H)^2, where M_V/G_V - V-boson mass/width
* @return the integral value.
*/
double HwDoubleBW(double x, double y) const;
/**
* Calculate a loop function for the triangle vertex GGH/AAH
* @return the loop function value as a complex number
*/
Complex HwW2(double tau) const;
//@}
/**
* Return the branching ratios at the given scale
* @param scale The off shell-mass of the Higgs
*/
DecayMap branching(Energy scale, const ParticleData &) const;
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<SMHiggsWidthGenerator> initSMHiggsWidthGenerator;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
SMHiggsWidthGenerator & operator=(const SMHiggsWidthGenerator &);
private:
/**
* Type of the Higgs width used (options: fixed, LO running, NLL corrected running)
*/
unsigned int _widthopt;
/**
* Number of times the width the Higgs is allowed to be off-shell
*/
double _offshell;
/**
* Particle properties extracged at initialization
*/
//@{
/**
* Mass of the W boson
*/
Energy _mw;
/**
* Mass of the Z boson
*/
Energy _mz;
/**
* Width of the W boson
*/
Energy _gamw;
/**
* Width of the Z boson
*/
Energy _gamz;
/**
* Masses of the quarks
*/
vector<Energy> _qmass;
/**
* Masses of the leptons
*/
vector<Energy> _lmass;
/**
* \f$\sin^2\theta_W\f$
*/
double _sw2;
/**
* The \f$C_A\f$ colour factor
*/
double _ca;
/**
* The \f$C_F\f$ colour factor
*/
double _cf;
//@}
/**
* Storage of parameters for speed
*/
//@{
/**
* The last scale
*/
mutable Energy _qlast;
/**
* \f$\Lambda_{\rm QCD}\f$
*/
mutable Energy _lambdaQCD;
/**
* The electromagnetic coupling
*/
mutable double _alphaEM;
/**
* The strong coupling
*/
mutable double _alphaS;
/**
* Correction factor for \f$H\to q\bar{q}\f$
*/
mutable double _cd;
/**
* Fermi constant
*/
mutable Energy2 _gfermiinv;
/**
* The anomalous dimension for \f$H\to q\bar{q}\f$
*/
mutable double _gam0;
/**
* The \f$\beta\f$ function coefficient for \f$H\to q\bar{q}\f$
*/
mutable double _beta0;
//@}
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the
* base classes of SMHiggsWidthGenerator. */
template <>
struct BaseClassTrait<Herwig::SMHiggsWidthGenerator,1> {
/** Typedef of the first base class of SMHiggsWidthGenerator. */
typedef WidthGenerator NthBase;
};
/** This template specialization informs ThePEG about the name of
* the SMHiggsWidthGenerator class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::SMHiggsWidthGenerator>
: public ClassTraitsBase<Herwig::SMHiggsWidthGenerator> {
/** Return a platform-independent class name */
static string className() { return "Herwig::SMHiggsWidthGenerator"; }
};
/** @endcond */
}
#include "SMHiggsWidthGenerator.icc"
#endif /* HERWIG_SMHiggsWidthGenerator_H */

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