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ShowerAlphaQCD.h
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ShowerAlphaQCD.h
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// -*- C++ -*-
#ifndef HERWIG_ShowerAlphaQCD_H
#define HERWIG_ShowerAlphaQCD_H
//
// This is the declaration of the ShowerAlphaQCD class.
//
#include "ShowerAlpha.h"
#include "ShowerIndex.h"
#include "ShowerAlphaQCD.fh"
namespace Herwig {
using namespace ThePEG;
/** \ingroup Shower
*
* This concrete class provides the definition of the
* pure virtual function value() and overestimateValue() for the
* strong coupling.
*
* @see ShowerAlpha
*
* @see \ref ShowerAlphaQCDInterfaces "The interfaces"
* defined for ShowerAlphaQCD.
*/
class ShowerAlphaQCD: public ShowerAlpha {
public:
/** @name Standard constructors and destructors. */
//@{
/**
* The default constructor.
*/
inline ShowerAlphaQCD();
/**
* The copy constructor.
*/
inline ShowerAlphaQCD(const ShowerAlphaQCD &);
/**
* The destructor.
*/
virtual ~ShowerAlphaQCD();
//@}
public:
/**
* Methods to return the coupling
*/
//@{
/**
* It returns the running coupling value evaluated at the input scale
* multiplied by the scale factor scaleFactor().
* @param scale The scale
* @return The coupling
*/
virtual double value(const Energy2 scale);
/**
* It returns the running coupling value evaluated at the input scale
* multiplied by the scale factor scaleFactor().
*/
virtual double overestimateValue();
//@}
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 Standard Interfaced functions. */
//@{
/**
* Check sanity of the object during the setup phase.
*/
inline virtual void doupdate() throw(UpdateException);
/**
* Initialize this object after the setup phase before saving an
* EventGenerator to disk.
* @throws InitException if object could not be initialized properly.
*/
inline virtual void doinit() throw(InitException);
/**
* Initialize this object. Called in the run phase just before
* a run begins.
*/
inline virtual void doinitrun();
/**
* Finalize this object. Called in the run phase just after a
* run has ended. Used eg. to write out statistics.
*/
inline virtual void dofinish();
/**
* Rebind pointer to other Interfaced objects. Called in the setup phase
* after all objects used in an EventGenerator has been cloned so that
* the pointers will refer to the cloned objects afterwards.
* @param trans a TranslationMap relating the original objects to
* their respective clones.
* @throws RebindException if no cloned object was found for a given
* pointer.
*/
inline virtual void rebind(const TranslationMap & trans)
throw(RebindException);
/**
* Return a vector of all pointers to Interfaced objects used in this
* object.
* @return a vector of pointers.
*/
inline virtual IVector getReferences();
//@}
private:
/**
* Member function which calculate the coupling
*/
//@{
/**
* The two-loop parametrization of \f$\alpha_S\f$.
* @param q The scale
* @param lam \f$\Lambda_{\rm QCD}\f$
* @param nf The number of flavours
*/
double alphaTwoLoop(Energy q, Energy lam, short nf);
/**
* Return the two loop \f$\Lambda\f$ at the scale
* Hacked in masses by hand for the moment before proper
* interfacing... obtained lambda solutions numerically in
* Mathematica with my alphas.m using two-loop alphas from PDT2002
* and as(M_Z=91.2GeV) = 0.118 *** ACHTUNG! *** this HAS to be done
* automatically acc to the masses and as(M_Z) given by the PDT
* class (which is supposed to be up-to-date).
* @param q The scale
* @return The number of flavours at the scale and \f$\Lambda\f$.
*/
pair<short, Energy> getLamNfTwoLoop(Energy q);
/**
* A toy parametrization of \f$\alpha_S\f$ with different parametrizations
* of the IR behaviour, below q2min, set by type.
* Default is type = 1, i.e. alpha_s = 0 below q2min.
* @param q2 The scale
* @param q2min The minimum value below which the coupling is considered to
* be non-pertburative
* @param type The type of behaviour
*/
double alpha_s(double q2, double q2min, int type);
//@}
private:
/**
* The static object used to initialize the description of this class.
* Indicates that this is a concrete class with persistent data.
*/
static ClassDescription<ShowerAlphaQCD> initShowerAlphaQCD;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
ShowerAlphaQCD & operator=(const ShowerAlphaQCD &);
private:
/**
* Minimum value of the scale
*/
Energy _Qmin;
/**
* Parameter controlling the behaviour of \f$\alpha_S\f$ in the non-perturbative
* region.
*/
int _asType;
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the
* base classes of ShowerAlphaQCD. */
template <>
struct BaseClassTrait<Herwig::ShowerAlphaQCD,1> {
/** Typedef of the first base class of ShowerAlphaQCD. */
typedef Herwig::ShowerAlpha NthBase;
};
/** This template specialization informs ThePEG about the name of
* the ShowerAlphaQCD class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::ShowerAlphaQCD>
: public ClassTraitsBase<Herwig::ShowerAlphaQCD> {
/** Return a platform-independent class name */
static string className() { return "Herwig++::ShowerAlphaQCD"; }
/** Return the name(s) of the shared library (or libraries) be loaded to get
* access to the ShowerAlphaQCD class and any other class on which it depends
* (except the base class). */
static string library() { return "HwShower.so"; }
};
/** @endcond */
}
#include "ShowerAlphaQCD.icc"
#ifndef ThePEG_TEMPLATES_IN_CC_FILE
// #include "ShowerAlphaQCD.tcc"
#endif
#endif /* HERWIG_ShowerAlphaQCD_H */

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