Dipole/Utility/PDFRatio.h

0001 // -*- C++ -*-
0002 //
0003 // PDFRatio.h is a part of Herwig - A multi-purpose Monte Carlo event generator
0004 // Copyright (C) 2002-2019 The Herwig Collaboration
0005 //
0006 // Herwig is licenced under version 3 of the GPL, see COPYING for details.
0007 // Please respect the MCnet academic guidelines, see GUIDELINES for details.
0008 //
0009 #ifndef HERWIG_PDFRatio_H
0010 #define HERWIG_PDFRatio_H
0011 //
0012 // This is the declaration of the PDFRatio class.
0013 //
0014
0015 #include "ThePEG/Handlers/HandlerBase.h"
0016 #include "ThePEG/PDF/PDF.h"
0017
0018 namespace Herwig {
0019
0020 using namespace ThePEG;
0021
0022 /**
0023  * \ingroup DipoleShower
0024  * \author Simon Platzer
0025  *
0026  * \brief PDFRatio implements numerically stable PDF ratios.
0027  *
0028  * @see \ref PDFRatioInterfaces "The interfaces"
0029  * defined for PDFRatio.
0030  */
0031 class PDFRatio: public HandlerBase {
0032
0033 public:
0034
0035   /**
0036    * The default constructor.
0037    */
0038   PDFRatio();
0039
0040 public:
0041
0042   /**
0043    * For the given PDF, scale and partons from and to and
0044    * x,z values return the ratio xf_to(x/z) / xf_from(x)
0045    */
0046   double operator() (const PDF& pdf,
0047              Energy2 scale,
0048              tcPDPtr from, tcPDPtr to,
0049              double x, double z) const;
0050
0051 public:
0052
0053   /** @name Functions used by the persistent I/O system. */
0054   //@{
0055   /**
0056    * Function used to write out object persistently.
0057    * @param os the persistent output stream written to.
0058    */
0059   void persistentOutput(PersistentOStream & os) const;
0060
0061   /**
0062    * Function used to read in object persistently.
0063    * @param is the persistent input stream read from.
0064    * @param version the version number of the object when written.
0065    */
0066   void persistentInput(PersistentIStream & is, int version);
0067   //@}
0068
0069   /**
0070    * The standard Init function used to initialize the interfaces.
0071    * Called exactly once for each class by the class description system
0072    * before the main function starts or
0073    * when this class is dynamically loaded.
0074    */
0075   static void Init();
0076
0077 protected:
0078
0079   /** @name Clone Methods. */
0080   //@{
0081   /**
0082    * Make a simple clone of this object.
0083    * @return a pointer to the new object.
0084    */
0085   virtual IBPtr clone() const;
0086
0087   /** Make a clone of this object, possibly modifying the cloned object
0088    * to make it sane.
0089    * @return a pointer to the new object.
0090    */
0091   virtual IBPtr fullclone() const;
0092   //@}
0093
0094
0095 // If needed, insert declarations of virtual function defined in the
0096 // InterfacedBase class here (using ThePEG-interfaced-decl in Emacs).
0097
0098 private:
0099
0100   /**
0101    * The x from which on extrapolation should
0102    * be done for valence partons.
0103    */
0104   double theValenceExtrapolation;
0105
0106   /**
0107    * The x from which on extrapolation should
0108    * be done for sea partons.
0109    */
0110   double theSeaExtrapolation;
0111
0112   /**
0113    * The scale below which the PDF will be frozen
0114    */
0115   Energy theFreezingScale;
0116
0117 private:
0118
0119   /**
0120    * The static object used to initialize the description of this class.
0121    * Indicates that this is a concrete class with persistent data.
0122    */
0123   static ClassDescription<PDFRatio> initPDFRatio;
0124
0125   /**
0126    * The assignment operator is private and must never be called.
0127    * In fact, it should not even be implemented.
0128    */
0129   PDFRatio & operator=(const PDFRatio &) = delete;
0130
0131 };
0132
0133 }
0134
0135 #include "ThePEG/Utilities/ClassTraits.h"
0136
0137 namespace ThePEG {
0138
0139 /** @cond TRAITSPECIALIZATIONS */
0140
0141 /** This template specialization informs ThePEG about the
0142  *  base classes of PDFRatio. */
0143 template <>
0144 struct BaseClassTrait<Herwig::PDFRatio,1> {
0145   /** Typedef of the first base class of PDFRatio. */
0146   typedef HandlerBase NthBase;
0147 };
0148
0149 /** This template specialization informs ThePEG about the name of
0150  *  the PDFRatio class and the shared object where it is defined. */
0151 template <>
0152 struct ClassTraits<Herwig::PDFRatio>
0153   : public ClassTraitsBase<Herwig::PDFRatio> {
0154   /** Return a platform-independent class name */
0155   static string className() { return "Herwig::PDFRatio"; }
0156   /**
0157    * The name of a file containing the dynamic library where the class
0158    * PDFRatio is implemented. It may also include several, space-separated,
0159    * libraries if the class PDFRatio depends on other classes (base classes
0160    * excepted). In this case the listed libraries will be dynamically
0161    * linked in the order they are specified.
0162    */
0163   static string library() { return "HwDipoleShower.so"; }
0164 };
0165
0166 /** @endcond */
0167
0168 }
0169
0170 #endif /* HERWIG_PDFRatio_H */