Herwig/PDF/MPIPDF.h

0001 // -*- C++ -*-
0002 //
0003 // MPIPDF.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_MPIPDF_H
0010 #define HERWIG_MPIPDF_H
0011 //
0012 // This is the declaration of the MPIPDF class.
0013 //
0014
0015 #include "ThePEG/PDF/PDFBase.h"
0016 #include "MPIPDF.fh"
0017
0018 namespace Herwig {
0019 using namespace ThePEG;
0020 /**
0021  * The MPIPDF class defines
0022  * a modified pdf which uses an existing pdf object to add
0023  * modifications like removing the valence part of it, which
0024  * is needed in the backward evolution of secondary scatters.
0025  *
0026  * \author Manuel B\"ahr
0027  *
0028  * @see \ref MPIPDFInterfaces "The interfaces"
0029  * defined for MPIPDF.
0030  */
0031 class MPIPDF: public PDFBase {
0032
0033 public:
0034
0035   /**
0036    * The constructor which takes a PDF object as argument, to work with.
0037    */
0038   MPIPDF(cPDFPtr orig = cPDFPtr()) : thePDF(orig) {}
0039
0040 public:
0041
0042   /** @name Virtual functions to be overridden by sub-classes. */
0043   //@{
0044   /**
0045    * Return true if this PDF can handle the extraction of partons from
0046    * the given \a particle.
0047    */
0048   virtual bool canHandleParticle(tcPDPtr particle) const;
0049
0050   /**
0051    * Return the partons which this PDF may extract from the given
0052    * \a particle.
0053    */
0054   virtual cPDVector partons(tcPDPtr particle) const;
0055
0056   /**
0057    * The density. Return the pdf for the given \a parton inside the
0058    * given \a particle for the virtuality \a partonScale and momentum
0059    * fraction \a x. The \a particle is assumed to have a virtuality \a
0060    * particleScale. For MPIPDF, only the sea quark densities
0061    * are included here!
0062    */
0063   virtual double xfx(tcPDPtr particle, tcPDPtr parton, Energy2 partonScale,
0064              double x, double eps = 0.0,
0065              Energy2 particleScale = ZERO) const;
0066
0067
0068   /**
0069    * The valence density. Return the pdf for the given cvalence \a
0070    * parton inside the given \a particle for the virtuality \a
0071    * partonScale and momentum fraction \a x. The \a particle is
0072    * assumed to have a virtuality \a particleScale. If not overidden
0073    * by a sub class this implementation will assume that the
0074    * difference between a quark and anti-quark distribution is due do
0075    * valense quarks, but return zero for anything else.
0076    */
0077   virtual double xfvx(tcPDPtr particle, tcPDPtr parton, Energy2 partonScale,
0078               double x, double eps = 0.0,
0079               Energy2 particleScale = ZERO) const;
0080   //@}
0081
0082
0083 public:
0084
0085   /** @name Functions used by the persistent I/O system. */
0086   //@{
0087   /**
0088    * Function used to write out object persistently.
0089    * @param os the persistent output stream written to.
0090    */
0091   void persistentOutput(PersistentOStream & os) const;
0092
0093   /**
0094    * Function used to read in object persistently.
0095    * @param is the persistent input stream read from.
0096    * @param version the version number of the object when written.
0097    */
0098   void persistentInput(PersistentIStream & is, int version);
0099   //@}
0100
0101   /**
0102    * The standard Init function used to initialize the interfaces.
0103    * Called exactly once for each class by the class description system
0104    * before the main function starts or
0105    * when this class is dynamically loaded.
0106    */
0107   static void Init();
0108
0109 protected:
0110
0111   /** @name Clone Methods. */
0112   //@{
0113   /**
0114    * Make a simple clone of this object.
0115    * @return a pointer to the new object.
0116    */
0117   virtual IBPtr clone() const;
0118
0119   /** Make a clone of this object, possibly modifying the cloned object
0120    * to make it sane.
0121    * @return a pointer to the new object.
0122    */
0123   virtual IBPtr fullclone() const;
0124   //@}
0125
0126
0127 // If needed, insert declarations of virtual function defined in the
0128 // InterfacedBase class here (using ThePEG-interfaced-decl in Emacs).
0129
0130
0131 private:
0132
0133   /**
0134    * The assignment operator is private and must never be called.
0135    * In fact, it should not even be implemented.
0136    */
0137   MPIPDF & operator=(const MPIPDF &) = delete;
0138
0139   /**
0140    * pointer to the underlying ThePEG::PDFBase object, we are modifying.
0141    */
0142   cPDFPtr thePDF;
0143 };
0144
0145 }
0146
0147 #endif /* HERWIG_MPIPDF_H */