Matchbox/Matching/QTildeMatching.h

0001 // -*- C++ -*-
0002 //
0003 // QTildeMatching.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_QTildeMatching_H
0010 #define Herwig_QTildeMatching_H
0011 //
0012 // This is the declaration of the QTildeMatching class.
0013 //
0014
0015 #include "Herwig/MatrixElement/Matchbox/Matching/ShowerApproximation.h"
0016 #include "Herwig/Shower/ShowerHandler.h"
0017 #include "Herwig/Shower/QTilde/Base/PartnerFinder.h"
0018 #include "Herwig/Shower/QTilde/SplittingFunctions/SudakovFormFactor.h"
0019
0020 namespace Herwig {
0021
0022 using namespace ThePEG;
0023
0024 /**
0025  * \ingroup Matchbox
0026  * \author Simon Platzer
0027  *
0028  * \brief QTildeMatching implements NLO matching with the default shower.
0029  *
0030  */
0031 class QTildeMatching: public Herwig::ShowerApproximation {
0032
0033 public:
0034
0035   /**
0036    * The default constructor.
0037    */
0038   QTildeMatching();
0039
0040 public:
0041
0042   /**
0043    * Return the shower approximation to the real emission cross
0044    * section for the given pair of Born and real emission
0045    * configurations.
0046    */
0047   virtual CrossSection dSigHatDR() const;
0048
0049   /**
0050    * Return the shower approximation splitting kernel for the given
0051    * pair of Born and real emission configurations in units of the
0052    * Born center of mass energy squared, and including a weight to
0053    * project onto the splitting given by the dipole used.
0054    */
0055   virtual double me2() const;
0056
0057   /**
0058    * Determine if the configuration is below or above the cutoff.
0059    */
0060   virtual void checkCutoff();
0061
0062   /**
0063    * Determine all kinematic variables which are not provided by the
0064    * dipole kinematics; store all shower variables in the respective
0065    * dipole object for later use.
0066    */
0067   virtual void getShowerVariables();
0068
0069 protected:
0070
0071   /**
0072    * Return true, if the shower was able to generate an emission
0073    * leading from the given Born to the given real emission process.
0074    */
0075   virtual bool isInShowerPhasespace() const;
0076
0077   /**
0078    * Return true, if the shower emission leading from the given Born
0079    * to the given real emission process would have been generated
0080    * above the shower's infrared cutoff.
0081    */
0082   virtual bool isAboveCutoff() const;
0083
0084   /**
0085    * Calculate qtilde^2 and z for the splitting considered
0086    */
0087   void calculateShowerVariables() const;
0088
0089   /**
0090    * Return the splitting function as a function of the kinematic
0091    * variables
0092    */
0093   double splitFn(const pair<Energy2,double>&) const;
0094
0095 public:
0096
0097   /** @name Functions used by the persistent I/O system. */
0098   //@{
0099   /**
0100    * Function used to write out object persistently.
0101    * @param os the persistent output stream written to.
0102    */
0103   void persistentOutput(PersistentOStream & os) const;
0104
0105   /**
0106    * Function used to read in object persistently.
0107    * @param is the persistent input stream read from.
0108    * @param version the version number of the object when written.
0109    */
0110   void persistentInput(PersistentIStream & is, int version);
0111   //@}
0112
0113   /**
0114    * The standard Init function used to initialize the interfaces.
0115    * Called exactly once for each class by the class description system
0116    * before the main function starts or
0117    * when this class is dynamically loaded.
0118    */
0119   static void Init();
0120
0121 protected:
0122
0123   /** @name Clone Methods. */
0124   //@{
0125   /**
0126    * Make a simple clone of this object.
0127    * @return a pointer to the new object.
0128    */
0129   virtual IBPtr clone() const;
0130
0131   /** Make a clone of this object, possibly modifying the cloned object
0132    * to make it sane.
0133    * @return a pointer to the new object.
0134    */
0135   virtual IBPtr fullclone() const;
0136   //@}
0137
0138
0139 // If needed, insert declarations of virtual function defined in the
0140 // InterfacedBase class here (using ThePEG-interfaced-decl in Emacs).
0141
0142 protected:
0143
0144   /** @name Standard Interfaced functions. */
0145   //@{
0146   /**
0147    * Initialize this object after the setup phase before saving an
0148    * EventGenerator to disk.
0149    * @throws InitException if object could not be initialized properly.
0150    */
0151   virtual void doinit();
0152
0153   /**
0154    * Initialize this object. Called in the run phase just before
0155    * a run begins.
0156    */
0157   virtual void doinitrun();
0158   //@}
0159
0160 private:
0161
0162   /**
0163    * The assignment operator is private and must never be called.
0164    * In fact, it should not even be implemented.
0165    */
0166   QTildeMatching & operator=(const QTildeMatching &) = delete;
0167
0168   /**
0169    * The shower handler to be used
0170    */
0171   Ptr<ShowerHandler>::ptr theShowerHandler;
0172
0173   /**
0174    * The qtilde partner finder for calculating the hard scales
0175    */
0176   Ptr<PartnerFinder>::ptr theQTildeFinder;
0177
0178   /**
0179    * The qtilde Sudakov to access the cutoff
0180    */
0181   Ptr<SudakovFormFactor>::ptr theQTildeSudakov;
0182
0183   /**
0184    * True, if PDF weight should be corrected for z/x mismatch at the
0185    * hard phase space boundary
0186    */
0187   bool theCorrectForXZMismatch;
0188
0189 };
0190
0191 }
0192
0193 #endif /* Herwig_QTildeMatching_H */