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0001 // -*- C++ -*-
0002 //
0003 // VectorMesonCurrent.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 THEPEG_VectorMesonCurrent_H
0010 #define THEPEG_VectorMesonCurrent_H
0011 // This is the declaration of the VectorMesonCurrent class.
0012 
0013 #include "WeakCurrent.h"
0014 
0015 namespace Herwig {
0016 using namespace ThePEG;
0017 
0018 /** \ingroup Decay
0019  *
0020  *  The weak current for the production of one (pseudo)-vector meson
0021  *
0022  *  In this case the current is given by
0023  *  \f[J^\mu = f_V \epsilon^\mu,\f]
0024  *  where
0025  * - \f$f_V\f$ is the decay constant of the vector meson,
0026  * - \f$\epsilon^\mu\f$ is the polarizaion vector of the outgoing vector meson.
0027  *
0028  * @see WeakCurrent.
0029  * 
0030  */
0031 class VectorMesonCurrent: public WeakCurrent {
0032 
0033 public:
0034 
0035   /**
0036    * Default constructor
0037    */
0038   VectorMesonCurrent();
0039 
0040 public:
0041 
0042   /** @name Functions used by the persistent I/O system. */
0043   //@{
0044   /**
0045    * Function used to write out object persistently.
0046    * @param os the persistent output stream written to.
0047    */
0048   void persistentOutput(PersistentOStream & os) const;
0049 
0050   /**
0051    * Function used to read in object persistently.
0052    * @param is the persistent input stream read from.
0053    * @param version the version number of the object when written.
0054    */
0055   void persistentInput(PersistentIStream & is, int version);
0056   //@}
0057 
0058   /**
0059    * Standard Init function used to initialize the interfaces.
0060    */
0061   static void Init();
0062 
0063 public:
0064 
0065   /** @name Methods for the construction of the phase space integrator. */
0066   //@{
0067   /**
0068    * Complete the construction of the decay mode for integration.classes inheriting
0069    * from this one.
0070    * This method is purely virtual and must be implemented in the classes inheriting
0071    * from WeakCurrent.
0072    * @param icharge   The total charge of the outgoing particles in the current.
0073    * @param resonance If specified only include terms with this particle
0074    * @param flavour Information on the required flavours of the quarks
0075    * @param imode     The mode in the current being asked for.
0076    * @param mode      The phase space mode for the integration
0077    * @param iloc      The location of the of the first particle from the current in
0078    *                  the list of outgoing particles.
0079    * @param ires      The location of the first intermediate for the current.
0080    * @param phase     The prototype phase space channel for the integration.
0081    * @param upp       The maximum possible mass the particles in the current are
0082    *                  allowed to have.
0083    * @return Whether the current was sucessfully constructed.
0084    */
0085   virtual bool createMode(int icharge, tcPDPtr resonance,
0086               FlavourInfo flavour,
0087               unsigned int imode,PhaseSpaceModePtr mode,
0088               unsigned int iloc,int ires,
0089               PhaseSpaceChannel phase, Energy upp );
0090 
0091   /**
0092    * The particles produced by the current. This just returns the pseudoscalar
0093    * meson.
0094    * @param icharge The total charge of the particles in the current.
0095    * @param imode The mode for which the particles are being requested
0096    * @param iq The PDG code for the quark
0097    * @param ia The PDG code for the antiquark
0098    * @return The external particles for the current.
0099    */
0100   virtual tPDVector particles(int icharge, unsigned int imode, int iq, int ia);
0101   //@}
0102 
0103   /**
0104    * Hadronic current. This method is purely virtual and must be implemented in
0105    * all classes inheriting from this one.
0106    * @param resonance If specified only include terms with this particle
0107    * @param flavour Information on the required flavours of the quarks
0108    * @param imode The mode
0109    * @param ichan The phase-space channel the current is needed for.
0110    * @param scale The invariant mass of the particles in the current.
0111    * @param outgoing The particles produced in the decay
0112    * @param momenta  The momenta of the particles produced in the decay
0113    * @param meopt Option for the calculation of the matrix element
0114    * @return The current. 
0115    */
0116   virtual vector<LorentzPolarizationVectorE> 
0117   current(tcPDPtr resonance,
0118       FlavourInfo flavour,
0119       const int imode, const int ichan,Energy & scale,
0120       const tPDVector & outgoing,
0121       const vector<Lorentz5Momentum> & momenta,
0122       DecayIntegrator::MEOption meopt) const;
0123 
0124   /**
0125    *   Construct the SpinInfo for the decay products
0126    */
0127   virtual void constructSpinInfo(ParticleVector decay) const;
0128 
0129   /**
0130    * Accept the decay. Checks the meson against the list
0131    * @param id The id's of the particles in the current.
0132    * @return Can this current have the external particles specified.
0133    */
0134   virtual bool accept(vector<int> id);
0135 
0136   /**
0137    * Return the decay mode number for a given set of particles in the current. 
0138    * Checks the meson against the list
0139    * @param id The id's of the particles in the current.
0140    * @return The number of the mode
0141    */
0142   virtual unsigned int decayMode(vector<int> id);
0143 
0144   /**
0145    * Output the setup information for the particle database
0146    * @param os The stream to output the information to
0147    * @param header Whether or not to output the information for MySQL
0148    * @param create Whether or not to add a statement creating the object
0149    */
0150   virtual void dataBaseOutput(ofstream & os,bool header,bool create) const;
0151 
0152 protected:
0153 
0154   /** @name Clone Methods. */
0155   //@{
0156   /**
0157    * Make a simple clone of this object.
0158    * @return a pointer to the new object.
0159    */
0160   virtual IBPtr clone() const {return new_ptr(*this);}
0161 
0162   /** Make a clone of this object, possibly modifying the cloned object
0163    * to make it sane.
0164    * @return a pointer to the new object.
0165    */
0166   virtual IBPtr fullclone() const {return new_ptr(*this);}
0167   //@}
0168   
0169 protected:
0170 
0171   /** @name Standard Interfaced functions. */
0172   //@{
0173   /**
0174    * Initialize this object after the setup phase before saving and
0175    * EventGenerator to disk.
0176    * @throws InitException if object could not be initialized properly.
0177    */
0178   virtual void doinit();
0179   //@}
0180 
0181 private:
0182 
0183   /**
0184    * Private and non-existent assignment operator.
0185    */
0186   VectorMesonCurrent & operator=(const VectorMesonCurrent &) = delete;
0187 
0188 private:
0189 
0190   /**
0191    * The PDG code for the meson.
0192    */
0193   vector<int> _id;
0194 
0195   /**
0196    * The decay constant
0197    */
0198   vector<Energy2> _decay_constant;
0199 
0200   /**
0201    * initial size of the vectors
0202    */
0203   unsigned int _initsize;
0204 };
0205 
0206 }
0207 
0208 
0209 #endif /* THEPEG_VectorMesonCurrent_H */