Decay/WeakCurrents/PionPhotonCurrent.h

0001 // -*- C++ -*-
0002 #ifndef Herwig_PionPhotonCurrent_H
0003 #define Herwig_PionPhotonCurrent_H
0004 //
0005 // This is the declaration of the PionPhotonCurrent class.
0006 //
0007
0008 #include "WeakCurrent.h"
0009
0010 namespace Herwig {
0011
0012 using namespace ThePEG;
0013
0014 /**
0015  * The PionPhotonCurrent class implements the decay current
0016  * for \f$\pi^{\pm,0} \gamma\f$ via
0017  * intermediate \f$\rho,\omega,\phi,\omega^\prime\f$.
0018  *  It inherits from the <code>WeakCurrent</code>
0019  *  class and implements the hadronic current.
0020  *
0021  *  The model is based on the one from Phys.Rev. D93 (2016) no.9, 092001.
0022  *
0023  * @see \ref PionPhotonCurrentInterfaces "The interfaces"
0024  * defined for PionPhotonCurrent.
0025  */
0026 class PionPhotonCurrent: public WeakCurrent {
0027
0028 public:
0029
0030   /**
0031    * The default constructor.
0032    */
0033   PionPhotonCurrent();
0034
0035 public:
0036
0037   /** @name Methods for the construction of the phase space integrator. */
0038   //@{
0039   /**
0040    * Complete the construction of the decay mode for integration.classes inheriting
0041    * from this one.
0042    * This method is purely virtual and must be implemented in the classes inheriting
0043    * from WeakCurrent.
0044    * @param icharge   The total charge of the outgoing particles in the current.
0045    * @param resonance If specified only include terms with this particle
0046    * @param flavour Information on the required flavours of the quarks
0047    * @param imode     The mode in the current being asked for.
0048    * @param mode      The phase space mode for the integration
0049    * @param iloc      The location of the of the first particle from the current in
0050    *                  the list of outgoing particles.
0051    * @param ires      The location of the first intermediate for the current.
0052    * @param phase     The prototype phase space channel for the integration.
0053    * @param upp       The maximum possible mass the particles in the current are
0054    *                  allowed to have.
0055    * @return Whether the current was sucessfully constructed.
0056    */
0057   virtual bool createMode(int icharge, tcPDPtr resonance,
0058               FlavourInfo flavour,
0059               unsigned int imode,PhaseSpaceModePtr mode,
0060               unsigned int iloc,int ires,
0061               PhaseSpaceChannel phase, Energy upp );
0062
0063   /**
0064    * The particles produced by the current. This just returns the pseudoscalar
0065    * meson.
0066    * @param icharge The total charge of the particles in the current.
0067    * @param imode The mode for which the particles are being requested
0068    * @param iq The PDG code for the quark
0069    * @param ia The PDG code for the antiquark
0070    * @return The external particles for the current.
0071    */
0072   virtual tPDVector particles(int icharge, unsigned int imode, int iq, int ia);
0073   //@}
0074
0075   /**
0076    * Hadronic current. This method is purely virtual and must be implemented in
0077    * all classes inheriting from this one.
0078    * @param resonance If specified only include terms with this particle
0079    * @param flavour Information on the required flavours of the quarks
0080    * @param imode The mode
0081    * @param ichan The phase-space channel the current is needed for.
0082    * @param scale The invariant mass of the particles in the current.
0083    * @param outgoing The particles produced in the decay
0084    * @param momenta  The momenta of the particles produced in the decay
0085    * @param meopt Option for the calculation of the matrix element
0086    * @return The current.
0087    */
0088   virtual vector<LorentzPolarizationVectorE>
0089   current(tcPDPtr resonance,
0090       FlavourInfo flavour,
0091       const int imode, const int ichan,Energy & scale,
0092       const tPDVector & outgoing,
0093       const vector<Lorentz5Momentum> & momenta,
0094       DecayIntegrator::MEOption meopt) const;
0095
0096   /**
0097    *   Construct the SpinInfo for the decay products
0098    */
0099   virtual void constructSpinInfo(ParticleVector decay) const;
0100
0101   /**
0102    * Accept the decay. Checks the meson against the list
0103    * @param id The id's of the particles in the current.
0104    * @return Can this current have the external particles specified.
0105    */
0106   virtual bool accept(vector<int> id);
0107
0108   /**
0109    * Return the decay mode number for a given set of particles in the current.
0110    * Checks the meson against the list
0111    * @param id The id's of the particles in the current.
0112    * @return The number of the mode
0113    */
0114   virtual unsigned int decayMode(vector<int> id);
0115
0116   /**
0117    * Output the setup information for the particle database
0118    * @param os The stream to output the information to
0119    * @param header Whether or not to output the information for MySQL
0120    * @param create Whether or not to add a statement creating the object
0121    */
0122   virtual void dataBaseOutput(ofstream & os,bool header,bool create) const;
0123
0124 public:
0125
0126   /** @name Functions used by the persistent I/O system. */
0127   //@{
0128   /**
0129    * Function used to write out object persistently.
0130    * @param os the persistent output stream written to.
0131    */
0132   void persistentOutput(PersistentOStream & os) const;
0133
0134   /**
0135    * Function used to read in object persistently.
0136    * @param is the persistent input stream read from.
0137    * @param version the version number of the object when written.
0138    */
0139   void persistentInput(PersistentIStream & is, int version);
0140   //@}
0141
0142   /**
0143    * The standard Init function used to initialize the interfaces.
0144    * Called exactly once for each class by the class description system
0145    * before the main function starts or
0146    * when this class is dynamically loaded.
0147    */
0148   static void Init();
0149
0150 protected:
0151
0152   /** @name Clone Methods. */
0153   //@{
0154   /**
0155    * Make a simple clone of this object.
0156    * @return a pointer to the new object.
0157    */
0158   virtual IBPtr clone() const;
0159
0160   /** Make a clone of this object, possibly modifying the cloned object
0161    * to make it sane.
0162    * @return a pointer to the new object.
0163    */
0164   virtual IBPtr fullclone() const;
0165   //@}
0166
0167 protected:
0168
0169   /** @name Standard Interfaced functions. */
0170   //@{
0171   /**
0172    * Initialize this object after the setup phase before saving an
0173    * EventGenerator to disk.
0174    * @throws InitException if object could not be initialized properly.
0175    */
0176   virtual void doinit();
0177   //@}
0178
0179 private:
0180
0181   /**
0182    * The assignment operator is private and must never be called.
0183    * In fact, it should not even be implemented.
0184    */
0185   PionPhotonCurrent & operator=(const PionPhotonCurrent &) = delete;
0186
0187 private:
0188
0189   /**
0190    *   Mass for the resonances
0191    */
0192   vector<Energy> resMasses_;
0193
0194   /**
0195    *  Widths for the resonances
0196    */
0197   vector<Energy> resWidths_;
0198
0199   /**
0200    *  Amplitudes for couplings for the resonances
0201    */
0202   vector<InvEnergy> amp_;
0203
0204   /**
0205    *  Amplitudes for couplings for the resonances
0206    */
0207   vector<double> phase_;
0208
0209   /**
0210    *  Couplings for the resonances
0211    */
0212   vector<complex<InvEnergy> > couplings_;
0213
0214   /**
0215    *  The pion mass
0216    */
0217   Energy mpi_;
0218 };
0219
0220 }
0221
0222 #endif /* Herwig_PionPhotonCurrent_H */