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 // -*- C++ -*-
 //
 // OneKaonTwoPionCurrent.h is a part of Herwig - A multi-purpose Monte Carlo event generator
 // Copyright (C) 2002-2019 The Herwig Collaboration
 //
 // Herwig is licenced under version 3 of the GPL, see COPYING for details.
 // Please respect the MCnet academic guidelines, see GUIDELINES for details.
 //
 #ifndef HERWIG_OneKaonTwoPionCurrent_H
 #define HERWIG_OneKaonTwoPionCurrent_H
 //
 // This is the declaration of the OneKaonTwoPionCurrent class.
 //
 
 #include "WeakCurrent.h"
 #include "Herwig/Decay/ResonanceHelpers.h"
 #include <numeric>
 
 namespace Herwig {
 
 using namespace ThePEG;
 
 /**
  * The OneKaonTwoPionCurrent class implements the model of M. Finkemeier 
  * and E.~Mirkes, Z. Phys. C 69 (1996) 243 [arXiv:hep-ph/9503474],
  * for the weak current for three mesons where at least one of the mesons is
  * a kaon.
  *
  * \ingroup Decay
  *
  *  This is the base class for the three meson decays of the weak current.
  *  It is designed so that the currents for the following modes can be implemented
  *  in classes inheriting from this
  * - \f$    \pi^-  \pi^-    \pi^+ \f$, (imode=0)
  * - \f$    \pi^0  \pi^0    \pi^- \f$, (imode=1)
  * - \f$    K^-   \pi^-    K^+ \f$, (imode=2)
  * - \f$    K^0   \pi^-    \bar{K}^0\f$, (imode=3)
  * - \f$    K^-   \pi^0    K^0 \f$, (imode=4)
  * - \f$    \pi^0  \pi^0    K^- \f$, (imode=5)
  * - \f$    K^-   \pi^-    \pi^+ \f$, (imode=6)
  * - \f$    \pi^-  \bar{K}^0  \pi^0 \f$, (imode=7)
  * - \f$    \pi^-  \pi^0    \eta \f$, (imode=8)
  *
  * obviously there are other modes with three pseudoscalar mesons for the decay
  * of the weak current but this model original came from \f$\tau\f$ decay where
  * these are the only modes. However one case which is important is the inclusion
  * of the mixing in the neutral kaon sector for which we include the additional
  * currents
  * - \f$    K^0_S \pi^- K^0_S\f$, (imode=9)
  * - \f$    K^0_L \pi^- K^0_L\f$, (imode=10)
  * - \f$    K^0_S \pi^- K^0_L\f$, (imode=11)
  *
  *  In this case the current is given by
  *  \f[ J^\mu = \left(g^{\mu\nu}-\frac{q^\mu q^\nu}{q^2}\right)
  *   \left[F_1(p_2-p_3)^\mu +F_2(p_3-p_1)^\mu+F_3(p_1-p_2)^\mu\right]
  *  +q^\mu F_4
  *  +F_5\epsilon^{\mu\alpha\beta\gamma}p_1^\alpha p_2^\beta p_3^\gamma
  *  \f]
  * where
  * - \f$p_{1,2,3}\f$ are the momenta of the mesons in the order given above.
  * - \f$F_1,F_2,F_3,F_4,F_5\f$ are the form factors which must be 
  *  calculated in the calculateFormFactors member which should be implemented
  * in classes inheriting from this.
  *
  * @see WeakCurrent.
  *  
  * \author Peter Richardson
  * @see \ref OneKaonTwoPionCurrentInterfaces "The interfaces"
  * defined for OneKaonTwoPionCurrent.
  */
 class OneKaonTwoPionCurrent: public WeakCurrent {
 
 public:
 
   /**
    * The default constructor.
    */
   OneKaonTwoPionCurrent();
 
   /** @name Methods for the construction of the phase space integrator. */
   //@{
   /**
    * Complete the construction of the decay mode for integration.classes inheriting
    * from this one.
    * This method is purely virtual and must be implemented in the classes inheriting
    * from WeakCurrent.
    * @param icharge   The total charge of the outgoing particles in the current.
    * @param resonance If specified only include terms with this particle
    * @param flavour Information on the required flavours of the quarks
    * @param imode     The mode in the current being asked for.
    * @param mode      The phase space mode for the integration
    * @param iloc      The location of the of the first particle from the current in
    *                  the list of outgoing particles.
    * @param ires      The location of the first intermediate for the current.
    * @param phase     The prototype phase space channel for the integration.
    * @param upp       The maximum possible mass the particles in the current are
    *                  allowed to have.
    * @return Whether the current was sucessfully constructed.
    */
   virtual bool createMode(int icharge, tcPDPtr resonance,
               FlavourInfo flavour,
               unsigned int imode,PhaseSpaceModePtr mode,
               unsigned int iloc,int ires,
               PhaseSpaceChannel phase, Energy upp );
   //@}
 
 
   /**
    * Hadronic current. This method is purely virtual and must be implemented in
    * all classes inheriting from this one.
    * @param resonance If specified only include terms with this particle
    * @param flavour Information on the required flavours of the quarks
    * @param imode The mode
    * @param ichan The phase-space channel the current is needed for.
    * @param scale The invariant mass of the particles in the current.
    * @param outgoing The particles produced in the decay
    * @param momenta  The momenta of the particles produced in the decay
    * @param meopt Option for the calculation of the matrix element
    * @return The current. 
    */
   virtual vector<LorentzPolarizationVectorE> 
   current(tcPDPtr resonance,
       FlavourInfo flavour,
       const int imode, const int ichan,Energy & scale,
       const tPDVector & outgoing,
       const vector<Lorentz5Momentum> & momenta,
       DecayIntegrator::MEOption meopt) const;
 
   /**
    * Accept the decay. Checks the mesons against the list.
    * @param id The id's of the particles in the current.
    * @return Can this current have the external particles specified.
    */
   virtual bool accept(vector<int> id);
 
   /**
    * Return the decay mode number for a given set of particles in the current. 
    * Checks the mesons against the list.
    * @param id The id's of the particles in the current.
    * @return The number of the mode
    */
   virtual unsigned int decayMode(vector<int> id);
 
   /**
    * The particles produced by the current. This returns the mesons for the mode.
    * @param icharge The total charge of the particles in the current.
    * @param imode The mode for which the particles are being requested
    * @param iq The PDG code for the quark
    * @param ia The PDG code for the antiquark
    * @return The external particles for the current.
    */
   virtual tPDVector particles(int icharge, unsigned int imode, int iq, int ia);
   
   /**
    * Output the setup information for the particle database
    * @param os The stream to output the information to
    * @param header Whether or not to output the information for MySQL
    * @param create Whether or not to add a statement creating the object
    */
   virtual void dataBaseOutput(ofstream & os,bool header,bool create) const;
 
 public:
 
   /** @name Functions used by the persistent I/O system. */
   //@{
   /**
    * Function used to write out object persistently.
    * @param os the persistent output stream written to.
    */
   void persistentOutput(PersistentOStream & os) const;
 
   /**
    * Function used to read in object persistently.
    * @param is the persistent input stream read from.
    * @param version the version number of the object when written.
    */
   void persistentInput(PersistentIStream & is, int version);
   //@}
 
   /**
    * The standard Init function used to initialize the interfaces.
    * Called exactly once for each class by the class description system
    * before the main function starts or
    * when this class is dynamically loaded.
    */
   static void Init();
 
 protected:
 
   /** @name Clone Methods. */
   //@{
   /**
    * Make a simple clone of this object.
    * @return a pointer to the new object.
    */
   virtual IBPtr clone() const;
 
   /** Make a clone of this object, possibly modifying the cloned object
    * to make it sane.
    * @return a pointer to the new object.
    */
   virtual IBPtr fullclone() const;
   //@}
 
 protected:
 
   /**
    * Initialize this object after the setup phase before saving and
    * EventGenerator to disk.
    * @throws InitException if object could not be initialized properly.
    */
   virtual void doinit();
 
 private:
 
   /**
    * The assignment operator is private and must never be called.
    * In fact, it should not even be implemented.
    */
   OneKaonTwoPionCurrent & operator=(const OneKaonTwoPionCurrent &) = delete;
 
 private:
 
   /**
    *  The \f$\rho\f$ lineshape for the axial-vector terms
    * @param q2 The scale \f$q^2\f$ for the lineshape
    * @param ires Which \f$\rho\f$ multiplet
    */
   Complex Trho1(Energy2 q2,int ires) const {
     if(ires>=int(_rho1wgts.size())) return 0.;
     double norm = std::accumulate(_rho1wgts.begin(),_rho1wgts.end(),0.);
     unsigned int imin=0,imax=_rho1wgts.size();
     if(ires>0) {
       imin=ires;
       imax=imin+1;
     }
     Complex output(0.);
     for(unsigned int ix=imin;ix<imax;++ix)
       output+=_rho1wgts[ix]*
     Resonance::BreitWignerPWave(q2,_rho1mass[ix],_rho1width[ix],_mpi,_mpi);
     return output/norm;
   }
 
   /**
    *  The \f$K^*\f$ lineshape for the axial-vector terms
    * @param q2 The scale \f$q^2\f$ for the lineshape
    * @param ires Which \f$K^*\f$ multiplet
    */
   Complex TKstar1(Energy2 q2,int ires) const {
     if(ires>=int(_kstar1wgts.size())) return 0.;
     double norm = std::accumulate(_kstar1wgts.begin(),_kstar1wgts.end(),0.);
     unsigned int imin=0,imax=_kstar1wgts.size();
     if(ires>0) {
       imin=ires;
       imax=imin+1;
     }
     Complex output(0.);
     for(unsigned int ix=imin;ix<imax;++ix)
       output+=_kstar1wgts[ix]*
     Resonance::BreitWignerPWave(q2,_kstar1mass[ix],_kstar1width[ix],_mK,_mpi);
     return output/norm;
   }
 
   /**
    *  The \f$K^*\f$ lineshape for the vector terms
    * @param q2 The scale \f$q^2\f$ for the lineshape
    * @param ires Which \f$K^*\f$ multiplet
    */
   Complex TKstar2(Energy2 q2,int ires) const {
     if(ires>=int(_kstar2wgts.size())) return 0.;
     double norm = std::accumulate(_kstar2wgts.begin(),_kstar2wgts.end(),0.);
     unsigned int imin=0,imax=_kstar2wgts.size();
     if(ires>0) {
       imin=ires;
       imax=imin+1;
     }
     Complex output(0.);
     for(unsigned int ix=imin;ix<imax;++ix)
       output+=_kstar2wgts[ix]*
     Resonance::BreitWignerPWave(q2,_kstar2mass[ix],_kstar2width[ix],_mK,_mpi);
     return output/norm;
   }
 
   /**
    *  The \f$K_1\f$ line shape
    * @param q2 The scale \f$q^2\f$ for the Breit-Wigner
    * @param iopt Whether this is \f$K^*\pi\f$ or \f$\rho K\f$.
    * @param ires the resonance
    */
   Complex TK1(Energy2 q2,unsigned int iopt,int ires) const;
 
 private:
 
   /**
    *  Parameters for the \f$\rho\f$ in the axial-vector terms
    */
   //@{
   /**
    *  Weight for the different resonances
    */
   vector<double> _rho1wgts;
 
   /**
    *  Masses
    */
   vector<Energy> _rho1mass;
 
   /**
    *  Widths
    */
   vector<Energy> _rho1width;
   //@}
 
   /**
    *  Parameters for the \f$K^*\f$ in the axial-vector terms
    */
   //@{
   /**
    *  Weight for the different resonances
    */
   vector<double> _kstar1wgts;
 
   /**
    *  Masses
    */
   vector<Energy> _kstar1mass;
 
   /**
    *  Widths
    */
   vector<Energy> _kstar1width;
   //@}
 
   /**
    *  Parameters for the \f$K^*\f$ in the vector terms
    */
   //@{
   /**
    *  Weight for the different resonances
    */
   vector<double> _kstar2wgts;
 
   /**
    *  Masses
    */
   vector<Energy> _kstar2mass;
 
   /**
    *  Widths
    */
   vector<Energy> _kstar2width;
   //@}
 
   /**
    *  Parameters for the three meson resonances
    */
   //@{
 
   /**
    *  The masses of the \f$aK1\f$ resonances.
    */
   vector<Energy> _k1mass;
 
   /**
    *  The widths of the \f$K_1\f$ resonances.
    */
   vector<Energy> _k1width;
 
   /**
    *  The weights for the different \f$K_1\f$ resonances for \f$K_1\to K^*\pi\f$
    */
   vector<double> _k1wgta;
 
   /**
    *  The weights for the different \f$K_1\f$ resonaces for \f$K_1\to\rho K\f$.
    */
   vector<double> _k1wgtb;
   //@}
 
   /**
    * The pion decay constant, \f$f_\pi\f$.
    */
   Energy _fpi;
 
   /**
    * The pion mass
    */
   Energy _mpi;
 
   /**
    * The kaon mass
    */
   Energy _mK;
   //@}
 };
 
 }
 
 #endif /* HERWIG_OneKaonTwoPionCurrent_H */

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