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 // -*- C++ -*-
 //
 // FourPionNovosibirskCurrent.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_FourPionNovosibirskCurrent_H
 #define HERWIG_FourPionNovosibirskCurrent_H
 //
 // This is the declaration of the FourPionNovosibirskCurrent class.
 //
 #include "WeakCurrent.h"
 #include "Herwig/Utilities/Interpolator.h"
 #include "Herwig/Utilities/Kinematics.h"
 
 namespace Herwig {
 using namespace ThePEG;
 
 /** \ingroup Decay
  *
  * The <code>FourPionNovosibirskCurrent</code> class implements the decay of the weak 
  * current to 4 pions using the hadronic currents of
  * Comput. Phys. Commun. 146: 139-153, 2002,
  * which is a model based on the \f$e^+e^-\to4\pi\f$ data from Novosibirsk.
  *
  * It should be noted that there were a large number of mistakes in this paper which 
  * were corrected in hep-ph/0312240.
  *
  * @see WeakCurrent
  * @see FourPionDefaultMatrixElement
  * 
  * \author Peter Richardson
  * 
  */
 class FourPionNovosibirskCurrent: public WeakCurrent {
 
   /**
    * The FourPionDefaultMatrixElement class is a friend so it can perform the
    * integration.
    */
   friend class FourPionDefaultMatrixElement;
 
 public:
 
   /**
    * Default constructor
    */
   FourPionNovosibirskCurrent();
 
   /** @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);
   //@}
 
   /**
    * Standard Init function used to initialize the interfaces.
    */
   static void Init();
 
 public:
 
   /** @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 );
 
   /**
    * The particles produced by the current. This returns the four pions for the
    * current.
    * @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);
   //@}
 
 
   /**
    * 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 this is one of the four pion modes.
    * @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. 
    * Works out which four pion mode this is.
    * @param id The id's of the particles in the current.
    * @return The number of the mode
    */
   virtual unsigned int decayMode(vector<int> id);
 
   /**
    * 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;
 
   /**
    * The matrix element to evaluate the \f$a_1\f$ running width.
    * @param iopt The mode
    * @param q2 The mass of the decaying off-shell \f$a_1\f$, \f$q^2\f$.
    * @param s3 The invariant mass squared of particles 1 and 2, \f$s_3=m^2_{12}\f$.
    * @param s2 The invariant mass squared of particles 1 and 3, \f$s_2=m^2_{13}\f$.
    * @param s1 The invariant mass squared of particles 2 and 3, \f$s_1=m^2_{23}\f$.
    * @param m1 The mass of the first  outgoing particle.
    * @param m2 The mass of the second outgoing particle.
    * @param m3 The mass of the third  outgoing particle.
    * @return The matrix element squared summed over spins.
    */
   double threeBodyMatrixElement(const int iopt, const Energy2 q2,
                 const Energy2 s3, const Energy2 s2, 
                 const Energy2 s1, const Energy  m1,
                 const Energy  m2, const Energy  m3) const;
   
 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:
 
   /** @name Standard Interfaced functions. */
   //@{
   /**
    * 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();
 
   /**
    * Initialize this object to the begining of the run phase.
    */
   virtual void doinitrun();
 
   /**
    * Check sanity of the object during the setup phase.
    */
   virtual void doupdate();
   //@}
 
 private:
 
   /**
    * Private and non-existent assignment operator.
    */
   FourPionNovosibirskCurrent & operator=(const FourPionNovosibirskCurrent &) = delete;
       
 protected:
   
 
   /**
    * Initialize the \f$a_1\f$ width.
    * @param iopt Initialization option
    *  (-1 is full initialization and 0 sets up the interpolator for the running width)
    */
   void inita1width(int iopt);
   
   /**
    * Form foactor for the \f$a_1\f$ vertex.
    * @param q2 The scale \f$q^2\f$.
    * @return The \f$a_1\f$ form factor.
    */
   double a1FormFactor(Energy2 q2) const {
     return sqr((1.+_a1massolam2)/(1.+q2*_onedlam2));   
   }
 
   /**
    * Breit-Wigner for the \f$\sigma\f$ meson
    * @param q2 The scale \f$q^2\f$.
    * @param iopt The pion masses to used (0=\f$\pi^0\f$, 1=\f$\pi^+\f$)
    * @return The Breit-Wigner for the \f$\sigma\f$ meson
    */
   Complex sigmaBreitWigner(Energy2 q2,unsigned int iopt) const;
 
   /**
    * The \f$a_1\f$ breit wigner.
    * @param q2 The scale \f$q^2\f$.
    * @return The Breit-Wigner for the \f$a_1\f$.
    */
   Complex a1BreitWigner(Energy2 q2) const;
 
   /**
    * The Breit-Wigner for the \f$\omega\f$.
    * @param q2 The scale \f$q^2\f$.
    * @return The Breit-Wigner for the \f$\omega\f$.
    */
   Complex omegaBreitWigner(Energy2 q2) const;
 
   /**
    * The Breit-Wigner for the \f$\rho\f$.
    * @param q2 The scale \f$q^2\f$.
    * @return The Breit-Wigner for the \f$\rho\f$.
    */
   Complex rhoBreitWigner(Energy2 q2) const;
 
   /**
    * Return the \f$a_1\f$ running width.
    * @param q2 The scale \f$q^2\f$.
    * @return The running width.
    */
   Energy a1width(Energy2 q2) const {return (*_a1runinter)(q2);}
 
   /**
    * The \f$t_1\f$ current used in calculating the current.
    * @param q1 The first momentum.
    * @param q2 The first momentum.
    * @param q3 The first momentum.
    * @param q4 The first momentum.
    * @return The current \f$t_1\f$.
    */
   LorentzVector<complex<Energy5> > 
   t1(Lorentz5Momentum & q1,Lorentz5Momentum & q2,
      Lorentz5Momentum & q3,Lorentz5Momentum & q4) const;
 
   /**
    * The \f$t_2\f$ current used in calculating the current.
    * @param q1 The first momentum.
    * @param q2 The first momentum.
    * @param q3 The first momentum.
    * @param q4 The first momentum.
    * @param iopt 0 for \f$\sigma\to\pi^+\pi^-\f$ and 1 for \f$\sigma\to\pi^0\pi^0\f$
    * @return The current \f$t_2\f$.
    */
   LorentzVector<complex<Energy5> > 
   t2(Lorentz5Momentum & q1,Lorentz5Momentum & q2,
      Lorentz5Momentum & q3,Lorentz5Momentum & q4,
      unsigned int iopt) const;
 
   /**
    * The \f$t_3\f$ current used in calculating the current.
    * @param q1 The first momentum.
    * @param q2 The first momentum.
    * @param q3 The first momentum.
    * @param q4 The first momentum.
    * @return The current \f$t_3\f$.
    */
   LorentzVector<complex<Energy5> > 
   t3(Lorentz5Momentum & q1,Lorentz5Momentum & q2,
      Lorentz5Momentum & q3,Lorentz5Momentum & q4) const;
 
   /**
    * The G functions of hep-ph/0201149
    * @param q2 The scale \f$q^2\f$.
    * @param ichan Which of the four pion channels this is for.
    * @return The G function.
    */
   InvEnergy6 gFunction(Energy2 q2, int ichan) const;
 
   /**
    * The d parameter in \f$\rho\f$ the propagator.
    */
   Energy2 DParameter() const;
 
   /**
    * The \f$\frac{dh}{dq^2}\f$ function in the rho propagator evaluated at \f$q^2=m^2\f$.
    */
   double dhdq2Parameter() const;
 
   /**
    * The h function in the \f$\rho\f$ propagator.
    * @param q The scale.
    * @return The h function.
    */
   Energy2 hFunction(const Energy q) const;
 
 private:
   
   /**
    * Interpolating functions for the G functions of hep-ph/0201149
    */
   //@{
   /**
    * The interpolator for the \f$\omega\f$ current.
    */
   Interpolator<double,Energy>::Ptr _Fomega;
 
   /**
    * The interpolator for the three charged pion \f$a_1\f$ current. 
    */
   Interpolator<double,Energy>::Ptr _Fthreec;
 
   /**
    * The interpolator for the one   charged pion \f$a_1\f$ current.
    */
   Interpolator<double,Energy>::Ptr _Fonec;
 
   /**
    * The interpolator for the \f$\sigma\f$ current.
    */
   Interpolator<double,Energy2>::Ptr _Fsigma;
   //@}
 
   /**
    * The charged pion mass
    */
   Energy _mpic;
 
   /**
    * The neutral pion mass
    */
   Energy _mpi0;
 
   /**
    * The mass of the \f$\rho\f$ for the current.
    */
   Energy _rhomass;
 
   /**
    * The mass of the \f$a_1\f$ for the current.
    */
   Energy _a1mass;
 
   /**
    * The mass of the \f$\omega\f$ for the current.
    */
   Energy _omegamass;
 
   /**
    * The mass of the \f$\sigma\f$ for the current.
    */
   Energy _sigmamass;
 
   /**
    * The width for the \f$\rho\f$.
    */
   Energy _rhowidth;
 
   /**
    *  The \f$a_1\f$ width
    */
   Energy _a1width;
 
   /**
    *  The \f$\omega\f$ width.
    */
   Energy _omegawidth;
 
   /**
    *  The \f$\sigma\f$ width.
    */
   Energy _sigmawidth;
 
   /**
    * Mass for the intermediate in the phase-space, this is a technical parameter to
    * improve the phase-space integration efficiency.
    */
   Energy _intmass;
 
   /**
    * Width for the intermediate in the phase-space, this is a technical parameter to
    * improve the phase-space integration efficiency.
    */
   Energy _intwidth; 
 
   /**
    * The \f$z\f$ \f$\sigma\f$ coupling.
    */
   Complex _zsigma;
 
   /**
    * The magnitude of the \f$z\f$ \f$\sigma\f$ coupling.
    */
   double _zmag;
 
   /**
    * The phase of the \f$z\f$ \f$\sigma\f$ coupling.
    */
   double _zphase;
 
   /**
    * The mass parameter for the \f$a_1\f$ form-factor.
    */
   Energy2 _lambda2;
 
   /**
    * The inverse of the mass parameter for the \f$a_1\f$ form-factor.
    */
   InvEnergy2 _onedlam2;
 
   /**
    *  The physical \f$a_1\f$ mass divided by the mass parameter in the 
    *  \f$a_1\f$ form-factor.
    */
   double _a1massolam2;
 
   /**
    * The momentum of the  pions in on-shell \f$\sigma\f$ decay which is used
    * in the calculation of the running \f$\sigma\f$ width.
    */
   vector<Energy> _psigma;
 
   /**
    *  The charged pion mass squared.
    */
   Energy2 _mpic2;
 
   /**
    * The neutral pion mass squared
    */
   Energy2 _mpi02;
 
   /**
    *  The h function evaluated at the \f$\rho\f$ mass.
    */
   Energy2 _hm2;
 
   /**
    * The d parameter for the \f$\rho\f$ width.
    */
   Energy2 _rhoD;
 
   /**
    * The momentum of the pions produced in on-shell \f$rho\f$ decay.
    */
   Energy _prho;
 
   /**
    * \f$\frac{dh}{dq^2}\f$ evaluates at \f$q^2=m^2\f$ for the \f$\rho\f$.
    */
   double _dhdq2m2;
 
   /**
    * Magic number for the omega current.
    */
   InvEnergy _aomega;
 
   /**
    * Magic number for the three charged pion current.
    */
   InvEnergy _athreec;
 
   /**
    * Magic number for the one charged pion current
    */
   InvEnergy _aonec;
 
   /**
    * Magic number for the omega current.
    */
   double _bomega;
 
   /**
    * Magic number for the three charged pion current.
    */
   double _bthreec;
 
   /**
    * Magic number for the one charged pion current
    */
   double _bonec;
 
   /**
    * Magic number for the omega current.
    */
   double _comega;
 
   /**
    * Magic number for the three charged pion current.
    */
   double _cthreec;
 
   /**
    * Magic number for the one charged pion current
    */
   double _conec;
 
   /**
    * magic numbers for the running omega width
    */
   vector<double> _omegaparam;
 
   /**
    * whether or not to initialize the calculation of the \f$a_1\f$ width
    */
   bool _initializea1;
 
   /**
    * use local values of the particle masses
    */
   bool _localparameters;
 
   /**
    * The widths for the interpolation table for the running \f$a_1\f$ width.
    */
   vector<Energy> _a1runwidth;
 
   /**
    * The \f$q^2\f$ values for the interpolation table for the running \f$a_1\f$ width.
    */
   vector<Energy2> _a1runq2;
 
   /**
    * The interpolator for the running \f$a_1\f$ width.
    */
   Interpolator<Energy,Energy2>::Ptr _a1runinter;
 
   /**
    *  The maximum mass of the hadronic system
    */
   Energy _maxmass;
 
   /**
    *  The maximum mass when the running width was calculated
    */
   Energy _maxcalc;
 };
 
 }
 
 #endif /* HERWIG_FourPionNovosibirskCurrent_H */
 

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