EIC code displayed by LXR master/​include/​Herwig/​Decay/​WeakCurrents/​FivePionCurrent.h	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2026-08-06 09:24:04

 // -*- C++ -*-
 //
 // FivePionCurrent.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_FivePionCurrent_H
 #define HERWIG_FivePionCurrent_H
 //
 // This is the declaration of the FivePionCurrent class.
 //
 
 #include "WeakCurrent.h"
 #include "ThePEG/Helicity/epsilon.h"
 
 namespace Herwig {
 
 using namespace ThePEG;
 
 /**
  * Here is the documentation of the FivePionCurrent class.
  *
  * @see \ref FivePionCurrentInterfaces "The interfaces"
  * defined for FivePionCurrent.
  */
 class FivePionCurrent: public WeakCurrent {
 
 public:
 
   /**
    * The default constructor.
    */
   FivePionCurrent();
 
   /** @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.
    * @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. 
    * @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. 
    * @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;
 
 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:
 
   /**
    *  Methods to calculate the Breit-Wigner distributions for the various
    *  mesons.
    */
   //@{
   /**
    * Breit-Wigner for the \f$\rho\f$.
    * @param scale The virtual mass
    */
   Complex rhoBreitWigner(Energy2 scale) const {
     Energy2 m2=sqr(_rhomass);
     return m2/(m2-scale-Complex(0.,1.)*_rhomass*_rhowidth);
   }
 
   /**
    * Breit-Wigner for the \f$a_1\f$.
    * @param scale The virtual mass
    */
   Complex a1BreitWigner(Energy2 scale) const {
     Energy2 m2=sqr(_a1mass);
     return m2/(m2-scale-Complex(0.,1.)*_a1mass*_a1width);
   }
   
   /**
    * Breit-Wigner for the \f$\omega\f$.
    * @param scale The virtual mass
    */
   Complex omegaBreitWigner(Energy2 scale) const {
     Energy2 m2=sqr(_omegamass);
     return m2/(m2-scale-Complex(0.,1.)*_omegamass*_omegawidth);
   }
 
   /**
    * Breit-Wigner for the \f$\sigma\f$.
    * @param scale The virtual mass
    */
   Complex sigmaBreitWigner(Energy2 scale) const {
     Energy2 m2=sqr(_sigmamass);
     return m2/(m2-scale-Complex(0.,1.)*_sigmamass*_sigmawidth);
   }
   //@}
 
   /**
    *  Currents for the different channels
    */
   //@{
   /**
    * The \f$\rho\omega\f$ current
    * @param iopt Option for the inclusion of \f$\rho\f$ Breit-Wigner terms in the 
    * \f$\omega\f$ decay piece
    * @param Q The total momentum for the current
    * @param q1 The first momentum
    * @param q2 The first momentum
    * @param q3 The first momentum
    * @param q4 The first momentum
    * @param q5 The first momentum
    */
   LorentzVector<complex<InvEnergy2> >
   rhoOmegaCurrent(unsigned int iopt,
           const Lorentz5Momentum & Q,
           const Lorentz5Momentum & q1,
           const Lorentz5Momentum & q2,
           const Lorentz5Momentum & q3,
           const Lorentz5Momentum & q4,
           const Lorentz5Momentum & q5) const {
     // prefactor
     complex<InvEnergy7> pre(_preomega*a1BreitWigner(Q.m2())*
                 omegaBreitWigner((q1+q2+q3).m2())*
                 rhoBreitWigner((q4+q5).m2()));
     // omega piece
     Complex omega(-1.);
     if(_rhoomega) {
       if(iopt==1)      omega=rhoBreitWigner((q2+q3).m2());
       else if(iopt==2) omega=rhoBreitWigner((q1+q3).m2());
       else if(iopt==3) omega=rhoBreitWigner((q1+q2).m2());
       else            
     omega=rhoBreitWigner((q2+q3).m2())+rhoBreitWigner((q1+q3).m2())+
       rhoBreitWigner((q1+q2).m2());
     }
     LorentzVector<complex<Energy3> > omegacurrent(Helicity::epsilon(q1,q2,q3));
     LorentzVector<complex<InvEnergy2> > output =
       pre * omega * Helicity::epsilon(q4-q5,omegacurrent,Q);
     return output;
   }
   
   /**
    *  The \f$a_1\sigma\f$ current
    * @param iopt Option for the inclusion of \f$\rho\f$ Breit-Wigner terms in the 
    * \f$a_1\f$ decay piece
    * @param Q The total momentum for the current
    * @param q1 The first momentum
    * @param q2 The first momentum
    * @param q3 The first momentum
    * @param q4 The first momentum
    * @param q5 The first momentum
    */
   LorentzVector<complex<InvEnergy2> > 
   a1SigmaCurrent(unsigned int iopt,
          const Lorentz5Momentum & Q,
          const Lorentz5Momentum & q1,
          const Lorentz5Momentum & q2,
          const Lorentz5Momentum & q3,
          const Lorentz5Momentum & q4,
          const Lorentz5Momentum & q5) const {
     Lorentz5Momentum pa1(q1+q2+q3);pa1.rescaleMass();
     Energy2 ma12(pa1.m2());
     complex<InvEnergy3> pre(_presigma*a1BreitWigner(Q.m2())*a1BreitWigner(ma12)*
                 sigmaBreitWigner((q4+q5).m2()));
     Energy2 pdot[2]={q2*(q1-q3),q1*(q2-q3)};
     LorentzPolarizationVectorE rho[2] = 
       {(pdot[0]/ma12*pa1-q1+q3)*rhoBreitWigner((q1+q3).m2()),
        (pdot[1]/ma12*pa1-q2+q3)*rhoBreitWigner((q2+q3).m2())};
     LorentzPolarizationVectorE total;
     if(iopt==1)      total = rho[0];
     else if(iopt==2) total = rho[1];
     else             total = rho[0]+rho[1];
     Complex qdot = total * Q / Q.m2();
     LorentzPolarizationVectorE cq(Q);
     cq = cq * qdot;
     cq -= total;
     return pre * cq;
   }
   //@}
 
 protected:
 
   /** @name Clone Methods. */
   //@{
   /**
    * Make a simple clone of this object.
    * @return a pointer to the new object.
    */
   virtual IBPtr clone() const {return new_ptr(*this);}
 
   /** 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 {return new_ptr(*this);}
   //@}
 
 protected:
 
   /** @name Standard Interfaced functions. */
   //@{
   /**
    * Initialize this object after the setup phase before saving an
    * 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.
    */
   FivePionCurrent & operator=(const FivePionCurrent &) = delete;
 
 private:
 
   /**
    * The masses and widths of the intermediate particles 
    */
   //@{
   /**
    * 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;
   //@}
 
   /**
    * use local values of the particle masses
    */
   bool _localparameters;
 
   /**
    *  Option for the treatment of \f$\rho\f$ Breit-Wigners in \f$\omega\f$ decay
    */
   bool _rhoomega;
 
   /**
    *  Normalisation parameters for the different currents
    */
   //@{
   /**
    *  The \f$c\f$ parameter
    */
   Energy2 _c;
 
   /**
    *  The \f$c_0\f$ parameter
    */
   double _c0;
 
   /**
    *  The \f$f_{\omega\rho\pi}\f$ parameter
    */
   InvEnergy _fomegarhopi;
 
   /**
    * The \f$g_{\rho\pi\pi}\f$ parameter
    */
   double _grhopipi;
 
   /**
    * The \f$G_{a\rho\pi}\f$ parameter
    */
   Energy _garhopi;
 
   /**
    *  The \f$f_{aaf}\f$ parameter
    */
   Energy _faaf;
 
   /**
    *  The \f$f_{f\pi\pi}\f$ parameter
    */
   Energy _ffpipi;
   //@}
 
   /**
    *  Values cached to avoid unnessacary calculations
    */
   //@{
   /**
    *  Prefactor for the \f$\rho\omega\f$ current
    */
   InvEnergy7 _preomega;
 
   /**
    *  Prefactor for the \f$a_1\sigma\f$ current
    */
   InvEnergy3 _presigma;
   //@}
 };
 
 }
 
 #endif /* HERWIG_FivePionCurrent_H */

This page was automatically generated by the 2.3.7 LXR engine. The LXR team