EvtD0TopipiEta.h

// Model: EvtD0TopipiEta
// This file is an amplitude model for D0 -> pi- pi+ eta.
// The model is from the BESIII Collaboration in Phys. Rev. D 110, L111102 (2024). DOI:  https://doi.org/10.1103/PhysRevD.110.L111102
//
// Permission to include these files in basf2 was generously granted by the BESIII Collaboration.
//
// Please cite the original reference for any public/published results where this model was used.
 
#pragma once
 
#include <EvtGenBase/EvtDecayProb.hh>
 
 
namespace Belle2 {
 
  class EvtD0TopipiEta: public EvtDecayProb {
 
  public:
    EvtD0TopipiEta() {}
    virtual ~EvtD0TopipiEta();
    std::string getName();
    EvtDecayBase* clone();
    void init();
    void initProbMax();
    void decay(EvtParticle* p);
 
  private:
    double calDalEva(double P1[], double P2[], double P3[]);
    EvtComplex Spin_factor(double P1[], double P2[], double P3[], int spin, int flag, double mass_R, double width_R);
 
    double dot(double* a1, double* a2);
    double Qabcs(double sa, double sb, double sc);
    double barrier(double l, double sa, double sb, double sc, double r, double mass);
    void calt1(double daug1[], double daug2[], double t1[]);
    void calt2(double daug1[], double daug2[], double t2[][4]);
 
    double wid(double mass, double sa, double sb, double sc, double r, int l);
    EvtComplex propagatorRBW(double mass, double width, double sa, double sb, double sc, double r, int l);
 
    double h(double m, double q);
    double dh(double mass, double q0);
    double f(double mass, double sx, double q0, double q) ;
    double d(double mass, double q0);
    EvtComplex propagatorGS(double mass, double width, double sa, double sb, double sc, double r, int l);
 
    EvtComplex Flatte_rhoab(double sa, double sb, double sc);
    EvtComplex propagatorFlatte(double mass, double width, double sx, double* sb, double* sc);
 
    double rho[24];
    double phi[24];
    double mrho, ma0;
    double Grho, Ga0;
    double mpi, mD, sD, spi, snk, sck, scpi, snpi, seta;
    double pi;
    EvtComplex ci;
    EvtComplex one;
    int G[4][4];
  };

} // Belle 2 Namespace