/* This file calculates the kaon wavefunction. */

/**************************************************************************/
/*                                                                        */
/* IMPORTANT : all dimensional quantities in this program                 */
/*             are in units GeV                                           */  
/*                                                                        */
/**************************************************************************/


#include <kaon_wavefunction.h>

/* the function kaon_distribution_ampl() returns the 
   kaon distribution amplitude 
   for different forms (choice form = 1 corresponds with asymptotic DA)
   and with the possibility to have a SU(3) symmetry breaking term 
   with adjustable coefficient symm_breaking. 
   The DA is given as function of the quark longitudinal momentum fraction x. 
   !!! Note on convention : normalized to F_KAON !!! */

double kaon_distribution_ampl(int form, double su3_symm_breaking, double x)
{
     return F_KAON * norm_kaon_distribution_ampl(form, su3_symm_breaking, x);
}


/* the function norm_kaon_distribution_ampl() returns the 
   kaon distribution amplitude normalized to 1, 
   as function of the quark longitudinal momentum fraction x */

double norm_kaon_distribution_ampl(int form,double su3_symm_breaking,double x)
{
     double asy, norm;
     asy = 6. * x * (1. - x);

     switch(form)
     {
     case 1 : /* asymptotic DA */
            {
	     return asy;     
             break;
            }
     case 2 : /* CZ type DA, see Kroll et al. PRD55, 4315 (1997) */
            {
             norm = .2;
	     return 1./norm * asy * (0.08 + 0.6 * pow(1. - 2. * x, 2.) 
                                 + 0.25 * pow(1. - 2. * x, 3.) );     
             break;
            }
     case 3 : /* CZ type DA 
                 with adjustable SU(3) symmetry breaking parameter */
            {
             norm = .2;
	     return 1./norm * asy * ( 0.08 + 0.6 * pow(1. - 2. * x, 2.) 
                                    + su3_symm_breaking * pow(1. - 2. * x,3.));
             break;
            }
     }
}


double int_kaon_distribution_ampl_cz(double x)
{
     double asy;
     asy = 6. * x * (1. - x);

     return asy * (0.08 + 0.6 * pow(1. - 2. * x, 2.) 
                        + su3_symm_breaking_s * pow(1. - 2. * x, 3.) ); 
}