/* This file calculates the rho, omega and phi wavefunctions. */

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


#include <rho_wavefunction.h>

/* the function rho_distr_ampl() returns the 
   asymptotic rho distribution amplitude 
   as function of the quark longitudinal momentum fraction z */

double rho_distr_ampl(double z)
{
     int wavefunction; 
     double asy;
     
     asy = F_RHO/(2. * sqrt(6.)) * 6. * z * (1. - z);
     
     wavefunction = 1;

     switch(wavefunction)
     {
     case 1 : /* asymptotic distribution amplitude */
            {
            return asy;
            break;
            }
     case 2 : /* CZ distribution amplitude */
            {
            return asy * 5. * pow(1. - 2. * z, 2.);
            break;
            }
     case 3 : /* Ball-Braun distribution amplitude */
            {
            double xi, a2;
            xi = 2. * z - 1.;
            a2 = 0.18;
            
            return 6. * z * (1. - z) 
                   * (1. + a2 * 15./2. * (pow(xi,2.) - .2) );
            break;
            }
     }            

}


/* The function rho_wavef_impactpar() returns the rho wavefunction 
   as function of the quark longitudinal momentum fraction x and 
   as function of the transverse distance b (in GeV^-1)
   between the quark and antiquark. 
   To model the transverse momentum dependence, a gaussian ansatz is used. */

double rho_wavef_impactpar(double x, double b)
{
     double avmom_sqr;

     avmom_sqr = 0.67;  /* average squared transverse 
                           quark momentum in rho wavefunction in units GeV^2.
                           Same value is taken as for pion wavefunction */
   
     return 4. * PI * rho_distr_ampl(x) 
            * exp(- .5 * avmom_sqr * x * (1. - x) * pow(b,2.));        
}


/* The function rho_wavef_momspace() returns the rho wavefunction 
   in momentum space as function of 
   the quark longitudinal momentum fraction x and as function of 
   the transverse momentum k_perp between the quark and antiquark. 
   To model the transverse momentum dependence, a gaussian ansatz is used. */

double rho_wavef_momspace(double x, double k_perp)
{
     double avmom_sqr;

     avmom_sqr = 0.67;  /* average squared transverse 
                           quark momentum in rho wavefunction in units GeV^2.
                           Same value is taken as for pion wavefunction */

     return 8. * pow(PI,2.) / avmom_sqr
            * rho_distr_ampl(x) / (x * (1. - x)) 
            * exp(- .5 * pow(k_perp,2.)/(avmom_sqr * x * (1. - x)) );
        
}


/***************************************************************************/


/* the function omega_distr_ampl() returns the 
   asymptotic omega distribution amplitude 
   as function of the quark longitudinal momentum fraction z */

double omega_distr_ampl(double z)
{
     int wavefunction; 
     double asy;
     
     asy = F_OMEGA/(2. * sqrt(6.)) * 6. * z * (1. - z);
     
     wavefunction = 1;

     switch(wavefunction)
     {
     case 1 : /* asymptotic distribution amplitude */
            {
            return asy;
            break;
            }
     case 2 : /* CZ distribution amplitude */
            {
            return asy * 5. * pow(1. - 2. * z, 2.);
            break;
            }
     }            

}


/* The function omega_wavef_impactpar() returns the omega wavefunction 
   as function of the quark longitudinal momentum fraction x and 
   as function of the transverse distance b (in GeV^-1)
   between the quark and antiquark. 
   To model the transverse momentum dependence, a gaussian ansatz is used. */

double omega_wavef_impactpar(double x, double b)
{
     double avmom_sqr;

     avmom_sqr = 0.67;  /* average squared transverse 
                           quark momentum in omega wavefunction in units GeV^2.
                           Same value is taken as for pion wavefunction */
   
     return 4. * PI * omega_distr_ampl(x) 
            * exp(- .5 * avmom_sqr * x * (1. - x) * pow(b,2.));        
}


/* The function omega_wavef_momspace() returns the omega wavefunction 
   in momentum space as function of 
   the quark longitudinal momentum fraction x and as function of 
   the transverse momentum k_perp between the quark and antiquark. 
   To model the transverse momentum dependence, a gaussian ansatz is used. */

double omega_wavef_momspace(double x, double k_perp)
{
     double avmom_sqr;

     avmom_sqr = 0.67;  /* average squared transverse 
                           quark momentum in omega wavefunction in units GeV^2.
                           Same value is taken as for pion wavefunction */

     return 8. * pow(PI,2.) / avmom_sqr
            * omega_distr_ampl(x) / (x * (1. - x)) 
            * exp(- .5 * pow(k_perp,2.)/(avmom_sqr * x * (1. - x)) );
        
}


/***************************************************************************/

/* the function phi_distr_ampl() returns the 
   asymptotic phi distribution amplitude 
   as function of the quark longitudinal momentum fraction z */

double phi_distr_ampl(double z)
{
     int wavefunction; 
     double asy;
     
     asy = F_PHI/(2. * sqrt(6.)) * 6. * z * (1. - z);
     
     wavefunction = 1;

     switch(wavefunction)
     {
     case 1 : /* asymptotic distribution amplitude */
            {
            return asy;
            break;
            }
     case 2 : /* CZ distribution amplitude */
            {
            return asy * 5. * pow(1. - 2. * z, 2.);
            break;
            }
     }            

}


/* The function phi_wavef_impactpar() returns the phi wavefunction 
   as function of the quark longitudinal momentum fraction x and 
   as function of the transverse distance b (in GeV^-1)
   between the quark and antiquark. 
   To model the transverse momentum dependence, a gaussian ansatz is used. */

double phi_wavef_impactpar(double x, double b)
{
     double avmom_sqr;

     avmom_sqr = 0.67;  /* average squared transverse 
                           quark momentum in phi wavefunction in units GeV^2.
                           Same value is taken as for pion wavefunction */
   
     return 4. * PI * phi_distr_ampl(x) 
            * exp(- .5 * avmom_sqr * x * (1. - x) * pow(b,2.));        
}


/* The function phi_wavef_momspace() returns the phi wavefunction 
   in momentum space as function of 
   the quark longitudinal momentum fraction x and as function of 
   the transverse momentum k_perp between the quark and antiquark. 
   To model the transverse momentum dependence, a gaussian ansatz is used. */

double phi_wavef_momspace(double x, double k_perp)
{
     double avmom_sqr;

     avmom_sqr = 0.67;  /* average squared transverse 
                           quark momentum in phi wavefunction in units GeV^2.
                           Same value is taken as for pion wavefunction */

     return 8. * pow(PI,2.) / avmom_sqr
            * phi_distr_ampl(x) / (x * (1. - x)) 
            * exp(- .5 * pow(k_perp,2.)/(avmom_sqr * x * (1. - x)) );
        
}