/* This is the header file for the functions that specify the
   QCD strong coupling constant. */

#ifndef strong_coupling_h
#define strong_coupling_h

#include <default.h>
#include <complex.h>

#define ALPHA_S 0.56         /* fixed value of alpha_s at scale 
                               around 1 GeV^2 : PRD54 (1996) 2182 */
#define LAMBDA1_QCD 0.200   /* 0.200 GeV */
                            /* lambda_qcd */

#define N_FLAVOURS 3.        /* number of flavours */

#define EULER 0.577216

double alpha_strong(int choice, double Q_sqr);

#endif