Detailed descriptions:

extern const double a_e ;

The magnetic momentum anomaly for electrons, no dimension

extern const double a_p ;

The magnetic momentum anomaly for protons, no dimension

extern const double alpha ;

The fine structure constant, no dimension

extern const double c ;

The velocity of light in m/s

extern const double e ;

The value of e

extern const double epsilon_0 ;

The permittivity of vacuum in As/Vm

extern const double h_bar ;

The reduced Planck constant in GeVs

extern const double lamda_e ;

The reduced Compton wave length for electrons in m

extern const double lamda_p ;

The reduced Compton wave length for protons in m

extern const double log10e ;

The logarithm of e to the base 10

extern const double m_e ;

The electron rest mass in GeV

extern const double m_p ;

The proton rest mass in GeV

extern const double mu_0 ;

The permeability of vacuum in Vs/Am

extern const double pi ;

The value of \pi

extern const double q_e ;

The elementary charge in As

extern const double r_e ;

The classical electron radius in m

extern const double r_p ;

The classical proton radius in m

extern const double two_pi ;

The value of 2 \pi

extern const double u_two_pi ;

The value of 1 / (2 \pi)