# use_gfermi_scheme_rcl¶

use_gfermi_scheme_rcl(g=None, a=None)

Sets the EW renormalization scheme to the gfermi scheme.

Parameters: g (float) – Sets the value of the Fermi constant to g a (float) – Sets value of $$\alpha$$ to a

Either g or a can be non-zero, but not both at the same time. If neither g nor a are set the hard-coded (default) value for $$\alpha$$ is used.

Note

In Recola2 the value for $$G_\mathrm{F}$$ is translated to $$\alpha$$ according to $$\alpha = \frac{\sqrt{2}G_\mathrm{F}}{\pi} M_\mathrm{W}^2\left(1-\frac{M_\mathrm{W}^2}{M_\mathrm{Z}^2}\right)$$ with the currently set values for $$M_\mathrm{Z}$$ and $$M_\mathrm{W}$$. This behaviour is different from Recola where subsequently updated values (via calls to set_pole_mass_z_rcl() and set_pole_mass_w_rcl()) are used. For this reason, we recommend passing $$\alpha$$ directly rather than $$G_\mathrm{F}$$.