use_gfermi_scheme_rcl(g=None, a=None)

Sets the EW renormalization scheme to the gfermi scheme.

  • 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.


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 \(G_\mathrm{F}\).