Implementation of non-linear gauge-fixing in FeynArts package

Feynman rules for the Standard Model including non-linear gauges are derived and implemented in the FeynArts package. The calculations using FeynArts with the new rules show that tree-level amplitudes are gauge invariant and that renormalization is not spoiled for one-loop calculations. The FeynArts model files are available at http://www.fi.lt/~garfield/SM/