QCD partition function in the external field in the covariant gauge
  The QCD partition function in the external stationary gluomagnetic field is computed in the third order in external field invariants in arbitrary dimension and arbitrary covariant gauge. The contributions proportional to third order invariants in gluon field strength are shown to be dependent on covariant quantum gauge fixing parameter \alpha 
Andrei Leonidov, Vladimir Nechitailo