The Nielsen Identities for the generalized $R_\xi$-gauge
  We show that it is possible, in opposition to a previous conjecture, to derive a Nielsen identity for the effective action in the case of the generalized $R_\xi $-gauge, where the gauge function explicitly depends on the gauge parameter $\xi $. Also the Nielsen identity for the effective potential is verified to one-loop in the Abelian Higgs model and the corresponding identity for the physical Higgs mass is derived. 
Carlos Contreras and Lautaro Vergara