Renormalizability of the dimension two gluon operator $A^{2}$ in a class   of nonlinear covariant gauges
  In this work we discuss a class of nonlinear covariant gauges for Yang-Mills theories which enjoy the property of being multiplicatively renormalizable to all orders. This property follows from the validity of a linearly broken identity, known as the ghost Ward identity. Furthermore, thanks to this identity, it turns out that the local composite dimension two gluon operator $A_{\mu}^{a}A_{\mu}^{a}$ can be introduced in a mulptiplicatively renormalizable way. 
V. E. R. Lemes, R. F. Sobreiro, S. P. Sorella