We pursue the study of SU(2) Euclidean Yang-Mills theory in the maximal
Abelian gauge by taking into account the effects of the Gribov horizon. The
Gribov approximation, previously introduced in [1], is improved through the
introduction of the horizon function, which is constructed under the
requirements of localizability and renormalizability. By following Zwanziger's
treatment of the horizon function in the Landau gauge, we prove that, when cast
in local form, the horizon term of the maximal Abelian gauge leads to a
quantized theory which enjoys multiplicative renormalizability, a feature which
is established to all orders by means of the algebraic renormalization.
Furthermore, it turns out that the horizon term is compatible with the local
residual U(1) Ward identity, typical of the maximal Abelian gauge, which is
easily derived. As a consequence, the nonrenormalization theorem,
Z_{g}Z_{A}^{1/2}=1, relating the renormalization factors of the gauge coupling
constant Z_{g} and of the diagonal gluon field Z_{A}, still holds in the
presence of the Gribov horizon. Finally, we notice that a generalized dimension
two gluon operator can be also introduced. It is BRST invariant on-shell, a
property which ensures its multiplicative renormalizability. Its anomalous
dimension is not an independent parameter of the theory, being obtained from
the renormalization factors of the gauge coupling constant and of the diagonal
antighost field.Comment: 31 page