We improve the theoretical predictions for the production of extra neutral gauge bosons at hadron colliders by implementing the Z bosons in the MC@NLO generator and by computing their differential and total cross sections in joint p_T and threshold resummation. The two improved predictions are found to be in excellent agreement with each other for mass spectra, p_T spectra, and total cross sections, while the PYTHIA parton and ``power shower predictions usually employed for experimental analyses show significant shortcomings both in normalization and shape. The theoretical uncertainties from scale and parton density variations and non-perturbative effects are found to be 9%, 8%, and less than 5%, respectively, and thus under good control. The implementation of our improved predictions in terms of the new MC@NLO generator or resummed K factors in the analysis chains of the Tevatron and LHC experiments should be straightforward and lead to more precise determinations or limits of the Z boson masses and/or couplings.
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