content_image/340438.jpg
and from the Tevatron 8 (from the DØ analysis of Ref. [4] using 5 . 4 fb − 1 and the CDF analysis of Ref. [5] using 4 . 6 fb − 1 of data, respectively for electrons and muons in the final state). The Tevatron limits for the Z ′ B − L boson are shown in table II (for selected masses and couplings). In the same figure we also include for comparison the Tevatron discovery potential at the 

<img src='content_image/340438.jpg'>

integrated luminosities used for the latest published analyses [4, 5] (5 . 4 fb − 1 and 4 . 6 fb − 1 for electrons and muons, respectively) as well as the expected reaches at L = 10 fb − $^{1}$. 

Notice that the Tevatron excluded area are based on the actual data, while the dot-dashed 2 σ curves are our theoretical curves. Thus, if from the one side theory cannot reproduce experiments, from the other side we are comparing two methods of extracting the results. As mentioned previously, figure 3 shows that the procedures used in experimental analyses for the electron channel [4, 6] are not quite optimised for maximizing the signal significance. The alternative analysis described in this work has the potential to improve sensitivities and can be easily developed even further. 

