content_image/433576.jpg content_image/433575.jpg content_image/433574.jpg content_image/433577.jpg
with 5 fb − $^{1}$, use madgraph [23] to model the kinemat- ics of the events, pythia [24] for showering and a version of pgs [25] tuned to describe the performance of the CD- FII detector. 

At the LHC, the diboson contribution includes an ad- ditional process, qq → W $^{±}$W $^{±}$q$^{′}$q$^{′}$, which directly pro- duces the ℓ $^{±}$ℓ$^{±}$jj signature. For the LHC, we calculate the size and kinematics of each contribution using mad- graph , use pythia for showering and a version of pgs tuned to describe the performance of the ATLAS detec- tor. 

Figure 3 shows the reconstructed mass shape for N pair production and for the backgrounds in the µ $^{±}$µ$^{±}$jj case. 

## Expected Limits and Discovery Potential 

We perform a binned likelihood fit in the reconstructed N mass, and use the unified ordering scheme [26] to con- 

<img src='content_image/433576.jpg'>

<img src='content_image/433575.jpg'>

struct frequentist intervals. If the N does not exist and no excess is seen, the median expected upper limits on the cross-section are given in Table I and Fig. 4. In 5 fb − $^{1}$, with BR( N → µW ) = 100%, a single Tevatron (LHC) experiment could expect to set a 95% lower limit of m$_{N}$ > 175 (300) GeV. The limits as a function of BR( N → τW ) are given in Fig. 5. If the N does exist, a 3 σ excess would be observed in the regions shown in Fig. 5. 

<img src='content_image/433574.jpg'>

<img src='content_image/433577.jpg'>

The s -channel pair production of heavy Majorana neu- trinos via a Z boson ( Z → NN → WℓWℓ ) is a powerful discovery mode at hadron colliders. With 5 fb − 1 of data, the Tevatron can significantly extend the limits on such neutrinos to 175 GeV/ c $^{2}$, and a 3 σ evidence is possible if 

## CONCLUSIONS 

