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only degraded due to backgrounds from approximately 0.02 to 0.03. 

<img src='content_image/351532.jpg'>

The obtained limits are given for the ratios of observed number of events. Within a real- istic experimental environment one would have to take into account the different detection efficiencies of electrons vs. muons (which are approximately equal in PGS). The difference in energy resolution might also play a role. This effect is expected, however, to be very small, since the resolutions of the reconstructed masses ( m χ 0 T and m$_{χ}$ ± ) are mostly driven by the energy resolution of jets. The ratio of reconstruction efficiencies of electrons vs. muons could be measured to a very high accuracy by comparing e.g. Z → e $^{+}$e − to Z → µ $^{+}$µ − events. With O (10 $^{5}$) such events expected per 1 fb − $^{1}$, the attainable uncertainty of the efficiency ratio is expected to be negligible for our purposes. Thus, while a detailed study of such experimental effects is beyond the scope of this work, we expect the results presented here to be robust. 

