to an assured discovery potential and strict exclusion limits in a class of scenarios characterized only by ${m_{{{\widetilde{\tau}}}_1}}$ and ${\theta_{{{\widetilde{\tau}}}}}$.

Thus, it is natural to ask for the required luminosity which provides this robust exclusion limit (and the discovery reach) in the $7{\ensuremath{\,\textnormal{TeV}}}$ and $14{\ensuremath{\,\textnormal{TeV}}}$ LHC run. Although the DY production of staus has been included in some studies [@Rajaraman:2006mr; @Rajaraman:2007ae; @Endo:2011uw], the focus of these works has been different and—to our knowledge—this question has only been addressed in a brief remark in the review [@Raklev:2009mg], where the aim is only a rough estimate with fairly conservative assumptions. Here, we perform a careful analysis, in particular examining the dependence on the imposed cuts and using the proper statistics for small event numbers. We also take into account the latest information from the LHC experiments on discriminating heavy stable charged particles from muons. We find that the opposite-sign stau pair from DY production allows for a clean signal region up to very large integrated luminosities. Thus, in spite of its small cross section the DY process is able to provide an interesting discovery and exclusion potential, even for relatively large stau masses and significantly better than estimated in [@Raklev:2009mg].

The paper 