is larger than about $10^{-7}{\ensuremath{\,\textnormal{s}}}$. Then the stau is metastable, i.e., it usually leaves an LHC detector before decaying.

In this scenario catalyzed big bang nucleosynthesis [@Pospelov:2006sc] leads to an upper bound of roughly $10^4{\ensuremath{\,\textnormal{s}}}$ on the stau lifetime. While this bound can in principle be satisfied by lowering the gravitino mass sufficiently, a short lifetime is also obtained for gravitino masses in the GeV range and a relatively heavy stau [@Pradler:2007is; @Kersten:2007ab] due to the dependence of $\tau_{{\widetilde{\tau}}}$ on ${m_{{{\widetilde{\tau}}}_1}}^{-5}$.

Previous studies of the LHC phenomenology of metastable staus have concentrated on the production via decays of heavier superparticles, assuming specific scenarios for SUSY breaking [@Nisati:1997gb; @Hinchliffe:1998ys; @Ambrosanio:2000ik; @Ambrosanio:2000zu; @Sjolin:2002fx; @Feng:2004mt; @DeRoeck:2005bw; @Ellis:2006vu; @Feng:2009yq; @Feng:2009bd; @Chen:2009gu; @Ito:2009xy; @Heckman:2010xz; @Kitano:2010tt; @Endo:2010ya; @Endo:2011uw]. See also [@Fairbairn:2006gg] for a comprehensive review of the topic. Here we do not restrict ourselves to a specific SUSY-breaking scenario and we focus on the direct production of staus via the neutral current Drell-Yan (DY) process, which possesses interesting properties:

-   The DY contribution is independent of all MSSM parameters except ${m_{{{\widetilde{\tau}}}_1}}$ and the stau mixing angle ${\theta_{{{\widetilde{\tau}}}}}$, enabling a model-independent analysis.

-   The DY process is always present. Together with the previous point, conservatively this leads 