Evidence for Z $\rightarrow$ $\tau^{+} \tau^{-}$ production in 7 TeV proton-proton collisions at CMS

The reconstruction of tau leptons in a hadronic environment can be challenging, yet it is important for many searches for new particles as well as studies of Standard Model processes. The production of Z bosons decaying into tau pairs serves as a ``standard candle'' for the commissioning of the tau reconstruction as well as test bench for analogous H $\rightarrow$ $\tau^{+} \tau^{-}$ decays. Proton-proton collision events collected with the CMS experiment at the LHC corresponding to an integrated luminosity of 70 nb$^{-1}$ are used to compare the performances of the Hadron plus Strip tau identification algorithm in data events and MC simulations considering the Z $\rightarrow$ $\tau^{+} \tau^{-}$ process. The efficiency of the $\tau$ identification algorithm fully satisfies the CMS requirements as demonstrated by the successful identification of the first Z $\rightarrow$ $\tau^{+} \tau^{-} \rightarrow \mu$ + $\tau_{\, \rm had}$ candidate event, which is also presented here.