jet}}=\sqrt{\Delta\eta_{\mu, {\rm jet}}^2+\Delta\phi_{\mu, {\rm jet}}^2}>0.5$ for jets with $p_{\rm T}>50{\ensuremath{\,\textnormal{GeV}}}$.

With the $p_{\rm T}$- and the isolation cut, a sufficient rejection of the $b$- and $c$-contributions should easily be obtained. This is why we refrain from running a detector simulation for this issue. All the same we made no effort to specify the isolation algorithm. Instead we apply the respective cuts directly on the remaining background (and signal) at the level of the <span style="font-variant:small-caps;">Pythia</span> Les Houches Event output. The $p_{\rm T}$-cut also rejects muon pairs from on-shell $Z$ decay. Therefore, an additional cut on the invariant mass of the muon pair, which was used in [@Rajaraman:2006mr], would not have a significant effect.

As the remaining background, we consider di-muons from the DY process and from $t\bar{t}$-production. We include contributions up to order $\alpha_{\rm s}^2$ (two jets) in the case of the DY process and $\alpha_{\rm s}^3$ (three jets) in the case of $t\bar{t}$-production and generate $2\times 10^{5}$ unweighted events for the analysis. The total normalization of the cross section was fixed from the leading order DY di-muon production (without jets) from MadEvent multiplied by a constant $K$-factor, conservatively chosen to be $1.4$, to account for next-to-leading order (NLO) corrections. 