The $J/\psi \to \mu\mu$ selection

This note presents a possible selection algorithm for \jpsimumu at LHCb with a total selection efficiency of $\epsilon_{total} = 5.11\% \pm 0.07\%$ for inclusive \jpsi events.The retention rates for $b$-inclusive and minimum bias events are $RR_{b-\incl} = (1.26 \pm 0.08) \times 10^{-3}$ and $RR_{MB} = (0.1 \pm 0.2) \times 10^{-4}$. The expected annual number of \jpsi events is $(2.29 \pm 0.03) \times 10^{9}$. The reconstructed mass for a sample of $100 \kilo$ inclusive \jpsi events is $M_{J/\psi} = 3096.33 \pm 0.07 \mevctwo$ with a mass resolution of $\sigma_{J/\psi} = 9.943 \pm 0.058 \mevctwo$.