Measurement of $\Delta m_s$ in the decay $B^0_s \rightarrow D^-_s(K^+K^-\pi^-)\pi^+$ using opposite-side and same-side flavour tagging algorithms

The $B^0_s$-$\overline{B^0_s}$ oscillation frequency $\Delta m_s$is measured on a data sample of 340 pb$^{-1}$ from the LHCb physics run in 2011. A total of 9189 $B^0_s$ signal candidates are reconstructed in the $B^0_s \rightarrow D^-_s \pi^+$ decay, with an average decay time resolution of 45 fs. We established an oscillation signal using for the first time in LHCb the same-side kaon tagging and measured its effective tagging efficiency of $\epsilon_{\text{eff}_\text{SSKT}}$ = 1.3$\pm$ 0.4 %. The most precise value of the oscillation frequency is found to be $\Delta m_s$ = 17.725$\pm$ 0.041(stat) $\pm$0.026 (syst)ps$^{-1}$ using a combination of opposite-side and same-side flavour tagging algorithms.