B_s⁰ to D_s^-a₁^+ decay channel in the B_s⁰-mixing studies

The usefulness of the $B_s^0 \to D_s^-a_1^+, D_s^- \to \phi \pi^- \to K^+K^-\pi^-, a_1^+ \to \rho^0 \pi^+ \to \pi^+ \pi^- \pi^+$ decay chain is investigated for the $B_s$-reconstruction in the future ATLAS $B_s$-mixing experiment. It is shown that this decay channel is almost as suitable for this purpose as previously studied $B_s^0 \to D_s^-\pi^+$.