(B_s^0 \to D_s^-a_1^+(D_s^- \to \phi \pi^-, D_s^- \to K^{0}K^-)\) decay channel in the ATLAS \(B_s^0\)-mixing studies

It is shown, using a track-level simulation, that the use of the \(D_s^- \to K^{*0}K^-\) decay channel for \(D_s^-\) reconstruction, in additioon with the previously studied \(D_s^- \to \phi \pi^-\) mode, enables two fold gain in the ATLAS \(B_s^0\)-mixing signal statistics through \(B_s^0 \to D_s^-a_1\) \(B_s^0\)-decay channel. A new modification of the amplitude fit method is suggested for the \(x_s\) determination. Some general aspects of the \(B_s^0\)-mixing phenomenon is illustrated by pictures of Casimir Malevich, Maurits Cornelis Escher and Salvador Dali.