Search for $\mbox{B}^0_s-\overline{\mbox{B}^0_s}$ oscillations and a measurement of $\mbox{B}^0_d-\overline{\mbox{B}^0_d}$ oscillations using events with an inclusively reconstructed vertex

Neutral B meson oscillations in the $\mbox{B}^0_s-\overline{\mbox{B}^0 _s}$ and $\mbox{B}^0_d-\overline{\mbox{B}^0_d}$ systems were studied using a sample of about 4.0 million hadronic Z decays recorded by the DELPHI detector between 1992 and 2000. Events with a high transverse momentum lepton were removed and a sample of 770 k events with an inclusively reconstructed vertex was selected. The mass difference between the two physical states in the $\mbox{B}^0_d-\over$ system was measured to be: \begin{center} $\Delta m_d = (0.531 \pm 0.025 (stat.) \pm 0.007 (syst.)) \rm ps^{-1}$. \end{center} The following limit on the width difference of these states was also obtained: \begin{center} $|\Delta\Gamma_{\rm B_d}| / \Gamma_{\rm B_d} 0.18$ at 95\% CL. \end{center} The corresponding sensitivity of this analysis is equal to 6.6 ps$^{-1}$.