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

The DELPHI Collaboration

doi:doi:10.1140/epjc/s2003-01183-7

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2019 Impact factor 4.389

Particles and Fields

Eur. Phys. J. C 28, 155-173 (2003)
DOI: 10.1140/epjc/s2003-01183-7

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

The DELPHI Collaboration

(Received: 6 November 2002 / Revised version: 19 February 2003 / Published online: 31 March 2003 )

Abstract
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 $\mbox{B}^0_d-\overline{\mbox{B}^0_d}$ system was measured to be:

$\begin{displaymath}\Delta m_d = (0.531 \pm 0.025 (stat.) \pm 0.007 (syst.)) \rm ps^{-1}. \end{displaymath}$

The following limit on the width difference of these states was also obtained:

$\begin{displaymath}\vert\Delta\Gamma_{\rm B_d}\vert / \Gamma_{\rm B_d} < 0.18 \mbox{ at } 95\% \mbox{ CL}. \end{displaymath}$

As no evidence for $\mbox{B}^0_s-\overline{\mbox{B}^0_s}$ oscillations was found, a limit on the mass difference of the two physical states was given:

$\begin{displaymath}\Delta m_s > 5.0 \: \rm ps^{-1} \mbox{ at } 95\% \mbox{ CL}. \end{displaymath}$