#### ${{\mathit B}_{{{s}}}^{0}}-{{\overline{\mathit B}}_{{{s}}}^{0}}$ MIXING

For a discussion of ${{\mathit B}_{{{s}}}^{0}}-{{\overline{\mathit B}}_{{{s}}}^{0}}$ mixing see the note on “${{\mathit B}^{0}}-{{\overline{\mathit B}}^{0}}$ Mixing” in the ${{\mathit B}^{0}}$ Particle Listings above.
${{\mathit \chi}_{{{s}}}}$ is a measure of the time-integrated ${{\mathit B}_{{{s}}}^{0}}-{{\overline{\mathit B}}_{{{s}}}^{0}}$ mixing probability that produced ${{\mathit B}_{{{s}}}^{0}}({{\overline{\mathit B}}_{{{s}}}^{0}}$) decays as a ${{\overline{\mathit B}}_{{{s}}}^{0}}({{\mathit B}_{{{s}}}^{0}}$). Mixing violates $\Delta \mathit B{}\not=$2 rule.
${{\mathit \chi}_{{{s}}}}$ = ${\mathit x{}^{2}_{\mathit s}\over 2(1+\mathit x{}^{2}_{\mathit s})}$

$\mathit x_{\mathit s}$ = ${\Delta {\mathit m}_{{{\mathit B}_{{{s}}}^{0}}}\over \Gamma _{{{\mathit B}_{{{s}}}^{0}}}}$ = (${\mathit m}_{\mathrm {{{\mathit B}}{}^{0}_{{{\mathit s}} {{\mathit H}}}}}$ $-$ ${\mathit m}_{\mathrm {{{\mathit B}}{}^{0}_{{{\mathit s}} {{\mathit L}}}}}){\mathit \tau}_{{{\mathit B}_{{{s}}}^{0}}}$ ,
where $\mathit H$, $\mathit L$ stand for heavy and light states of two ${{\mathit B}_{{{s}}}^{0}}$ $\mathit CP$ eigenstates and ${\mathit \tau}_{{{\mathit B}_{{{s}}}^{0}}}$ = ${1\over 0.5 (\Gamma _{{{\mathit B}}{}^{0}_{{{\mathit s}} {{\mathit H}}}}+\Gamma _{{{\mathit B}}{}^{0}_{{{\mathit s}} {{\mathit L}}}})}$.

#### $\mathit x_{\mathit s}$ = $\Delta {\mathit m}_{{{\mathit B}_{{{s}}}^{0}}}/\Gamma _{{{\mathit B}_{{{s}}}^{0}}}$

Derived from the results on $\Delta {\mathit m}_{{{\mathit B}_{{{s}}}^{0}}}$ and “OUR EVALUATION” of the ${{\mathit B}_{{{s}}}^{0}}$ mean lifetime.

VALUE
 $\bf{ 26.99 \pm0.09}$ OUR EVALUATION  $~~$(Produced by HFLAV)
Conservation Laws:
$\Delta \mathit B$ = 2 VIA MIXING