Measurement of inclusive $D_s$, $D^0$, and $J/\psi$ rates and determination of the $B_s^{(*)} \bar{B}_s^{(*)}$ production fraction in $b \bar{b}$ events at the Y(5S) resonance

The inclusive production of $D_s$, $D^0$, and $J/\psi$ mesons is studied using a 1.86 fb$^{-1}$ data sample collected on the $\Upsilon$(5S) resonance by the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. The number of $b\bar{b}$ events in the $\Upsilon$(5S) data sample is determined. We measure the branching fractions $B(\Upsilon({\rm 5S}) \to D_s X) / 2 = (23.6 \pm 1.2 \pm 3.6)%$, $B(\Upsilon({\rm 5S}) \to D^0 X) / 2 = (53.8 \pm 2.0 \pm 3.4)%$}, and $B(\Upsilon({\rm 5S}) \to J/\psi X) / 2 = (1.030 \pm 0.080 \pm 0.067)%$. From the $D_s$ and $D^0$ inclusive branching fractions the ratio $f_s = (18.0 \pm 1.3 \pm 3.2)%$} of $B_s^{(*)} \bar{B}_s^{(*)}$ to the total $b\bar{b}$ quark pair production at the $\Upsilon$(5S) energy is obtained in a model-dependent way.