Search for ${\Lambda }_b\to \frac{J}{\psi }{\Lambda }^0$ in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}$ TeV

We have searched for the $b$-flavored baryon decay ${\Lambda }_b\to \frac{J}{\psi }{\Lambda }^0$ in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}$ TeV with the Collider Detector at Fermilab (CDF). In the $\frac{J}{\psi }{\Lambda }^0$ invariant-mass distribution we observe a flat distribution and a small number of events, consistent with no signal. Using the $b$-quark cross section measured by the CDF we put an upper limit on the $b\to {\Lambda }_b$ production fraction times the branching ratio $F\left({\Lambda }_b\right)B({\Lambda }_b\to \frac{J}{\psi }{\Lambda }^0)$ of 0.50×${10}^{-3\mathrm{}}$ at 90% confidence level.