Observation of the Decay ${\Omega }_c^0\to {\Omega }^{-}{e}^{+}{\nu }_e$

Using the CLEO detector at the Cornell Electron Storage Ring we have observed the ${\Omega }_c^0$ ($css$ ground state) in the decay ${\Omega }_c^0\to {\Omega }^{-}{e}^{+}{\nu }_e$. We find a signal of $11.4\pm 3.8\mathrm{(}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{)}$ events. The probability that we have observed a background fluctuation is $7.6\times {10}^{-5}$. We measure $B({\Omega }_c^0\to {\Omega }^{-}{e}^{+}{\nu }_e)·\sigma (e^{+}{e}^{-}\to {\Omega }_c^{0}X)=\mathbf{(}42.2\pm 14.1\mathrm{(}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{)}\pm 5.7\mathrm{(}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{)}\mathbf{)}\mathrm{f}\mathrm{b}$ and $R=\frac{\Gamma ({\Omega }_c^0\to {\Omega }^{-}{\pi }^{+})}{\Gamma ({\Omega }_c^0\to {\Omega }^{-}e{\nu }_e)}=00.41\pm 0.19(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{)}\pm 0.04(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{)}$. This is the first statistically significant observation of an individual decay mode of the ${\Omega }_c^0$ in $e^{+}{e}^{-}$ annihilation and the first example of a baryon decaying via $\beta$ emission, where no quarks from the first generation participate in the reaction.

Figure 1

Invariant mass of ${\Lambda }^0{K}^{-}$ combinations.

Figure 2

The invariant mass of ${\Lambda }^0{K}^{-}$ pairs for events with (a) an $e^{+}$ (that is, RS events) and (b) an $e^{-}$ (that is, WS events) satisfying the selection criteria described in the text.

Figure 3

${\Omega }^{-}{e}^{+}$ invariant mass distribution for events in the signal region (solid line) and Monte Carlo simulation (dashed line).