# First Measurements of Absolute Branching Fractions of the ${\Xi }_{c}^{0}$ Baryon at Belle

25 February 2019

Abstract: We present the first measurements of absolute branching fractions of ${\Xi }_{c}^{0}$ decays into ${\Xi }^{-}{\pi }^{+}$, $\Lambda {K}^{-}{\pi }^{+}$, and $p{K}^{-}{K}^{-}{\pi }^{+}$ final states. The measurements are made using a dataset comprising $\left(772±11\right)×{10}^{6}$ $B\overline{B}$ pairs collected at the $\Upsilon \left(4S\right)$ resonance with the Belle detector at the KEKB ${e}^{+}{e}^{-}$ collider. We first measure the absolute branching fraction for ${B}^{-}\to {\overline{\Lambda }}_{c}^{-}{\Xi }_{c}^{0}$ using a missing-mass technique; the result is $B\left({B}^{-}\to {\overline{\Lambda }}_{c}^{-}{\Xi }_{c}^{0}\right)=\left(9.51±2.10±0.88\right)×{10}^{-4}$. We subsequently measure the product branching fractions $B\left({B}^{-}\to {\overline{\Lambda }}_{c}^{-}{\Xi }_{c}^{0}\right)B\left({\Xi }_{c}^{0}\to {\Xi }^{-}{\pi }^{+}\right)$, $B\left({B}^{-}\to {\overline{\Lambda }}_{c}^{-}{\Xi }_{c}^{0}\right)B\left({\Xi }_{c}^{0}\to \Lambda {K}^{-}{\pi }^{+}\right)$, and $B\left({B}^{-}\to {\overline{\Lambda }}_{c}^{-}{\Xi }_{c}^{0}\right)B\left({\Xi }_{c}^{0}\to p{K}^{-}{K}^{-}{\pi }^{+}\right)$ with improved precision. Dividing these product branching fractions by the result for ${B}^{-}\to {\overline{\Lambda }}_{c}^{-}{\Xi }_{c}^{0}$ yields the following branching fractions: $B\left({\Xi }_{c}^{0}\to {\Xi }^{-}{\pi }^{+}\right)=\left(1.80±0.50±0.14\right)%$, $B\left({\Xi }_{c}^{0}\to \Lambda {K}^{-}{\pi }^{+}\right)=\left(1.17±0.37±0.09\right)%$, and $B\left({\Xi }_{c}^{0}\to p{K}^{-}{K}^{-}{\pi }^{+}\right)=\left(0.58±0.23±0.05\right)%$. For the above branching fractions, the first uncertainties are statistical and the second are systematic. Our result for $B\left({\Xi }_{c}^{0}\to {\Xi }^{-}{\pi }^{+}\right)$ can be combined with ${\Xi }_{c}^{0}$ branching fractions measured relative to ${\Xi }_{c}^{0}\to {\Xi }^{-}{\pi }^{+}$ to yield other absolute ${\Xi }_{c}^{0}$ branching fractions.

Published in: Physical Review Letters 122 (2019)