First measurements of branching fractions of $\Xi_c^{0} \to \Lambda \pi^{0}$, $\Xi_c^{0} \to \Lambda \eta$, and $\Xi_c^0 \to \Lambda \eta'$ decays using Belle and Belle~II data
| Abstract | Using data samples of 988.4~fb$^{-1}$ and 427.9~fb$^{-1}$ collected with the Belle and \belletwo detectors, we present a study of the singly Cabibbo-suppressed decays $\Xi_c^{0} \to \Lambda \eta$, $\Lambda \eta'$, and $\Lambda \pi^0$. {We present an observation of the decay $\Xi_c^0 \to \Lambda \eta$ and evidence of the decay $\Xi_c^0 \to \Lambda \eta'$, {with} the corresponding branching {ratios} determined to be ${\mathcal{B}(\Xi_c^0 \to \Lambda \eta)}/{\mathcal{B}(\Xi_c^0 \to \Xi^- \pi^+)}= (4.16 \pm 0.91 \pm {0.23})\%$ and ${\mathcal{B}(\Xi_c^0 \to \Lambda \eta')}/{\mathcal{B}(\Xi_c^0 \to \Xi^- \pi^+)}= (2.48 \pm 0.82 \pm {0.12})\%$, respectively. We find no significant signal in the $\Xi_c^0 \to \Lambda \pi^0$ decay mode and set an upper limit at the 90\% {credibility} level of ${\mathcal{B}(\Xi_c^0 \to \Lambda \pi^0)}/{\mathcal{B}(\Xi_c^0 \to \Xi^- \pi^+)}< {3.5\%}$. Multiplying these ratios by the world-average branching fraction of the normalization channel, $\mathcal{B}(\Xi_c^0 \to \Xi^- \pi^+)=(1.43 \pm 0.27)\%$, we obtain the absolute branching fractions of $\mathcal{B}(\Xi_c^0 \to \Lambda \eta)= (5.95 \pm 1.30 \pm {0.32} \pm 1.13) \times 10^{-4}$, $\mathcal{B}(\Xi_c^0 \to \Lambda \eta')= (3.55 \pm 1.17 \pm {0.17} \pm 0.68) \times 10^{-4}$, and an upper limit at the 90\% {credibility} level on the absolute branching fraction of $\mathcal{B}(\Xi_c^0 \to \Lambda \pi^0)< {5.2} \times 10^{-4}$.} {The quoted} first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on $\mathcal{B}(\Xi_c^0 \to \Xi^{-} \pi^{+})$. {These results are consistent with most of the theoretical predictions and provide information for the understanding of the underlying decay mechanisms. |
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| Tags | Belle Run 1 Run 2 (partial) |
| Working group | Charm |
| Principal authors | @ Jianshe Zhou, Junxi Cui, Chengping Shen |
| Reference | submitted to PRD |
| Links | arXiv:2510.20882, |