First measurements of the branching fractions for the decay modes ${\Xi }_c^0\to \Lambda \eta$ and ${\Xi }_c^0\to \Lambda {\eta }^{\prime }$ and search for the decay ${\Xi }_c^0\to \Lambda {\pi }^0$ 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 Belle II detectors, we present a study of the singly Cabibbo-suppressed decays ${\Xi }_c^0\to \Lambda \eta$, $\Lambda {\eta }^{\prime }$, and $\Lambda {\pi }^0$. We observe the decay ${\Xi }_c^0\to \Lambda \eta$ and find evidence for the decay ${\Xi }_c^0\to \Lambda {\eta }^{\prime }$, with 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 $\mathcal{B}({\Xi }_c^0\to \Lambda {\eta }^{\prime })/\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})=(2.48\pm 0.82\pm 0.12)\%$, 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 $\mathcal{B}({\Xi }_c^0\to \Lambda \eta )=(5.95\pm 1.30\pm 0.32\pm 1.13)\times 10^{-4}$, $\mathcal{B}({\Xi }_c^0\to \Lambda {\eta }^{\prime })=(3.55\pm 1.17\pm 0.17\pm 0.68)\times 10^{-4}$, 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 uncertainties arise from the branching fraction of the normalization mode. These results are consistent with most theoretical predictions and further the understanding of the underlying decay mechanisms.

11 pages, 4 figures

References in corpus (16)

• An Introduction to PYTHIA 8.2
• TopoAna: A generic tool for the event type analysis of inclusive Monte-Carlo samples in high energy physics experiments
• Charmed Baryon Physics Circa 2021
• Asymmetries of anti-triplet charmed baryon decays
• Two-body hadronic weak decays of antitriplet charmed baryons
• Track Finding at Belle II
• The Design, Construction, Operation and Performance of the Belle II Silicon Vertex Detector
• Weak Decays of Antitriplet Charmed Baryons from the Perspective of Flavor Symmetry
• Measurements of the branching fractions of ${\Lambda }_c^{+}\to p\eta$ and ${\Lambda }_c^{+}\to p{\pi }^0$ decays at Belle
• Measurement of the integrated luminosity of data samples collected during 2019-2022 by the Belle II experiment
• Punzi-loss: A non-differentiable metric approximation for sensitivity optimisation in the search for new particles
• Measurements of the branching fractions of ${\Xi }_c^0\to \Lambda K_S^0$, ${\Xi }_c^0\to {\Sigma }^0{K}_S^0$, and ${\Xi }_c^0\to {\Sigma }^{+}{K}^{-}$ decays at Belle
• The Imaging Time-of-Propagation Detector at Belle II
• Measurements of the branching fractions of ${\Xi }_c^0\to {\Xi }^0{\pi }^0$, ${\Xi }_c^0\to {\Xi }^0\eta$, and ${\Xi }_c^0\to {\Xi }^0{\eta }^{\prime }$ and asymmetry parameter of ${\Xi }_c^0\to {\Xi }^0{\pi }^0$
• Observations of the singly Cabibbo-suppressed decays ${\Xi }_c^{+}\to p{K}_S^0$, ${\Xi }_c^{+}\to \Lambda {\pi }^{+}$, and ${\Xi }_c^{+}\to {\Sigma }^0{\pi }^{+}$ at Belle and Belle II
• Observation of the doubly Cabibbo-suppressed decay ${\Xi }_c^{+}\to p\varphi$