Measurements of the branching fractions of Ξ_c⁺→ Σ⁺K_S⁰, Ξ_c⁺→ Ξ⁰π⁺, and Ξ_c⁺→ Ξ⁰K⁺ at Belle and Belle II

2025/03/22 by Belle, Collaborations, Belle II, : +357
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2503.17643

Abstract

Using 983.0 \rmfb^-1 and 427.9 \rmfb^-1 data samples collected with the Belle and Belle II detectors at the KEKB and SuperKEKB asymmetric energy e⁺e^- colliders, respectively, we present studies of the Cabibbo-favored Ξ_c⁺ decays Ξ_c⁺→ Σ⁺K_S⁰ and Ξ_c⁺→ Ξ⁰π⁺, and the singly Cabibbo-suppressed decay Ξ_c⁺→ Ξ⁰K⁺. The ratios of branching fractions of Ξ_c⁺→ Σ⁺K_S⁰ and Ξ_c⁺→ Ξ⁰K⁺ relative to that of Ξ_c⁺→Ξ^-π⁺π⁺ are measured for the first time, while the ratio \cal B(Ξ_c⁺→Ξ⁰π⁺)/\cal B(Ξ_c⁺→Ξ^-π⁺π⁺) is also determined and improved by an order of magnitude in precision. The measured branching fraction ratios are \frac\calB(Ξ_c⁺ → Σ⁺K_S⁰)\calB(Ξ_c⁺→ Ξ^-π⁺π⁺)= 0.067 ± 0.007 ± 0.003, \frac\calB(Ξ_c⁺ → Ξ⁰π⁺)\calB(Ξ_c⁺→ Ξ^-π⁺π⁺) = 0.251 ± 0.005 ± 0.010, \frac\calB(Ξ_c⁺ → Ξ⁰K⁺)\calB(Ξ_c⁺→ Ξ^-π⁺π⁺) = 0.017 ± 0.003 ± 0.001. Additionally, the ratio \cal B(Ξ_c⁺→Ξ⁰K⁺)/\cal B(Ξ_c⁺→Ξ⁰π⁺) is measured to be 0.068 ± 0.010 ± 0.004. Here, the first and second uncertainties are statistical and systematic, respectively. Multiplying the ratios by the branching fraction of the normalization mode, \mathcal B(Ξ_c⁺→Ξ^-π⁺π⁺)= (2.9± 1.3)%, we obtain the following absolute branching fractions \cal B(Ξ_c⁺→Σ⁺K⁰_S) = (0.194 ± 0.021 ± 0.009 ± 0.087 )%, \cal B(Ξ_c⁺→Ξ⁰π⁺) = (0.728 ± 0.014 ± 0.027 ± 0.326 )%, \cal B(Ξ_c⁺→Ξ⁰K⁺) = (0.049 ± 0.007 ± 0.003 ± 0.022 )%.

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