Measurements of the branching fractions of Λ_c⁺→ΛK⁺ π⁰ and Λ_c⁺→ΛK⁺ η decays at Belle and Belle II

@misc{belle2026measurements,
  title = {{Measurements of the branching fractions of $Λ_c^+\toΛK^+ π^0$ and $Λ_c^+\toΛK^+ η$ decays at Belle and Belle II}},
  author = {Belle and Belle II Collaborations and M. Abumusabh and I. Adachi and A. Aggarwal and Y. Ahn and H. Aihara and M. Akdag and N. Akopov and A. Akram and S. Alghamdi and M. Alhakami and A. Aloisio and N. Althubiti and K. Amos and M. Angelsmark and N. Anh Ky and K. Arai and H. Atmacan and T. Aushev and V. Aushev and R. Ayad and V. Babu and N. K. Baghel and S. Bahinipati and P. Bambade and Sw. Banerjee and M. Barrett and M. Bartl and J. Baudot and A. Beaubien and F. Becherer and J. Becker and G. F. Benfratello and J. V. Bennett and V. Bertacchi and M. Bertemes and E. Bertholet and M. Bessner and S. Bettarini and P. Bhagawath Prasad and V. Bhardwaj and B. Bhuyan and F. Bianchi and T. Bilka and A. Biswas and A. Bobrov and A. Bondar and G. Bonvicini and A. Boschetti and A. Bozek and M. Bračko and P. Branchini and N. Brenny and R. A. Briere and T. E. Browder and A. Budano and F. Callet and Q. Campagna and M. Campajola},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.31377},
  eprint = {2610.31377},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.31377},
}

TY  - UNPB
TI  - Measurements of the branching fractions of Λ_c^+→ΛK^+ π^0 and Λ_c^+→ΛK^+ η decays at Belle and Belle II
AU  - Belle
AU  - Belle II Collaborations
AU  - M. Abumusabh
AU  - I. Adachi
AU  - A. Aggarwal
AU  - Y. Ahn
AU  - H. Aihara
AU  - M. Akdag
AU  - N. Akopov
AU  - A. Akram
AU  - S. Alghamdi
AU  - M. Alhakami
AU  - A. Aloisio
AU  - N. Althubiti
AU  - K. Amos
AU  - M. Angelsmark
AU  - N. Anh Ky
AU  - K. Arai
AU  - H. Atmacan
AU  - T. Aushev
AU  - V. Aushev
AU  - R. Ayad
AU  - V. Babu
AU  - N. K. Baghel
AU  - S. Bahinipati
AU  - P. Bambade
AU  - Sw. Banerjee
AU  - M. Barrett
AU  - M. Bartl
AU  - J. Baudot
AU  - A. Beaubien
AU  - F. Becherer
AU  - J. Becker
AU  - G. F. Benfratello
AU  - J. V. Bennett
AU  - V. Bertacchi
AU  - M. Bertemes
AU  - E. Bertholet
AU  - M. Bessner
AU  - S. Bettarini
AU  - P. Bhagawath Prasad
AU  - V. Bhardwaj
AU  - B. Bhuyan
AU  - F. Bianchi
AU  - T. Bilka
AU  - A. Biswas
AU  - A. Bobrov
AU  - A. Bondar
AU  - G. Bonvicini
AU  - A. Boschetti
AU  - A. Bozek
AU  - M. Bračko
AU  - P. Branchini
AU  - N. Brenny
AU  - R. A. Briere
AU  - T. E. Browder
AU  - A. Budano
AU  - F. Callet
AU  - Q. Campagna
AU  - M. Campajola
PY  - 2026
DA  - 2026/10/22
PB  - arXiv
DO  - 10.48550/arxiv.2610.31377
UR  - https://arxiv.org/abs/2610.31377
AB  - We present a study of the three-body, singly Cabibbo-suppressed decays Λ_c^+ → ΛK^+ π^0 and Λ_c^+ → ΛK^+ η using data recorded with the Belle and Belle II detectors at the KEKB and SuperKEKB e^+ e^- colliders. The data samples correspond to integrated luminosities of 980fb^−1 and 570fb^−1, respectively. We measure their branching-fraction ratios relative to the Cabibbo-favored decay Λ_c^+ → Λπ^+ π^0 as ℬ(Λ_c^+ → ΛK^+ π^0)/ℬ(Λ_c^+ → Λπ^+ π^0)=(1.82 ± 0.07 ± 0.07)%, with significantly improved precision compared to the previous measurement, and ℬ(Λ_c^+ → ΛK^+ η)/ℬ(Λ_c^+ → Λπ^+ π^0)=(8.73 ± 0.35 ± 0.43)×10^−3, corresponding to the first observation of the Λ_c^+ → ΛK^+ η decay with a statistical significance exceeding 10 standard deviations. The first and second uncertainties are statistical and systematic, respectively. Using the world-average value of the branching fraction for Λ_c^+ → Λπ^+ π^0, we obtain the branching fractions ℬ(Λ_c^+ → ΛK^+ π^0)=(1.29± 0.05± 0.05± 0.06)×10^−3 and ℬ(Λ_c^+ → ΛK^+ η)=(6.20± 0.25± 0.31± 0.30)×10^−4, where the third uncertainty arises from the uncertainty in the world-average value of ℬ(Λ_c^+ → Λπ^+ π^0). The measured ℬ(Λ_c^+→ΛK^+η) is significantly larger than predictions based on SU(3) flavor symmetry.
ER  -