Observation of the Singly Cabibbo Suppressed Decay Λ_{c}^{+}→nπ^{+}

BESIII Collaboration

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The singly Cabibbo-suppressed decay Λ_{c}^{+}→nπ^{+} is observed for the first time with a statistical significance of 7.3σ by using 3.9  fb^{-1} of e^{+}e^{-} collision data collected at center-of-mass energies between 4.612 and 4.699 GeV with the BESIII detector at BEPCII. The branching fraction of Λ_{c}^{+}→nπ^{+} is measured to be (6.6±1.2_{stat}±0.4_{syst})×10^{-4}. By taking the upper limit of branching fractions of Λ_{c}^{+}→pπ^{0} from the Belle experiment, the ratio of branching fractions between Λ_{c}^{+}→nπ^{+} and Λ_{c}^{+}→pπ^{0} is calculated to be larger than 7.2 at the 90% confidence level, which disagrees with most predictions of the available phenomenological models. In addition, the branching fractions of the Cabibbo-favored decays Λ_{c}^{+}→Λπ^{+} and Λ_{c}^{+}→Σ^{0}π^{+} are measured to be (1.31±0.08_{stat}±0.05_{syst})×10^{-2} and (1.22±0.08_{stat}±0.07_{syst})×10^{-2}, respectively, which are consistent with previous results.

Original languageEnglish (US)
Article number142001
JournalPhysical review letters
Issue number14
StatePublished - Apr 8 2022

Bibliographical note

Funding Information:
The BESIII Collaboration thanks the staff of BEPCII, the IHEP computing center, and the supercomputing center of the University of Science and Technology of China (USTC) for their strong support. The authors are grateful to Hai-Yang Cheng, Fanrong Xu, and Xianwei Kang for enlightening discussions. This work is supported in part by National Key R&D Program of China under Contracts No. 2020YFA0406400, No. 2020YFA0406300; National Natural Science Foundation of China (NSFC) under Contracts No. 11335008, No. 11625523, No. 11635010, No. 11735014, No. 11822506, No. 11835012, No. 11935015, No. 11935016, No. 11935018, No. 11961141012, No. 12022510, No. 12025502, No. 12035009, No. 12035013, No. 12061131003, No. 12005311, No. 11805086, No. 11705192, and No. 11950410506; the Fundamental Research Funds for the Central Universities, University of Science and Technology of China, Sun Yat-sen University, Lanzhou University, University of Chinese Academy of Sciences; 100 Talents Program of Sun Yat-sen University; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No. U1732263, No. U1832207, No. U1832103, No. U2032111; CAS Key Research Program of Frontier Sciences under Contract No. QYZDJ-SSW-SLH040; 100 Talents Program of CAS; China Postdoctoral Science Foundation under Contracts No. 2019M662152, No. 2020T130636; INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology; ERC under Contract No. 758462; European Union Horizon 2020 research and innovation programme under Marie Skłodowska-Curie Grant Agreement No. 894790; German Research Foundation DFG under Contracts No. 443159800, Collaborative Research Center CRC 1044, FOR 2359, FOR 2359, GRK 214; Istituto Nazionale di Fisica Nucleare, Italy; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Science and Technology fund; Olle Engkvist Foundation under Contract No. 200-0605; STFC (U.K.); The Knut and Alice Wallenberg Foundation (Sweden) under Contract No. 2016.0157; The Royal Society, U.K. under Contracts No. DH140054, No. DH160214; The Swedish Research Council; U.S. Department of Energy under Contracts No. DE-FG02-05ER41374, No. DE-SC-0012069.

Publisher Copyright:
© 2022 authors. Published by the American Physical Society.


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