We present the first observation of the singly Cabibbo-suppressed decay with a significance of and the first evidence of decay with a significance of , based on annihilation data recorded by the BESIII detector at the BEPCII collider. The data correspond to an integrated luminosity of , in the center-of-mass energy range from 4.600 to 4.950 GeV. We determine the branching fractions of and relative to their Cabibbo-favored counterparts to be and , respectively. Moreover, by combining our measured result with the world average of , we obtain the branching fraction . This result significantly departs from theoretical predictions based on quark flavor symmetry, which is underpinned by the presumption of meson pair -wave amplitude dominance.
@article{osti_2290422,
author = {Ablikim, M. and Achasov, M. N. and Adlarson, P. and Ai, X. C. and Aliberti, R. and Amoroso, A. and An, M. R. and An, Q. and Bai, Y. and Bakina, O. and others},
title = {First observation of <math display='inline'> <msubsup> <mi mathvariant='normal'>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> <mo stretchy='false'>→</mo> <mi mathvariant='normal'>Λ</mi> <msup> <mi>K</mi> <mo>+</mo> </msup> <msup> <mi>π</mi> <mn>0</mn> </msup> </math> and evidence of <math display='inline'> <msubsup> <mi mathvariant='normal'>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> <mo stretchy='false'>→</mo> <mi mathvariant='normal'>Λ</mi> <msup> <mi>K</mi> <mo>+</mo> </msup> <msup> <mi>π</mi> <mo>+</mo> </msup> <msup> <mi>π</mi> <mo>−</mo> </msup> </math>},
annote = { We present the first observation of the singly Cabibbo-suppressed decay Λ c + → Λ K + π 0 with a significance of 5.7 σ and the first evidence of Λ c + → Λ K + π + π − decay with a significance of 3.1 σ , based on e + e − annihilation data recorded by the BESIII detector at the BEPCII collider. The data correspond to an integrated luminosity of 6.4 fb − 1 , in the center-of-mass energy range from 4.600 to 4.950 GeV. We determine the branching fractions of Λ c + → Λ K + π 0 and Λ c + → Λ K + π + π − relative to their Cabibbo-favored counterparts to be B ( Λ c + → Λ K + π 0 ) B ( Λ c + → Λ π + π 0 ) = ( 2.09 ± 0.3 9 stat ± 0.0 7 syst ) × 10 − 2 and B ( Λ c + → Λ K + π + π − ) B ( Λ c + → Λ π + π + π − ) = ( 1.13 ± 0.4 1 stat ± 0.0 6 syst ) × 10 − 2 , respectively. Moreover, by combining our measured result with the world average of B ( Λ c + → Λ π + π 0 ) , we obtain the branching fraction B ( Λ c + → Λ K + π 0 ) = ( 1.49 ± 0.2 7 stat ± 0.0 5 syst ± 0.0 8 ref ) × 10 − 3 . This result significantly departs from theoretical predictions based on quark S U ( 3 ) flavor symmetry, which is underpinned by the presumption of meson pair S -wave amplitude dominance. Published by the American Physical Society 2024 },
doi = {10.1103/PhysRevD.109.032003},
url = {https://www.osti.gov/biblio/2290422},
journal = {Physical Review. D.},
issn = {ISSN 2470-0010},
number = {3},
volume = {109},
place = {United States},
publisher = {American Physical Society},
year = {2024},
month = {02}}
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 506, Issue 3https://doi.org/10.1016/S0168-9002(03)01368-8
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 614, Issue 3https://doi.org/10.1016/j.nima.2009.12.050
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 953https://doi.org/10.1016/j.nima.2019.163053