Abstract
We report branching fraction measurements of four decay modes of the Λc+ baryon, each of which includes an η meson and a Λ baryon in the final state, and all of which are measured relative to the Λc+→pK−π+ decay mode. The results are based on a 980 fb−1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e− collider. Two decays, Λc+→ηΣ0π+ and Λ(1670)π+, are observed for the first time, while the measurements of the other decay modes, Λc+→ηΛπ+ and ηΣ(1385)+, are more precise than those made previously. We obtain relative branching fractions of B(Λc+→ηΛπ+)/B(Λc+→pK−π+)=0.293±0.003±0.014, B(Λc+→ηΣ0π+)/B(Λc+→pK−π+)=0.120±0.006±0.010, B(Λc+→Λ(1670)π+)×B(Λ(1670)→ηΛ)/B(Λc+→pK−π+)=(5.54±0.29±0.73)×10−2, and B(Λc+→ηΣ(1385)+)/B(Λc+→pK−π+)=0.192±0.006±0.016. The mass and width of the Λ(1670) are also precisely determined to be 1674.3±0.8±4.9 MeV/c2 and 36.1±2.4±4.8 MeV, respectively, where the uncertainties are statistical and systematic, respectively.Received 26 August 2020Accepted 28 January 2021DOI:https://doi.org/10.1103/PhysRevD.103.052005Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionHadronic decaysPhysical SystemsCharmed baryonsHyperonsPropertiesMassTechniquesLepton collidersParticle decaysPrecision measurementsParticles & Fields
Highlights
The branching fractions of weakly decaying charmed baryons provide a way to study both strong and weak interactions
We report branching fraction measurements of four decay modes of the Λþc baryon, each of which includes an η meson and a Λ baryon in the final state, and all of which are measured relative to the Λþc → pK−πþ decay mode
Branching fraction measurements of new decay modes of the Λþc or known decay modes with higher precision are crucial
Summary
The branching fractions of weakly decaying charmed baryons provide a way to study both strong and weak interactions. Relative to the Λþc → pK−πþ mode to be converted to absolute branching fraction measurements with high precision [5]. We present measurements of branching fractions for the four decay modes, Λþc → ηΛπþ, Λþc → ηΣ0πþ, Λþc → Λð1670Þπþ, and Λþc → ηΣð1385Þþ, all measured relative to the Λþc → pK−πþ decay mode. The Λþc → Λð1670Þπþ and Λþc → ηΣð1385Þþ decay modes are studied as resonant structures in the Λþc → ηΛπþ decay, while the Λþc → ηΣ0πþ decay is observed indirectly as a feed-down to the invariant mass of ηΛπþ, MðηΛπþÞ, spectrum. While BðΛþc → ηΛπþÞ and BðΛþc → ηΣð1385ÞþÞ have previously been measured by CLEO [11] and by BESIII [12], we report the first observation of the Λþc → ηΣ0πþ and Λþc → Λð1670Þπþ decay modes and their branching fractions. We make precise measurements of the masses and widths of the Λð1670Þ and Σð1385Þþ
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