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Role of $Σ^{*} (1 / 2^{-})$ baryons in $Λ_{c} \to Λ π^{+} π^{+} π^{-}$ decay

School of Physics and Technology, Nanjing Normal University, Nanjing 210097, China

^*Contact author: junhe@njnu.edu.cn

Phys. Rev. C 112, 015205 – Published 10 July, 2025

DOI: https://doi.org/10.1103/g7md-pt2c

Abstract

Based on Belle data, the structure around 1435 MeV and the role of the $Σ (1380)$ resonance in the decay process $Λ_{c} \to Λ π^{-} π^{+} π^{+}$ are investigated. The $Λ π^{\pm}$ invariant mass spectra are approximately reproduced by the contribution from the $Σ (1385)$ , modeled as a Breit-Wigner resonance combined with background. However, an additional contribution is required to account for the pronounced enhancement near 1435 MeV. To describe this structure, two scenarios are considered for the $Σ (1435)$ : one as a Breit-Wigner resonance with spin-parity $1 / 2^{-}$ described via effective Lagrangians, and the other as a rescattering effect arising from coupled-channel interactions. Specifically, the channels ${\bar{K}}^{0} p$ , $π^{0} Σ^{+}$ , $π^{+} Σ^{0}$ , $π^{+} Λ$ , and $η Σ^{+}$ are included for the positively charged mode, and $K^{-} n$ , $π^{0} Σ^{-}$ , $π^{-} Σ^{0}$ , $π^{-} Λ$ , and $η Σ^{-}$ for the negatively charged mode. The rescattering contributions are evaluated using the quasipotential Bethe-Salpeter equation approach. Simulated invariant mass spectra are generated and fitted to the experimental data. Both the Breit-Wigner and rescattering mechanisms provide reasonable descriptions of the enhancement near 1435 MeV. The rescattering approach naturally generates a cusp-like structure near threshold, which closely resembles the feature observed in the data. Furthermore, the inclusion of the $Σ (1380)$ resonance with spin-parity $1 / 2^{-}$ significantly improves the fit in the low-energy region and further enhances the description near 1435 MeV through interference effects. These results underscore the essential roles of the two $Σ^{*} (1 / 2^{-})$ states in accurately describing the invariant mass distributions in the decay $Λ_{c} \to Λ π^{+} π^{+} π^{-}$ .

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Phys. Rev. C 112, 015205– Published 10 July, 2025

Vol. 112, Iss. 1 — July 2025

Received 8 May 2025
Accepted 9 June 2025

DOI: https://doi.org/10.1103/g7md-pt2c

Published 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.

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Role of $Σ^{*} (1 / 2^{-})$ baryons in $Λ_{c} \to Λ π^{+} π^{+} π^{-}$ decay

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Role of Σ*(1/2−) baryons in Λc→Λπ+π+π− decay

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Role of $Σ^{*} (1 / 2^{-})$ baryons in $Λ_{c} \to Λ π^{+} π^{+} π^{-}$ decay