Search for the Σ(1380)1/2^- state in Λ⁺_c → γπ⁺ Λ decay by triangle singularity

2024/08/23 by K. Wang, Yufei Wang, Wang, Ke +5
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear Theory (nucl-th) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions

paper · pdf · doi:10.48550/arxiv.2408.12965

openalex publication_date 2024/08/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

In this work, we investigate the resonance production in Λ⁺_c → γπ⁺ Λ decay through the triangle singularity (TS) mechanism, within an effective Lagrangian approach. We find that the appropriate loop decay process could develop a triangle singularity in the invariant mass M_πΛ around 1.35 GeV, with the shape depending on the quantum numbers of Σ^* states that couple to the final πΛ system. Especially, the Σ(1380)1/2^- state newly predicted in the pentaquark model, if exists, significantly enhances the TS contribution and sharpens the TS peak due to the S-wave Σ^*πΣ vertex in the loop. Therefore, the existence of the Σ(1380)1/2^- state can be examined by measuring the TS signal in Λ⁺_c → γπ⁺ Λ. Considering also possible tree-level diagrams, we additionally obtain the branching ratio \rm Br(Λ⁺_c → γπ⁺ Λ)≃ 1.5× 10^-5. We suggest the investigation of this reaction by future BESIII, LHCb, and Belle experiments.

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