6533b82cfe1ef96bd128f39f

RESEARCH PRODUCT

Search for the Σ⁎ state in Λc+→π+π0π−Σ+ decay by triangle singularity

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Abstract A Σ ⁎ resonance with spin-parity J P = 1 / 2 − and mass in the vicinity of the K ¯ N threshold has been predicted in the unitary chiral approach and inferred from the analysis of CLAS data on the γ p → K + π 0 Σ 0 reaction. In this work, based on the dominant Cabibbo favored weak decay mechanism, we perform a study of Λ c + → π + π 0 Σ ⁎ with the possible Σ ⁎ state decaying into π − Σ + through a triangle diagram. This process is initiated by Λ c + → π + K ¯ ⁎ N , then the K ¯ ⁎ decays into K ¯ π and K ¯ N produce the Σ ⁎ through a triangle loop containing K ¯ ⁎ N K ¯ which develops a triangle singularity. We show that the π − Σ + state is generated from final state interaction of K ¯ N in S-wave and isospin I = 1 , and the Λ c + → π + π 0 π − Σ + decay can be used to study the possible Σ ⁎ state around the K ¯ N threshold. The proposed decay mechanism can provide valuable information on the nature of the Σ ⁎ resonance and can in principle be tested by facilities such as LHCb, BelleII and BESIII.