Revisiting the $Λ_c^+ \to nπ^+η$ decay in light of the BESIII measurement

Abstract

Motivated by the latest BESIII measurements on $Λ_c^+\to nπ^+η$, we perform a systematic theoretical study of this decay. We take into account contributions from the $N(1535)$ state dynamically generated by $S$-wave pseudoscalar meson-octet baryon interactions, the $a_0(980)$ resonance originating from the $S$-wave pseudoscalar meson-pseudoscalar meson interactions, together with the intermediate states $N(1440)$ and $a_2(1320)$. Our results indicate that $a_0(980)$ provides a significant contribution to this process. The inclusion of $a_2(1320)$ hardly improves the fitting quality, while the nucleon resonances play a crucial role in describing the experimental behavior of the $π^+η$ invariant mass spectrum in both low and high energy regions. Restricted by insufficient experimental statistics and a coarse bin size of 33 MeV, the precise contribution fraction of $a_0(980)$ cannot be reliably extracted. We propose future higher-precision and higher-statistics experimental measurements of $Λ_c^+\to nπ^+η$, which can help reveal the intrinsic nature of $a_0(980)$ and quantify the roles of different excited nucleon states in this decay.