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arXiv · 1906.07942

Visible narrow cusp structure in $Λ_c^+\to p K^- π^+$ enhanced by triangle singularity

Xiao-Hai Liu·Gang Li·Ju-Jun Xie·Qiang Zhao
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Abstract

A resonance-like structure as narrow as 10 MeV is observed in the $K^-p$ invariant mass distributions in $Λ_c^+\to p K^- π^+$ at Belle. Based on the large data sample of about 1.5 million events and the small bin width of just 1 MeV for the $K^-p$ invariant mass spectrum, the narrow peak is found precisely lying at the $Λη$ threshold. While lacking evidence for a quark model state with such a narrow width at this mass region, we find that this narrow structure can be naturally identified as a threshold cusp but enhanced by the nearby triangle singularity via the $Λ$-$a_0(980)^+$ or $η$-$Σ(1660)^+$ rescatterings.

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Xiao-Hai Liu, Gang Li, Ju-Jun Xie, Qiang Zhao. 2019-06-20. Visible narrow cusp structure in $Λ_c^+\to p K^- π^+$ enhanced by triangle singularity. https://doi.org/10.1103/physrevd.100.054006

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