Speaker
Xiao-Hai Liu
(Tianjin University)
Description
A resonance-like structure as narrow as 10 MeV is observed in the $K^-p$ invariant mass distributions in $\Lambda_c^+\to p K^- \pi^+$. This precise measurement is based on a data sample of about 1.5 million events, and the bin width of $K^-p$ invariant mass is only 1 MeV. The narrow peak precisely lies on the $\Lambda\eta$ threshold, because of which it is natural to identify it as a threshold cusp. Being different from the common two-body unitary cusp, we find that the narrowness of this cusp can be induced by a nearby triangle singularity of the $\Lambda$-$a_0^+(980)$ or $\eta$-$\Sigma(1660)$ rescattering process.
Primary author
Xiao-Hai Liu
(Tianjin University)
Co-authors
Gang Li
(Qufu Normal University)
Dr
Ju-Jun Xie
(IMP@CAS)
Prof.
Qiang ZHAO
(Institute of High Energy Physics, Chinese Academy of Sciences)
