# Effective-Range-Expansion Study of Near Threshold Heavy-Flavor Resonances

Guo, Zhi-Hui  (Department of Physics and Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050024, China) ; Gao, Rui (Department of Physics and Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050024, China) ; Kang, Xian-Wei (College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China) ; Oller, J. A. (Departamento de Física, Universidad de Murcia, E-30071 Murcia, Spain)

18 June 2019

Abstract: In this work, we study the resonances near the thresholds of the open heavy-flavor hadrons using the effective-range-expansion method. The unitarity, analyticity, and compositeness coefficient are also taken into account in our theoretical formalism. We consider the ${Z}_{c}\left(\mathrm{3900}\right)$ , $X\left(\mathrm{4020}\right)$ , ${\chi }_{c\mathrm{1}}\left(\mathrm{4140}\right)$ , $\psi \left(\mathrm{4260}\right)$ , and $\psi \left(\mathrm{4660}\right)$ . The scattering lengths and effective ranges from the relevant elastic $S$ -wave scattering amplitudes are determined. Tentative discussions on the inner structures of the aforementioned resonances are given.

Published in: Advances in High Energy Physics 2019 (2019) 4651908