https://doi.org/10.1140/epjc/s10052-020-8008-5
Regular Article - Theoretical Physics
Pole analysis on the hadron spectroscopy of 
1
School of Physics and Electronics, Hunan University, Changsha, 410082, China
2
College of Nuclear Science and Technology, Beijing Normal University, Beijing, 100875, China
* e-mail: dailingyun@hnu.edu.cn
Received:
19
March
2020
Accepted:
1
May
2020
Published online:
18
May
2020
In this paper we study the 
spectroscopy in the process of . The final state interactions of coupled channel –
–
are constructed based on K-matrix with the Chew–Mandelstam function. We build the amplitude according to the Au–Morgan–Pennington method. The event shape is fitted and the decay width of is used to constrain the parameters, too. With the amplitudes we extract out the poles and their residues. Our amplitude and pole analysis suggest that the 
should be 
molecule, the 
could be an S-wave compact pentaquark state, and the structure around 
is caused by the cusp effect. The future experimental measurement of the decays of 
and 
would further help to study the nature of these resonances.
© The Author(s), 2020
