https://doi.org/10.1140/epjc/s10052-019-6755-y
Regular Article - Theoretical Physics
QCD sum rule studies of 
tetraquark states with 
1
School of Physics, Beihang University, Beijing, 100191, China
2
School of Physics, Sun Yat-Sen University, Guangzhou, 510275, China
3
Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) and Institute of Modern Physics, Fudan University, Shanghai, 200433, China
* e-mail: hxchen@buaa.edu.cn
Received:
1
February
2019
Accepted:
4
March
2019
Published online:
13
March
2019
We apply the method of QCD sum rules to study the structure X newly observed by the BESIII Collaboration in the 
mass spectrum in 2.0–2.1 GeV region in the 
decay. We construct all the tetraquark currents with , and use them to perform QCD sum rule analyses. One current leads to reliable QCD sum rule results and the mass is extracted to be 
GeV, suggesting that the structure X can be interpreted as an tetraquark state with . The Y(2175) can be interpreted as its partner having 
, and we propose to search for the other two partners, the tetraquark states with 
and 
, in the 
, 
, and 
mass spectra.
© The Author(s), 2019
