https://doi.org/10.1140/epjc/s10052-020-8078-4
Regular Article - Experimental Physics
Observation of X(2370) and search for X(2120) in 
BESIII Collaboration
1
Institute of High Energy Physics, Beijing, 100049, People’s Republic of China
2
Beihang University, Beijing, 100191, People’s Republic of China
3
Beijing Institute of Petrochemical Technology, Beijing, 102617, People’s Republic of China
4
Bochum Ruhr-University, 44780, Bochum, Germany
5
Carnegie Mellon University, Pittsburgh, PA, 15213, USA
6
Central China Normal University, Wuhan, 430079, People’s Republic of China
7
China Center of Advanced Science and Technology, Beijing, 100190, People’s Republic of China
8
COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore, 54000, Pakistan
9
Fudan University, Shanghai, 200443, People’s Republic of China
10
G.I. Budker Institute of Nuclear Physics SB RAS (BINP), Novosibirsk, 630090, Russia
11
GSI Helmholtzcentre for Heavy Ion Research GmbH, 64291, Darmstadt, Germany
12
Guangxi Normal University, Guilin, 541004, People’s Republic of China
13
Guangxi University, Nanning, 530004, People’s Republic of China
14
Hangzhou Normal University, Hangzhou, 310036, People’s Republic of China
15
Helmholtz Institute Mainz, Johann-Joachim-Becher-Weg 45, 55099, Mainz, Germany
16
Henan Normal University, Xinxiang, 453007, People’s Republic of China
17
Henan University of Science and Technology, Luoyang, 471003, People’s Republic of China
18
Huangshan College, Huangshan, 245000, People’s Republic of China
19
Hunan Normal University, Changsha, 410081, People’s Republic of China
20
Hunan University, Changsha, 410082, People’s Republic of China
21
Indian Institute of Technology Madras, Chennai, 600036, India
22
Indiana University, Bloomington, IN, 47405, USA
23
INFN Laboratori Nazionali di Frascati, 00044, Frascati, Italy
24
INFN and University of Perugia, 06100, Perugia, Italy
25
INFN Sezione di Ferrara, 44122, Ferrara, Italy
26
University of Ferrara, 44122, Ferrara, Italy
27
Institute of Physics and Technology, Peace Ave. 54B, Ulaanbaatar, 13330, Mongolia
28
Johannes Gutenberg University of Mainz, Johann-Joachim-Becher-Weg 45, 55099, Mainz, Germany
29
Joint Institute for Nuclear Research, Dubna, Moscow Region, 141980, Russia
30
II. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392, Giessen, Germany
31
KVI-CART, University of Groningen, 9747 AA, Groningen, The Netherlands
32
Lanzhou University, Lanzhou, 730000, People’s Republic of China
33
Liaoning University, Shenyang, 110036, People’s Republic of China
34
Nanjing Normal University, Nanjing, 210023, People’s Republic of China
35
Nanjing University, Nanjing, 210093, People’s Republic of China
36
Nankai University, Tianjin, 300071, People’s Republic of China
37
Peking University, Beijing, 100871, People’s Republic of China
38
Shandong Normal University, Jinan, 250014, People’s Republic of China
39
Shandong University, Jinan, 250100, People’s Republic of China
40
Shanghai Jiao Tong University, Shanghai, 200240, People’s Republic of China
41
Shanxi University, Taiyuan, 030006, People’s Republic of China
42
Sichuan University, Chengdu, 610064, People’s Republic of China
43
Soochow University, Suzhou, 215006, People’s Republic of China
44
Southeast University, Nanjing, 211100, People’s Republic of China
45
State Key Laboratory of Particle Detection and Electronics, Beijing, 100049, People’s Republic of China
46
State Key Laboratory of Particle Detection and Electronics, Hefei, 230026, People’s Republic of China
47
Sun Yat-Sen University, Guangzhou, 510275, People’s Republic of China
48
Tsinghua University, Beijing, 100084, People’s Republic of China
49
Ankara University, 06100, Tandogan, Ankara, Turkey
50
Istanbul Bilgi University, 34060, Eyup, Istanbul, Turkey
51
Uludag University, 16059, Bursa, Turkey
52
Near East University, Mersin 10, Nicosia, North Cyprus, Turkey
53
University of Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China
54
University of Hawaii, Honolulu, HI, 96822, USA
55
University of Jinan, Jinan, 250022, People’s Republic of China
56
University of Manchester, Oxford Road, Manchester, M13 9PL, UK
57
University of Minnesota, Minneapolis, MN, 55455, USA
58
University of Muenster, Wilhelm-Klemm-Str. 9, 48149, Munster, Germany
59
University of Oxford, Keble Rd, Oxford, OX13RH, UK
60
University of Science and Technology Liaoning, Anshan, 114051, People’s Republic of China
61
University of Science and Technology of China, Hefei, 230026, People’s Republic of China
62
University of South China, Hengyang, 421001, People’s Republic of China
63
University of the Punjab, Lahore, 54590, Pakistan
64
University of Turin, 10125, Turin, Italy
65
University of Eastern Piedmont, 15121, Alessandria, Italy
66
INFN, 10125, Turin, Italy
67
Uppsala University, Box 516, 75120, Uppsala, Sweden
68
Wuhan University, Wuhan, 430072, People’s Republic of China
69
Xinyang Normal University, Xinyang, 464000, People’s Republic of China
70
Zhejiang University, Hangzhou, 310027, People’s Republic of China
71
Zhengzhou University, Zhengzhou, 450001, People’s Republic of China
* e-mail: gongli@ihep.ac.cn
Received:
25
December
2019
Accepted:
23
May
2020
Published online:
17
August
2020
Using a sample of 
events collected with the BESIII detector, we perform a study of 
. X(2370) is observed in the 
invariant-mass distribution with a statistical significance of 
. Its resonance parameters are measured to be 
and 
. The product branching fractions for 
and 
are determined to be 
and 
, respectively. No evident signal for X(2120) is observed in the invariant-mass distribution. The upper limits for the product branching fractions of 
and 
are determined to be 
and 
at the 90% confidence level, respectively.
© The Author(s), 2020
