First Observation of the Direct Production of the χc1 in e+e- Annihilation

(BESIII Collaboration)

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We study the direct production of the JPC=1++ charmonium state χc1(1P) in electron-positron annihilation by carrying out an energy scan around the mass of the χc1(1P). The data were collected with the BESIII detector at the BEPCII collider. An interference pattern between the signal process e+e-→χc1(1P)→γJ/ψ→γμ+μ- and the background processes e+e-→γISRJ/ψ→γISRμ+μ- and e+e-→γISRμ+μ- is observed by combining all the data samples. The χc1(1P) signal is observed with a significance of 5.1σ. This is the first observation of a C-even state directly produced in e+e- annihilation. The electronic width of the χc1(1P) resonance is determined to be Γee=(0.12-0.08+0.13) eV, which is of the same order of magnitude as theoretical calculations.

Original languageEnglish (US)
Article number122001
JournalPhysical review letters
Issue number12
StatePublished - Sep 16 2022

Bibliographical note

Funding Information:
The BESIII Collaboration thanks the staff of BEPCII and the IHEP computing center for their strong support. We acknowledge the continuous theory support for this analysis by Henryk Czyż and Hans Kühn. This work is supported in part by National Key R&D Program of China under Contracts No. 2020YFA0406300, No. 2020YFA0406400; National Natural Science Foundation of China (NSFC) under Contracts No. 11635010, No. 11735014, No. 11835012, No. 11935015, No. 11935016, No. 11935018, No. 11961141012, No. 12022510, No. 12025502, No. 12035009, No. 12035013, No. 12192260, No. 12192261, No. 12192262, No. 12192263, No. 12192264, No. 12192265; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No. U1832207, No. U2032108; CAS Key Research Program of Frontier Sciences under Contract No. QYZDJ-SSW-SLH040; 100 Talents Program of CAS; Shanghai Pujiang Program (20PJ1401700); INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology; ERC under Contract No. 758462; European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement under Contract No. 894790; German Research Foundation DFG under Contracts No. 443159800, No. 455635585, Collaborative Research Center CRC 1044, GRK 2149, Research Unit FOR5327; Istituto Nazionale di Fisica Nucleare, Italy; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Science and Technology fund; STFC (United Kingdom); The Royal Society, UK under Contracts No. DH140054, No. DH160214; The Swedish Research Council; U.S. Department of Energy under Contract No. DE-FG02-05ER41374.

Publisher Copyright:
© 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the ""Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.


Dive into the research topics of 'First Observation of the Direct Production of the χc1 in e+e- Annihilation'. Together they form a unique fingerprint.

Cite this