https://doi.org/10.1140/epjp/s13360-023-04181-0
Regular Article
Charmonium mass shifts in an unquenched quark model
1
College of Science, Jinling Institute of Technology, 211169, Nanjing, People’s Republic of China
2
Department of Physics, Yancheng Institute of Technology, 224000, Yancheng, People’s Republic of China
3
College of Science, Guizhou University of Engineering Science, 551700, Bijie, People’s Republic of China
Received:
12
April
2023
Accepted:
9
June
2023
Published online:
26
July
2023
In this paper, we performed a coupled-channel calculation and evaluated the mass shifts for all 1S, 2S, 1P, 2P and 1D charmonium valence states below 4 GeV, by incorporating the four-quark components (D, 
, 
and 
meson pairs) into the quark model. The valence-continuum coupling is provided by the 
quark-pair creation model. The induced mass shifts appear to be large and negative with the original transition operator in model, which raised up challenges for the valence quark model. More QCD-motivated models should be employed for the quark-pair creation Hamiltonian. So herein, we recalculated the mass shifts with the improved transition operator introduced in our previous work and the mass shifts are reduced by 
averagely. Besides, as a exercise, we adjust the confinement parameter 
and recalculate the spectrum of the charmonium states. The masses of some charmonium states are reproduced well.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
