<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mn>0</mml:mn><mml:mo>+</mml:mo></mml:msup></mml:math> fully-charmed tetraquark states
Jian-Rong Zhang
Abstract
Motivated by the LHCb's new observation of structures in the $J/\ensuremath{\psi}$-pair invariant mass spectrum, which could be classified as possible $cc\overline{c}\overline{c}$ tetraquark candidates, we systematically study ${0}^{+}$ fully-charmed tetraquark states through QCD sum rules. Developing the calculation techniques to fourfold heavy hadronic systems, four different configuration currents with ${0}^{+}$ are considered, and vacuum condensates up to dimension six are included in the operator product expansion. Finally, the mass values acquired for ${0}^{+}\text{ }\text{ }cc\overline{c}\overline{c}$ tetraquark states agree well with the experimental data of the broad structure, which support that it could be a ${0}^{+}$ fully-charmed tetraquark state.