| 要約: | Abstract We develop the formalism for production of a fully heavy tetraquark and apply it to the calculation of pp → T 4c + X cross-sections. We demonstrate that the production cross-section of a fully heavy tetraquark, even if it is a diquark-antidiquark cluster, can be obtained in the meson-like basis, for which the spin-color projection technique is well established. Prompted by the recent LHCb, ATLAS and CMS data, we perform a pQCD calculation of O $$ \mathcal{O} $$ ( α s 5 $$ {\alpha}_s^5 $$ ) short-distance factors in the dominant channel of gluon fusion, and match these to the four-body T 4c wave functions in order to obtain the unpolarized T 4c (0++ , 1+− , 2++) cross-sections. The novelty in comparison with the recently published article [1] lies in the fact that we predict the absolute values as well as the dσ/dp T spectra in the kinematic ranges accessible at the ongoing LHC experiments. From the comparison with the signal yield at LHCb we derive the constraints on the Φ · Br(J/ψ J/ψ) (reduced wave function times branching) product for the T 4c candidates for X(6900) and observe that X(6900) is compatible with a 2++(2S) state.
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