Nature of X(6900) and its production mechanism at LHCb

We show that the Pomeron exchanges play a unique role in vector charmonium scatterings. Such a mechanism can provide a natural explanation for the nontrivial structures in the di-J/psi spectrum observed by the LHCb Collaboration. The narrow structure X(6900), as a dynamically generated resonance pole, can arise from the Pomeron exchanges and coupled-channel effects between the J/psi-J/psi, J/psi-psi(2S) scatterings. A pole structure near the di-J/psi threshold is also found. Meanwhile, we predict that X(6900) can produce significant threshold enhancement in the J/psi-psi(2S) energy spectrum which can be searched for at LHCb. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

We find that Pomeron exchanges play a crucial role in vector charmonium scatterings and can provide an explanation for the unique structures observed by the LHCb Collaboration. The presence of a narrow structure X(6900), formed by the exchange of Pomerons and coupled-channel effects, is predicted near the di-J/psi threshold. Furthermore, we predict that X(6900) will result in significant threshold enhancement in the J/psi-psi(2S) energy spectrum, which can be detected at LHCb.