Fully heavy tetraquark states and their evidences in LHC observations

Abstract

Stimulated by the exciting progress on the observations of the fully charmed tetraquarks at LHC, we carry out a combined analysis of the mass spectra and fall-apart decays of the 1S-, 2S-, and 1P-wave ccc¯c¯ states in a nonrelativistic quark model. It is found that the X(6600) structure observed in the di-J/ψ invariant mass spectrum can be explained by the 1S-wave state T(4c)0++(6550). This structure may also bear some feed-down effects from the higher 2S and/or 1P tetraquark states. The X(6900) structure observed in both the di-J/ψ and J/ψψ(2S) channels can be naturally explained by the 2S-wave state T(4c)0++(6957). The small shoulder structure around 6.2–6.4 GeV observed at CMS and ATLAS may be due to the feed-down effects from some 1P-wave states with C=−1 and/or some 2S-wave states with JPC=0++. Other decay channels are implied in such a scenario and they can be investigated by future experimental analyses. Considering the large discovery potential at LHC, we also present predictions for the bbb¯b¯ states which can be searched for in the future. Published by the American Physical Society 2024