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Main Authors: Anwar, Muhammad Naeem, Burns, Timothy J.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.04014
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author Anwar, Muhammad Naeem
Burns, Timothy J.
author_facet Anwar, Muhammad Naeem
Burns, Timothy J.
contents We consider how the recent CMS measurements of the masses and quantum numbers of $X(6600)$, $X(6900)$ and $X(7100)$ can help to reveal the internal structure of these apparent $cc\bar{c}\bar{c}$ tetraquark states. The measured $J^{PC} = 2^{++}$ quantum numbers of $X(6600)$ are consistent with our previous prediction, and imply the existence of lighter $0^{++}$ partner $X(6400)$ which also decays to $J/ψJ/ψ$. There may already be indications for this scalar partner in the recent CMS data fits, which include a Breit-Wigner peak with mass around 6400~MeV. We give predictions for the masses and decay properties of the scalar and other partner states, which are key experimental tests to discriminate between quark and diquark models. We urge closer experimental scrutiny in this mass region, to establish an S-wave multiplet of $cc \bar c \bar c$ states (the first of its kind), leading to a breakthrough in exotic hadron research and our understanding of exclusively heavy quark exotics.
format Preprint
id arxiv_https___arxiv_org_abs_2605_04014
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Predictions for the scalar partner of the LHC tetraquark $X(6600)$
Anwar, Muhammad Naeem
Burns, Timothy J.
High Energy Physics - Phenomenology
High Energy Physics - Experiment
High Energy Physics - Lattice
We consider how the recent CMS measurements of the masses and quantum numbers of $X(6600)$, $X(6900)$ and $X(7100)$ can help to reveal the internal structure of these apparent $cc\bar{c}\bar{c}$ tetraquark states. The measured $J^{PC} = 2^{++}$ quantum numbers of $X(6600)$ are consistent with our previous prediction, and imply the existence of lighter $0^{++}$ partner $X(6400)$ which also decays to $J/ψJ/ψ$. There may already be indications for this scalar partner in the recent CMS data fits, which include a Breit-Wigner peak with mass around 6400~MeV. We give predictions for the masses and decay properties of the scalar and other partner states, which are key experimental tests to discriminate between quark and diquark models. We urge closer experimental scrutiny in this mass region, to establish an S-wave multiplet of $cc \bar c \bar c$ states (the first of its kind), leading to a breakthrough in exotic hadron research and our understanding of exclusively heavy quark exotics.
title Predictions for the scalar partner of the LHC tetraquark $X(6600)$
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
High Energy Physics - Lattice
url https://arxiv.org/abs/2605.04014