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arxiv: 2606.18892 · v1 · pith:W7VDXFDCnew · submitted 2026-06-17 · ✦ hep-ph

Radiative decay of fully-heavy tetraquark into quarkonium

Hao Yang , Songlin Lyu , Bingwei Long This is my paper

Pith reviewed 2026-06-26 20:30 UTC · model grok-4.3

classification ✦ hep-ph
keywords tetraquarksradiative decaysfully heavy quarksNRQCDcharmoniumbottomoniumX(6200)
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The pith

Radiative decays of the fully-charm tetraquark to gamma J/psi have widths around 1 MeV and offer a low-background search channel near the J/psi J/psi threshold.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper calculates radiative decay widths of fully heavy tetraquarks and mixed heavy-flavor tetraquarks into quarkonium plus photon states using the nonrelativistic QCD factorization framework. Numerical results show that the fully charm tetraquark T4c decays to gamma J/psi or gamma eta_c with widths of order 1 MeV. The gamma J/psi final state receives less experimental background near the J/psi J/psi threshold, making it a practical channel for searching possible tetraquark resonances such as X(6200). The same framework yields much smaller widths for bottom tetraquarks and shows that mixed bc states prefer annihilation into bottomonium over charmonium by several orders of magnitude.

Core claim

Within the NRQCD factorization framework the decay widths of the fully-charm tetraquark T4c into gamma J/psi (eta_c) are around 1 MeV while the gamma J/psi signal channel receives less experimental background near the J/psi J/psi threshold, providing a compelling way to search for possible tetraquark states X(6200).

What carries the argument

NRQCD factorization framework applied to radiative transitions of tetraquarks with assumed quantum numbers and wave-function overlaps.

If this is right

  • These radiative decay modes can be measured in future experiments.
  • The modes help distinguish the inner structure of fully heavy tetraquarks.
  • For fully bottom tetraquarks the radiative widths are suppressed to the tens of eV level.
  • Mixed T_bc bbar cbar states decay preferentially to gamma Upsilon over gamma J/psi by three to four orders of magnitude.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Confirmation of the predicted widths would constrain the spatial wave-function overlaps adopted for the tetraquark states.
  • The same NRQCD machinery could be applied to other electromagnetic or hadronic decay channels to test consistency across observables.
  • Non-observation in the gamma J/psi channel would favor alternative interpretations of the X(6200) region over a compact tetraquark.

Load-bearing premise

The NRQCD factorization framework applies directly to the radiative transitions of these tetraquark states with the assumed quantum numbers and wave-function overlaps used in the calculation.

What would settle it

An experimental measurement finding the partial width of T4c to gamma J/psi well below 1 MeV or no resonant signal in the gamma J/psi invariant-mass distribution near the J/psi J/psi threshold despite adequate integrated luminosity.

Figures

Figures reproduced from arXiv: 2606.18892 by Bingwei Long, Hao Yang, Songlin Lyu.

Figure 1
Figure 1. Figure 1: FIG. 1: Two representative leading-order Feynman diagrams for the radiative decay [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
read the original abstract

We present a comprehensive study of the radiative decays of fully heavy tetraquarks ($T_{4c}$, $T_{4b}$) and mixed heavy-flavor tetraquarks ($T_{bc\bar{b}\bar{c}}$) into charmonium/bottomonium states, within the nonrelativistic QCD factorization framework. Numerical result indicates that the decay widths of fully charm tetraquark $T_{4c}$ into $\gamma J/\psi (\eta_c)$ are around 1 MeV. Crucially, the $\gamma J/\psi$ signal channel receives less experimental background near the $J/\psi J/\psi$ threshold, providing a compelling way to search for the possible tetraquark states X(6200). For $T_{4b}$, the decay width is highly suppressed by the bottom quark mass, just lying in tens eV level. We further find that the decay widths of $T_{bc\bar{b} \bar{c}} \to \gamma \Upsilon$ exceed those to $\gamma J/\psi$ by 3-4 orders of magnitude, indicating preferential $c\bar{c}$-pair annihilation over $b\bar{b}$. These radiative decay modes can be measured in the future experiments, and are helpful to understand the inner structure of the full heavy tetraquark.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Circularity Check

0 steps flagged

NRQCD factorization yields independent numerical widths; no reduction to inputs by construction

full rationale

The derivation applies standard NRQCD factorization to tetraquark radiative transitions, taking wave-function overlaps and quantum numbers as external model inputs rather than deriving them from the target widths. No quoted equations or self-citations show a fitted parameter being relabeled as a prediction, a self-definitional loop, or a load-bearing uniqueness theorem imported from the same authors. The ~1 MeV result is a direct evaluation within the framework; uncertainty in the overlap affects the output magnitude but does not make the calculation tautological. This is a conventional model calculation whose central content remains independent of its own outputs.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review yields no explicit free parameters or invented entities; typical NRQCD tetraquark calculations rely on fitted color-octet matrix elements and assumed tetraquark wave functions, but none are listed here.

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Reference graph

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