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Pseudoscalar production at omega omega threshold in J/psi -> gamma omega omega

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Bes Collaboration

High Energy Physics - Experiment · Submitted 24 Apr 2006 · 42 references

Pith's verdict: Solid BES measurement of eta(1760) → omega omega, but the near-threshold line-shape model needs close scrutiny before the mass/width are taken at face value.

T0 · AI review

How this review was made: An AI referee (deepseek-v4-flash) read the paper on August 28, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

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  3. T2 Compute The paper's code or calculations re-run with the same results.
  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

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Cite ▾
arXiv IDhep-ex/0604045 (version 3)
Pith IDUIJJW5Y4, Pith's permanent record of this paper and its review
CitationBES Collaboration. "Pseudoscalar production at omega omega threshold in J/psi -> gamma omega omega." arXiv:hep-ex/0604045 (2006). https://pith.science/paper/UIJJW5Y4
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The paper

The paper claims

The $\omega\omega$ peak in $J/\psi\to\gamma\omega\omega$ is predominantly a pseudoscalar resonance, identified as $\eta(1760)$.

The reading

This paper reports that in radiative $J/\psi$ decays to a photon and two omega mesons, the $\omega\omega$ invariant-mass spectrum shows a clear peak at about 1.76 GeV/$c^2$, just above the $\omega\omega$ threshold. The angular correlations among the decay products already indicate that this peak is predominantly pseudoscalar, and a partial wave analysis confirms $J^{PC}=0^{-+}$ with only small $0^{++}$ and $2^{++}$ admixtures. Interpreting the peak as the $\eta(1760)$ resonance, the analysis measures its mass as $1744\pm10\pm15$ MeV/$c^2$ and its width as $244^{+24}_{-21}\pm25$ MeV/$c^2$, with product branching fraction $Br(J/\psi\to\gamma\eta(1760))\cdot Br(\eta(1760)\to\omega\omega)=(1.98\pm0.08\pm0.32)\times10^{-3}$. The result matters because it fixes the quantum numbers of an excited pseudoscalar meson in a final state where threshold effects are large, and it gives a concrete decay rate for a state that had been identified mainly in other channels.

What carries the argument

The carrying mechanism is a partial wave analysis of the $\omega\omega$ system: a coherent sum of amplitudes with definite $J^{PC}$ (dominant $0^{-+}$, small $0^{++}$ and $2^{++}$) is fitted to the joint distribution of the $\omega\omega$ mass and the helicity angles of the two $\omega$ decays. It is the angular part that has the discriminating power, because a pseudoscalar source produces a characteristic pattern of correlations among the pions from the two $\omega$ decays that a scalar or tensor source cannot reproduce except through its own fitted amplitudes. The analysis also accounts for the detector acceptance and uses the interference among partial waves to separate the resonance signal from the non-resonant background.

Extended reading notes

Core claim

The central claim is that the $\omega\omega$ mass enhancement below 2 GeV/$c^2$ in $J/\psi\to\gamma\omega\omega$ is not a kinematic reflection of the threshold but a genuine resonance, and that this resonance is overwhelmingly pseudoscalar. The angular correlations alone disfavor the scalar and tensor alternatives, and the partial wave analysis quantifies those small contributions while extracting the resonance parameters. The fitted mass and width place the state at the $\eta(1760)$, so the paper effectively establishes the $\eta(1760)\to\omega\omega$ decay and its product branching fraction at the level of $2\times10^{-3}$.

Load-bearing premise

The analysis assumes the list of amplitudes it includes—one pseudoscalar resonance plus small scalar and tensor terms, with a specific choice of line shapes and backgrounds—is complete enough that the fitted pseudoscalar signal is not an artifact of a misspecified model.

Editorial extensions

If this is right

  • The quantum numbers of the $\eta(1760)$ are pinned down as $J^{PC}=0^{-+}$ from this channel, removing ambiguity about its identity.
  • Because the resonance sits just above the $\omega\omega$ threshold and its width is comparable to its excess energy, threshold effects are significant in the measured line shape.
  • The product branching fraction near $2\times10^{-3}$ gives a quantitative target for other experiments and for theoretical estimates of $\eta(1760)$ decays.
  • The small $0^{++}$ and $2^{++}$ contributions provide a baseline for searching for other resonances in the same mass region.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The paper's line shape assumes a single Breit-Wigner; a coupled-channel analysis that includes the opening of the $\omega\omega$ threshold explicitly could shift the fitted width, so the $244$ MeV width should be read with that model dependence in mind.
  • A model-independent consistency check would be to bin the data finely in $m_{\omega\omega}$ and compare the measured angular moments with the pure pseudoscalar prediction; any systematic deviation would reveal missing partial waves.
  • If this state is the radial excitation of the $\eta$ or $\eta'$, the $\omega\omega$ coupling measured here could be combined with $\rho\rho$ and $K^*\bar{K}^*$ modes to test decay relations among excited pseudoscalar mesons.
Original abstract

The decay channel J/\psi->gamma omega omega, omega -> pi+ pi- pi0 is analyzed using a sample of 5.8x10^7 J/psi events collected with the BESII detector. The omega omega invariant mass distribution peaks at 1.76 GeV/c^2, just above the omega omega threshold. Analysis of angular correlations indicate that the omega omega system below 2 GeV/c^2 is predominantly pseudoscalar. A partial wave analysis confirms the predominant pseudoscalar structure, together with small 0^{++} and 2^{++} contributions, and yields a pseudoscalar mass M = 1744 \pm 10 (stat) \pm 15 (syst) MeV/c^2, a width Gamma = 244^{+24}_{-21} (stat) \pm 25 (syst) MeV/c^2, and a product branching fraction Br(J/psi-> gamma eta(1760)) \cdot Br(\eta(1760)->omega omega) = (1.98 \pm 0.08 (stat) \pm 0.32 (syst)) x 10^{-3}.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,897 input tokens, $0.0002 reported.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.14 · human participants 0.01 · controlled comparison 0.02 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.07 · mentions code or data availability 0.01.

The abstract, sentence by sentence

arXiv listing abstract v3. Results and the main claim are underlined; .

The decay channel J/\psi->gamma omega omega, omega -> pi+ pi- pi0 is analyzed using a sample of 5.8x10^7 J/psi events collected with the BESII detector. The omega omega invariant mass distribution peaks at 1.76 GeV/c^2, just above the omega omega threshold. Analysis of angular correlations indicate that the omega omega system below 2 GeV/c^2 is predominantly pseudoscalar. A partial wave analysis confirms the predominant pseudoscalar structure, together with small 0^{++} and 2^{++} contributions, and yields a pseudoscalar mass M = 1744 \pm 10 (stat) \pm 15 (syst) MeV/c^2, a width Gamma = 244^{+24}_{-21} (stat) \pm 25 (syst) MeV/c^2, and a product branching fraction Br(J/psi-> gamma eta(1760)) \cdot Br(\eta(1760)->omega omega) = (1.98 \pm 0.08 (stat) \pm 0.32 (syst)) x 10^{-3}.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 The decay channel J/\psi->gamma omega omega, omega -> pi+ pi- pi0 is analyzed using a sample of 5.8x10^7 J/psi events collected with the BESII detector. method 0.93 0.95 0.02 asserted 0.94
s1 The omega omega invariant mass distribution peaks at 1.76 GeV/c^2, just above the omega omega threshold. result 1.00 0.92 0.10 asserted 1.00
s2 Analysis of angular correlations indicate that the omega omega system below 2 GeV/c^2 is predominantly pseudoscalar. result 0.92 0.93 0.56 asserted 0.53
s3 A partial wave analysis confirms the predominant pseudoscalar structure, together with small 0^{++} and 2^{++} contributions, and yields a pseudoscalar mass M = 1744 \pm 10 (stat) \pm 15 (syst) MeV/c^2, a width Gamma = 244^{+24}_{-21} (stat) \pm 25 (syst) MeV/c^2, and a product branching fraction Br(J/psi-> gamma eta(1760)) \cdot Br(\eta(1760)->omega omega) = (1.98 \pm 0.08 (stat) \pm 0.32 (syst)) x 10^{-3}. result 1.00 0.96 0.75 asserted 1.00

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 0.72.

What was examined, and what was not

sources read
  • arXiv listing abstract v3
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. FIG. 1: (a) The
Figure 2. FIG. 2: (a) The 2(
Figure 3. FIG. 3: Distribution of
Figure 4. FIG. 4: The 2(
Figure 5. FIG. 5: Comparisons of angular distributions between data a

Figures reproduced from arXiv:hep-ex/0604045 by the authors.

References
How the literature uses it

2 arXiv papers cite this in 2 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 1 sentence without a confident label

Uses its data or values 1 paper
  • In fact, the experimental results quoted for the partial widths should be considered as upper values as they ignore the possibility of decay into four or more pions, since at least decay of $f_0(1710)$ into two $ω$ mesons and further to six pions has been seen in $J/ψ→γf_0(1710)$ (in fact at the level of 75% of the rate into two pions , so that the holographic prediction may not be very far off) [This interpretation of the data published in [ref] ignores the possibility that these decays could be attributed to a separate isoscalar such as the $f_0(1790)$ proposed in [ref] .] The only remaining major mismatch between existing experimental data for $f_0(1710)$ [ref] and the prediction of the Witten-Sakai-Sugimoto model thus appears to be the rather high rate for decay into four pions, which is predicted by the latter to proceed through $2ρ$ and $ρππ$ at the level of about twice the rate in

    Nonchiral enhancement of scalar glueball decay in the Witten-Sakai-Sugimoto model · Introduction · 0.86

Discussion

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