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arxiv: 2605.10023 · v1 · submitted 2026-05-11 · ✦ hep-ex

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Search for invisible decays of light mesons via J/psi to VP (V=ω/φ,P=η/η') decays at STCF

Vindhyawasini Prasad, WeiMin Song, Xu Gao, Yihang Xia, Zhibo Tao

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Pith reviewed 2026-05-12 03:07 UTC · model grok-4.3

classification ✦ hep-ex
keywords invisible decaylight mesonJ/ψ decaySTCFupper limitdark matterbranching fractionMonte Carlo
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The pith

Projected STCF data can set upper limits on invisible decays of ω, φ, η and η' mesons at a few times 10^{-7}.

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

The paper conducts a feasibility study for detecting invisible decays of light mesons through the decay chain J/ψ → V P at the proposed Super τ-Charm Facility. It scales an inclusive Monte Carlo sample of 1.3 × 10^9 events to the expected annual yield of 3.4 × 10^12 J/ψ events and applies a traditional analysis to project 90% confidence level upper limits. These limits target possible signals from light dark matter or other new physics that would produce no detectable final-state particles. The work also indicates that machine learning methods could improve the reach toward theoretical expectations for such decays.

Core claim

By scaling an inclusive Monte Carlo sample of 1.3 × 10^9 J/ψ events to the expected STCF statistics, the analysis sets 90% CL upper limits of B(ω → invisible) < 3.7 × 10^{-7}, B(φ → invisible) < 8.9 × 10^{-7}, B(η → invisible) < 1.8 × 10^{-7} and B(η' → invisible) < 4.1 × 10^{-7}.

What carries the argument

The J/ψ → V P decay chain (V = ω/φ, P = η/η') used to tag events and infer invisible decays of the partner meson from missing energy and momentum after reconstructing the visible products.

If this is right

  • The projected limits would tighten constraints on models of light dark matter that couple to these mesons.
  • The results show that high-statistics J/ψ samples at STCF enable rare invisible-decay searches that were previously inaccessible.
  • Deep learning techniques are identified as a route to further improve the limits toward theoretical predictions for light dark matter.
  • The tagging method via J/ψ → V P provides a clean experimental handle for missing-energy searches in light-meson systems.

Where Pith is reading between the lines

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

  • The same scaling approach could be applied to other proposed high-luminosity tau-charm or beauty factories to compare projected sensitivities across facilities.
  • Confirmation of these limits would motivate dedicated theoretical calculations of expected invisible rates from specific dark-sector models.
  • Combining the projected limits with existing bounds from other experiments would further restrict the parameter space for light invisible particles.
  • Real detector data may require adjustments to the background modeling used in the toy projections, altering the final reach.

Load-bearing premise

The inclusive Monte Carlo sample and its scaling to full STCF luminosity accurately represent future detector performance, background composition, and reconstruction efficiencies.

What would settle it

Real STCF data showing an excess of events with missing mass or energy consistent with invisible decays at a rate above the projected upper limits would indicate that the sensitivity estimates are too optimistic.

Figures

Figures reproduced from arXiv: 2605.10023 by Vindhyawasini Prasad, WeiMin Song, Xu Gao, Yihang Xia, Zhibo Tao.

Figure 1
Figure 1. Figure 1: Invariant mass recoiling against the selected [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Fit to the mV recoil distribution for ω (left) and ϕ (right) signals. The projected toy data sample is shown by the dots with error bars. The solid blue, dashed green, dotted cyan and long￾dashed pink curves represent the overall fit results, signal, peaking and non-peaking backgrounds, respectively. 0.4 0.5 0.6 0.7 0.8 0.9 1 )2 (GeV/c mrecoil φ 0 100 200 300 400 500 600 700 Entries/0.0095 Inclusive J/ψ MC… view at source ↗
Figure 3
Figure 3. Figure 3: Invariant mass recoiling against the selected [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Fit to the mrecoil ϕ distribution for η (left) and η ′ (right) signals. The projected toy data sample is shown by the dots with error bars. The solid blue, long-dashed pink, and dashed green curves represent the overall fit results, signal and backgrounds, respectively. by the MC simulated shape and the background PDF is modeled with a first order polynomial function. The ML fit is performed and the signal… view at source ↗
Figure 5
Figure 5. Figure 5: Projections of the 2D fit to mω π+π−π0 and m η π+π−π0 distributions. The projected toy data sample is shown by the dots with error bars, the signals by the dashed green curve, BKGI by the long-dashed pink curve, BKGII with ω intermediate state by the dotted cyan curve, BKGII with the η intermediate state by the dash-dotted red curve, and the total fit by the solid blue curve. The remaining backgrounds are … view at source ↗
Figure 6
Figure 6. Figure 6: Projections of the 2D fit to m ϕ K+K− and m η π+π−π0 . The projected toy data sample is shown by the dots with error bars, the signals by the dashed green curve, BKGI by the long-dashed pink curve, BKGII with ϕ intermediate state by the dotted cyan curve, BKGII with the η intermediate state by the dash-dotted red curve, and the total fit by the solid blue curve. measured to be (7.87 ± 0.05) × 10−4 , which … view at source ↗
Figure 7
Figure 7. Figure 7: Projections of the 2D fit to mK+K− and mγγ. The projected toy data sample is shown by the dots with error bars, the signals by the dashed green curve, BKGI by the long-dashed pink curve, BKGII with ϕ intermediate state by the dotted cyan curve, BKGII with the η intermediate state by the dash-dotted red curve, and the total fit by the solid blue curve. 1 1.02 1.04 1.06 1.08 1.1 )2 - (GeV/c K + mK 2 10 3 10 … view at source ↗
Figure 8
Figure 8. Figure 8: Projections of the 2D fit to mK+K− and mγγ. The projected toy data sample is shown by the dots with error bars, the signals by the dashed green curve, BKGI by the long-dashed pink curve, BKGII with ϕ intermediate state by the dotted cyan curve, BKGII with the η ′ intermediate state by the dash-dotted red curve, and the total fit by the solid blue curve. 5. Results and outlook With the generated projected t… view at source ↗
read the original abstract

We present a preliminary feasibility study of searches for invisible decays of light mesons via $J/\psi \to VP$ $(V=\omega/\phi,P=\eta/\eta')$ using a traditional analytical method at the proposed Super $\tau$-Charm facility (STCF) which is expected to accumulate $3.4\times10^{12}$ $J/\psi$ events per year, based on an inclusive Monte Carlo sample of $1.3 \times 10^{9}$ $J/\psi$ events. The upper limits on the invisible decay branching fractions at the 90\% confidence level are set as $\mathcal{B}(\omega \to invisible) < 3.7 \times 10^{-7}$, $\mathcal{B}(\phi \to invisible) < 8.9 \times 10^{-7}$, $\mathcal{B}(\eta \to invisible) < 1.8 \times 10^{-7}$ and $\mathcal{B}(\eta' \to invisible) < 4.1 \times 10^{-7}$, respectively, using a projected toy data corresponding to the expected STCF statistics. By using the machine learning technique such as Deep Learning, the upper limit may be further improved to approach theoretical predictions for light dark matter.

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.

Referee Report

1 major / 2 minor

Summary. The manuscript presents a preliminary feasibility study for searches of invisible decays of the light mesons ω, φ, η, and η' produced in J/ψ → V P decays at the proposed Super τ-Charm Facility (STCF). Based on an inclusive Monte Carlo sample of 1.3 × 10^9 J/ψ events, the authors scale to the expected annual luminosity of 3.4 × 10^12 J/ψ events and use toy data to set projected 90% confidence level upper limits on the invisible branching fractions: B(ω → invisible) < 3.7 × 10^{-7}, B(φ → invisible) < 8.9 × 10^{-7}, B(η → invisible) < 1.8 × 10^{-7}, and B(η' → invisible) < 4.1 × 10^{-7}. The study employs a traditional analytical method with missing momentum reconstruction and notes that deep learning could further improve the sensitivity.

Significance. If the Monte Carlo scaling assumptions hold, these projected limits would represent a significant improvement over current constraints and could probe regions of parameter space for light dark matter models. The work highlights the physics potential of the STCF for rare decay searches using the J/ψ → VP tag. Strengths include the use of both conventional and suggested advanced analysis techniques. However, the projected nature means the actual impact depends on the realization of the detector performance as assumed.

major comments (1)
  1. [§4] The upper limits quoted in the abstract and §4 are obtained by scaling the inclusive MC sample of 1.3×10^9 events to 3.4×10^12 events via toy data. This scaling assumes that background rates, efficiencies, and missing momentum resolution scale linearly without additional contributions from pile-up, machine backgrounds, or changes in detector response at the higher luminosity; no quantitative study of these effects is provided, which is load-bearing for the validity of the quoted limits such as B(η → invisible) < 1.8 × 10^{-7}.
minor comments (2)
  1. [Abstract] The abstract mentions 'a traditional analytical method' but does not specify the details of the selection criteria or fitting procedure used in the projection.
  2. Consider adding a table summarizing the expected signal and background yields in the toy data for each channel to improve clarity.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the detailed review and constructive feedback on our preliminary feasibility study. We address the major comment below and agree that additional clarification on the scaling assumptions is needed to strengthen the manuscript. The revisions will be incorporated in the next version.

read point-by-point responses

  1. Referee: [§4] The upper limits quoted in the abstract and §4 are obtained by scaling the inclusive MC sample of 1.3×10^9 events to 3.4×10^12 events via toy data. This scaling assumes that background rates, efficiencies, and missing momentum resolution scale linearly without additional contributions from pile-up, machine backgrounds, or changes in detector response at the higher luminosity; no quantitative study of these effects is provided, which is load-bearing for the validity of the quoted limits such as B(η → invisible) < 1.8 × 10^{-7}.

    Authors: We appreciate the referee pointing out this key assumption in our projection. As stated in the manuscript, this is a preliminary feasibility study based on an inclusive Monte Carlo sample of 1.3×10^9 J/ψ events, scaled to the expected 3.4×10^12 events per year at STCF using toy data. The linear scaling of backgrounds, efficiencies, and missing-momentum resolution is a standard approach for such early projections when full high-luminosity detector simulations (including pile-up and machine backgrounds) are not yet available. We acknowledge that non-linear effects from pile-up, machine backgrounds, or changes in detector response could modify the sensitivity. In the revised manuscript, we will add a new paragraph in Section 4 explicitly discussing these assumptions, stating that the quoted limits represent optimistic projections under ideal conditions, and noting that a more detailed simulation study will be required once the STCF detector design and luminosity-dependent backgrounds are better defined. This will not change the numerical results but will better contextualize their scope. revision: partial

Circularity Check

0 steps flagged

Projected upper limits from scaled MC simulation exhibit no circularity

full rationale

The paper conducts a feasibility study by taking a fixed inclusive MC sample of 1.3e9 J/ψ events to model efficiencies, backgrounds, and missing-momentum reconstruction, then scaling the statistics linearly to generate toy data at the projected STCF luminosity of 3.4e12 events. Upper limits are computed from this toy data via standard statistical procedures. No equation or step defines the reported branching-fraction limits in terms of themselves, renames a fitted parameter as a prediction, or relies on a self-citation chain for the central result. The MC scaling assumptions are external inputs and do not reduce the derivation to its own outputs.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The projections rest on standard Monte Carlo modeling of detector response and the assumption that the stated annual J/ψ yield will be achieved; no new entities or ad-hoc axioms are introduced.

pith-pipeline@v0.9.0 · 5556 in / 1160 out tokens · 91978 ms · 2026-05-12T03:07:47.755704+00:00 · methodology

discussion (0)

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