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arxiv: 2604.14716 · v1 · submitted 2026-04-16 · ✦ hep-ex · hep-ph

Charmed baryon decays at BESIII

Xudong Yu (on behalf of the BESIII Collaboration) This is my paper

Pith reviewed 2026-05-10 09:24 UTC · model grok-4.3

classification ✦ hep-ex hep-ph
keywords charmed baryonsemi-leptonic decaygraph neural networkdecay asymmetryW-exchangebranching fractionpartial wave analysis
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The pith

Rare semi-leptonic decay of charmed baryon to neutron observed using graph neural network

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

The paper reports results from a large data sample of charmed baryon pairs produced in electron-positron collisions. The central result is the first observation of the decay Lambda_c^+ to neutron, positive electron, and neutrino, isolated via a graph neural network. It also gives the initial measurement of the asymmetry parameter in the decay Lambda_c^+ to Xi^0 and K^+, a process that occurs purely through W-boson exchange. Additional measurements cover inclusive branching fractions, partial wave decompositions of three-body modes, Cabibbo-suppressed channels, and neutral kaon asymmetries. These data points test theoretical descriptions of how charm quarks decay inside baryons.

Core claim

The paper establishes the observation of the rare semi-leptonic decay Lambda_c^+ to neutron electron neutrino through multivariate selection with a graph neural network on the full data set. It simultaneously reports the first determination of the decay asymmetry in the pure W-exchange channel Lambda_c^+ to Xi^0 K^+. Complementary results include branching fraction measurements for the inclusive modes Lambda_c^+ to X electron neutrino and anti-Lambda_c to anti-neutron X, together with amplitude analyses of Lambda_c^+ to Lambda pi^+ pi^0 and Lambda_c^+ to Lambda pi^+ eta.

What carries the argument

The graph neural network classifier that isolates the rare signal from background in the semi-leptonic channel.

If this is right

  • The observed decay rate can be compared directly with predictions from quark models or lattice calculations for semi-leptonic charmed baryon transitions.
  • The measured asymmetry in the W-exchange decay supplies a new constraint on non-leptonic weak interaction amplitudes.
  • The inclusive branching fractions serve as normalization references for other decay channels of the same baryon.
  • The partial wave results map the resonant substructure that appears in multi-pion final states.

Where Pith is reading between the lines

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

  • Application of graph neural networks to other rare decay searches could increase sensitivity in heavy-flavor experiments.
  • The new data may help clarify why certain decay patterns differ between charmed baryons and charmed mesons.
  • Higher-statistics samples could allow extraction of form factors or angular distributions in the observed channels.

Load-bearing premise

The graph neural network training and background modeling assumptions correctly isolate the rare signal without introducing large biases or false positives.

What would settle it

An independent analysis of the same data set that uses a different selection method or omits the graph neural network and finds no excess events in the signal region would falsify the observation.

Figures

Figures reproduced from arXiv: 2604.14716 by Xudong Yu (on behalf of the BESIII Collaboration).

Figure 1
Figure 1. Figure 1: Left and middle: GNN-output distributions for [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Left: MBC distributions for Λ + c → pπ 0 and Λ + c → pη before the DNN selection. Middle: the corresponding distributions after the DNN selection. Right: comparison of the measured branching fraction with theoretical predictions. R(Λ + c → pK0 L,S π +π − ) = −0.027 ± 0.048, and R(Λ + c → pK0 L,S π 0 ) = −0.015 ± 0.046 [15]. These measurements provide useful input for searches for doubly Cabibbo-suppressed … view at source ↗
Figure 3
Figure 3. Figure 3: Comparison of experimental results for branching fraction and decay asymmetry of [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Top panels: projections of the fit results for [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
read the original abstract

BESIII has accumulated 4.5 fb$^{-1}$ of $e^+e^-$ collision data in the 4.6 to 4.7 GeV energy range, corresponding to the world's largest sample of $\Lambda_c^+\bar{\Lambda}_c^-$ pairs. This paper summarizes recent BESIII results on charmed-baryon decays, including the observation of the rare semi-leptonic decay $\Lambda_c^+\to ne^+\nu_e$ using a Graph Neural Network, the first measurement of the decay asymmetry in the pure $W$-exchange decay $\Lambda_c^+\to\Xi^0K^+$, and branching fraction measurements of the inclusive decays $\Lambda_c^+\to Xe^+\nu_e$ and $\bar{\Lambda}_c^-\to \bar{n}X$. We also report partial wave analyses of $\Lambda_c^+\to\Lambda\pi^+\pi^0$ and $\Lambda_c^+\to\Lambda\pi^+\eta$, measurements of Cabibbo-suppressed decays such as $\Lambda_c^+\to p\pi^0$, and studies of $K_S^0-K_L^0$ asymmetries in $\Lambda_c^+$ decays.

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

0 major / 3 minor

Summary. This paper summarizes recent results from the BESIII collaboration on charmed baryon decays, utilizing a data sample of 4.5 fb^{-1} collected at center-of-mass energies from 4.6 to 4.7 GeV. It highlights the observation of the rare semileptonic decay Λ_c^+ → n e^+ ν_e using a Graph Neural Network, the first measurement of the decay asymmetry in the pure W-exchange decay Λ_c^+ → Ξ^0 K^+, branching fraction measurements for inclusive decays Λ_c^+ → X e^+ ν_e and Λ_c^- → n-bar X, partial wave analyses of Λ_c^+ → Λ π^+ π^0 and Λ_c^+ → Λ π^+ η, measurements of Cabibbo-suppressed decays such as Λ_c^+ → p π^0, and studies of K_S^0 - K_L^0 asymmetries in Λ_c^+ decays.

Significance. If the reported results hold, they provide important new experimental inputs to heavy-flavor physics, particularly for rare semileptonic decays and asymmetry parameters in charmed baryons. These data can constrain form-factor models, test isospin relations, and probe W-exchange mechanisms, with the large BESIII sample enabling measurements that were previously inaccessible.

minor comments (3)
  1. [Abstract] The abstract does not include statistical significances, central values, or uncertainties for the key new results (e.g., the GNN-based observation or the asymmetry parameter), which would allow readers to assess the claims at a glance without consulting the referenced primary papers.
  2. A summary table compiling all reported branching fractions, asymmetries, and their uncertainties would improve readability and facilitate comparison across the multiple analyses presented.
  3. Particle notation (e.g., subscripts and superscripts for Λ_c^+, Ξ^0, K_S^0) should be checked for consistent LaTeX formatting throughout the text and figures.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript summarizing recent BESIII results on charmed baryon decays and for the positive assessment of its significance. The recommendation for minor revision is noted. However, the report contains no specific major comments requiring response or changes to the text.

Circularity Check

0 steps flagged

No circularity: direct experimental measurements from data

full rationale

This is a concise summary paper reporting multiple BESIII experimental results on charmed baryon decays, including observations and branching fractions extracted from collision data. No theoretical derivation chain, equations, or parameter fittings exist within the document that could reduce to self-inputs by construction. The GNN-based signal isolation and background modeling are acknowledged as load-bearing but are not re-derived here; they reside in referenced primary papers. All quantities are direct measurements, making the paper self-contained against external benchmarks with no self-definitional, fitted-prediction, or self-citation circularity.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

This experimental summary relies on standard particle physics assumptions rather than introducing new theoretical constructs; no free parameters or invented entities are defined in the abstract.

axioms (1)
  • domain assumption Standard Model conservation laws and particle identification techniques apply to the analyzed decays
    Implicit foundation for all branching fraction and asymmetry measurements in high-energy physics experiments.

pith-pipeline@v0.9.0 · 5511 in / 1310 out tokens · 53950 ms · 2026-05-10T09:24:17.515160+00:00 · methodology

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Reference graph

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