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arxiv: 2605.14899 · v1 · pith:EKTXMHQMnew · submitted 2026-05-14 · ✦ hep-ph

CP asymmetries in Dto K⁰_(S,L)P and Dto K⁰_(S,L)V decays

Ying-Xin Lai , Di Wang This is my paper

Pith reviewed 2026-06-30 20:19 UTC · model grok-4.3

classification ✦ hep-ph
keywords CP violationD meson decaysneutral kaon mixingCabibbo-favored amplitudesdoubly Cabibbo-suppressed amplitudestopological diagram approachtime-dependent asymmetries
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The pith

CP asymmetries from amplitude interference and kaon mixing reach order 10^{-3} in four D decays.

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

The paper derives time-dependent and time-integrated CP asymmetries for D decays to neutral kaons paired with pseudoscalars or vectors. It includes D0 mixing and KL modes explicitly. Hadronic parameters are obtained from a global fit to branching fractions in the topological diagram approach. This reduces the mismatch between prediction and data for the KS-KL asymmetries in D0 to omega and phi modes. The interference between Cabibbo-favored and doubly Cabibbo-suppressed amplitudes plus kaon mixing produces O(10^{-3}) effects in the D+ to KS pi+, Ds+ to KS K+, D0 to KS rho0, and D0 to KS phi channels, with the difference between the first two modes testable soon.

Core claim

The central claim is that the interference between Cabibbo-favored and doubly Cabibbo-suppressed amplitudes with neutral kaon mixing generates CP-violating effects of order 10^{-3} in the D+→K0Sπ+, D+s→K0SK+, D0→K0Sρ0, and D0→K0Sϕ modes. The formulas account for D0-D0bar mixing and KL final states for the first time. Hadronic parameters extracted via global fit of branching fractions in the topological diagram approach mitigate the tension between theory and experiment for the KS-KL asymmetries in the D0→K0S,Lω and D0→K0S,Lϕ modes. The difference between the CP asymmetries in D+→K0Sπ+ and D+s→K0SK+ is measurable at LHCb and Belle II.

What carries the argument

The topological diagram approach, which extracts hadronic parameters from a global fit to branching fractions and thereby fixes the sizes of the interfering Cabibbo-favored and doubly Cabibbo-suppressed amplitudes that drive the CP asymmetries together with kaon mixing.

If this is right

  • The KS-KL asymmetry tension in D0→K0S,Lω and D0→K0S,Lϕ is reduced by the new parameter extraction.
  • O(10^{-3}) CP-violating effects appear in the four specified modes from the CF-DCS interference plus kaon mixing.
  • The formulas now include D0 mixing and KL modes explicitly for all channels considered.
  • The difference between the CP asymmetries in D+→K0Sπ+ and D+s→K0SK+ becomes experimentally accessible at LHCb and Belle II.

Where Pith is reading between the lines

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

  • If the predicted difference between the two charged-D modes is confirmed, it would provide a clean test of the relative sizes of the Cabibbo-favored and doubly Cabibbo-suppressed amplitudes without requiring new hadronic modeling.
  • The same parameter set can be used to forecast CP asymmetries in additional D decay channels not yet measured.
  • Observation of these 10^{-3} effects at the expected level would constrain the possible size of any beyond-Standard-Model contribution to the same observables.

Load-bearing premise

The hadronic parameters extracted via global fit of branching fractions in the topological diagram approach correctly determine the CP asymmetries in the listed modes.

What would settle it

A precision measurement of the time-integrated CP asymmetry in D+→K0Sπ+ that lies well below or above the 10^{-3} range would show whether the extracted parameters and interference mechanism produce the predicted size.

Figures

Figures reproduced from arXiv: 2605.14899 by Di Wang, Ying-Xin Lai.

Figure 1
Figure 1. Figure 1: FIG. 1: Schematic description of the chain decay [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: Schematic description of the chain decay [PITH_FULL_IMAGE:figures/full_fig_p007_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: Time-dependent CP asymmetries in the [PITH_FULL_IMAGE:figures/full_fig_p014_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4: Time-dependent CP asymmetries in the [PITH_FULL_IMAGE:figures/full_fig_p015_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5: The observable ∆ [PITH_FULL_IMAGE:figures/full_fig_p016_5.png] view at source ↗
read the original abstract

$D$ meson decays into neutral kaons involve both Cabibbo-favored and doubly Cabibbo-suppressed amplitudes as well as final-state kaon mixing, providing abundant sources of CP violation. In this work, we analyze CP asymmetries in the $D\to K^0_{S,L}P$ and $D\to K^0_{S,L}V$ decays, where $P$ and $V$ denote pseudoscalar and vector mesons respectively. The formulas of the time-dependent and time-integrated CP asymmetries in these modes are derived, in which the $D^0-\overline D^0$ mixing effects and the $K^0_L$ modes are considered for the first time. The hadronic parameters that determine CP asymmetries are extracted by the global fit of branching fractions within the topological diagram approach. A significant result is that the tension between theoretical predictions and experimental data for the $K_S^0-K_L^0$ asymmetries in $D^0\to K_{S,L}^0\omega$ and $D^0\to K_{S,L}^0\phi$ modes is mitigated. The CP-violating effects arising from the interference between Cabibbo-favored and doubly Cabibbo-suppressed amplitudes with neutral kaon mixing could reach to $\mathcal{O}(10^{-3})$ order in the $D^+\to K^0_S\pi^+$, $D^+_s\to K^0_SK^+$, $D^0\to K^0_S\rho^0$, and $D^0\to K^0_S\phi$ modes. The difference between the CP asymmetries in the $D^+\to K^0_S\pi^+$ and $D^+_s\to K^0_SK^+$ modes is available on LHCb and Belle II in the near future.

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. The manuscript analyzes CP asymmetries in D meson decays to neutral kaons plus a pseudoscalar or vector meson (D → K_{S,L}^0 P and D → K_{S,L}^0 V). It derives time-dependent and time-integrated CP asymmetry formulas that incorporate D^0-¯D^0 mixing and the K_L modes explicitly for the first time. Hadronic parameters are extracted from a global fit to branching fractions in the topological diagram approach. The central claims are that this framework mitigates the existing tension between theory and data for the K_S^0-K_L^0 asymmetries in the ω and ϕ modes, and that CP-violating effects from interference between Cabibbo-favored and doubly Cabibbo-suppressed amplitudes (with kaon mixing) reach O(10^{-3}) in the D^+ → K_S^0 π^+, D_s^+ → K_S^0 K^+, D^0 → K_S^0 ρ^0, and D^0 → K_S^0 ϕ channels, with the difference between the first two modes testable at LHCb and Belle II.

Significance. If the results hold, the work supplies concrete, testable predictions at the 10^{-3} level for CP violation in charm decays that lie within the sensitivity of current and near-future experiments. The explicit retention of D mixing and K_L modes in the time-integrated rates is a clear methodological advance over prior treatments and directly addresses the reported K_S^0-K_L^0 tension in the vector modes. The global fit to branching fractions within the topological diagram approach provides a systematic, data-driven determination of the hadronic parameters that enter the asymmetries.

minor comments (3)
  1. [abstract and §2] The abstract states that the formulas are derived 'in which the D^0-¯D^0 mixing effects and the K_L^0 modes are considered for the first time,' but the manuscript should explicitly compare the new time-integrated expressions to the earlier literature expressions (e.g., those omitting mixing) to quantify the numerical impact of each term.
  2. [§3 (parameter extraction)] The global fit to branching fractions is used to fix the hadronic parameters that enter the CP asymmetries; the manuscript should report the χ²/dof of that fit and the correlation matrix among the extracted parameters so that the propagated uncertainty on the O(10^{-3}) predictions can be assessed.
  3. [§4 (numerical results)] Table or figure presenting the numerical CP asymmetries for the four highlighted modes should include both the central values and the uncertainties propagated from the fit; without this, the claim that the effects 'could reach to O(10^{-3})' remains qualitative.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the positive assessment of our manuscript, including the recognition of the methodological advance in retaining D mixing and K_L modes, the data-driven extraction of hadronic parameters, and the concrete predictions at the 10^{-3} level. The recommendation for minor revision is noted. No major comments were provided in the report.

Circularity Check

0 steps flagged

No significant circularity; predictions use external branching-fraction data

full rationale

The paper derives time-dependent and time-integrated CP-asymmetry formulas that explicitly retain D^0-Dbar^0 mixing and K_L^0 modes. Hadronic parameters in the topological-diagram approach are determined by a global fit to measured branching fractions (external experimental inputs). These parameters are then inserted into the derived expressions to obtain numerical A_CP values. Because the input data are independent branching-fraction measurements and the central formulas are constructed from first-principles amplitudes plus mixing, the numerical results do not reduce to the inputs by definition or by self-citation. No load-bearing step matches any of the enumerated circularity patterns.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 0 invented entities

Central predictions rest on hadronic parameters fitted to branching fraction data and on standard assumptions about decay amplitudes and kaon mixing; no independent evidence for the fit parameters is supplied beyond the fit itself.

free parameters (1)
  • hadronic parameters in topological diagram approach
    Extracted by global fit to branching fractions and used to compute the CP asymmetries.
axioms (2)
  • domain assumption Topological diagram approach correctly parametrizes the hadronic matrix elements in D decays
    Invoked to perform the global fit that supplies the parameters for asymmetry calculations.
  • domain assumption Cabibbo-favored and doubly Cabibbo-suppressed amplitudes interfere as described by the Standard Model CKM structure
    Basis for the interference terms that generate the CP asymmetries when combined with kaon mixing.

pith-pipeline@v0.9.1-grok · 5879 in / 1252 out tokens · 44516 ms · 2026-06-30T20:19:25.940220+00:00 · methodology

discussion (0)

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Reference graph

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