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arxiv: 2410.13362 · v3 · submitted 2024-10-17 · 🧮 math-ph · hep-th· math.MP· quant-ph

Further Evidence for Near-Tsirelson Bell-CHSH Violations in Quantum Field Theory via Haar Wavelets

Pith reviewed 2026-05-23 19:28 UTC · model grok-4.3

classification 🧮 math-ph hep-thmath.MPquant-ph
keywords Bell-CHSHTsirelson boundHaar waveletsquantum field theoryvacuum stateBell inequality violationswavelet integrals
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The pith

Bell-CHSH violations in quantum field theory can approach Tsirelson's bound if the maximal eigenvalues of Haar wavelet integral matrices approach π.

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

The paper investigates a construction based on bumpified Haar wavelets to generate explicit Bell-CHSH violations in the vacuum state of a (1+1)-dimensional massless spinor quantum field theory. It reduces the claim that these violations can get arbitrarily close to Tsirelson's bound to the mathematical question of whether the largest eigenvalue of certain symmetric matrices built from integrals of wavelet products tends to π in the limit of finer resolutions. The authors establish a lower bound of 3.11052 using a specific subclass of wavelets and present further numerical evidence supporting the general conjecture. If correct, this would mean that the standard vacuum already allows near-maximal quantum correlations in simple field theories. The result matters for understanding how much nonlocality is inherent in quantum field theory without special state preparation.

Core claim

The construction using bumpified Haar wavelets reduces the question of near-Tsirelson Bell-CHSH violations in the (1+1)D QFT vacuum to the conjecture that the asymptotic maximal eigenvalue of the sequence of symmetric matrices composed of integrals of Haar wavelet products approaches π; a subclass of wavelets achieves an eigenvalue of 3.11052, with additional numerical evidence provided for the conjecture.

What carries the argument

Symmetric matrices formed from integrals of products of bumpified Haar wavelets, whose maximal eigenvalue is conjectured to approach π in the continuum limit.

If this is right

  • Bell-CHSH violations can get arbitrarily close to Tsirelson's bound.
  • The vacuum state of massless spinor fields in (1+1)D Minkowski space permits strong Bell violations.
  • The wavelet construction provides an explicit way to realize near-maximal quantum correlations in QFT.
  • Numerical computations can test the approach to the bound by increasing matrix size.

Where Pith is reading between the lines

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

  • The conjecture, if true, might extend to other wavelet bases or field theories in different dimensions.
  • Reaching only 3.11052 suggests the convergence to π may be slow, requiring higher resolutions for closer approaches.
  • This could connect to broader questions about the maximal Bell violation achievable in relativistic quantum theories.

Load-bearing premise

The maximal eigenvalue of the symmetric matrices from Haar wavelet product integrals approaches π in the continuum limit.

What would settle it

A computation of the maximal eigenvalue for a sequence of increasingly large matrices that fails to increase toward π, for example remaining below 3.12 at very high resolution, would disprove the conjecture.

Figures

Figures reproduced from arXiv: 2410.13362 by David Dudal, Ken Vandermeersch.

Figure 1
Figure 1. Figure 1: The mother Haar wavelet ψ = ψ0,0. is satisfied and the linear span of {ψn,k}n,k∈Z is dense in L 2 (R). [17] The following symmetry property will be very useful to us. Lemma 3.2. For all n, k ∈ Z we have ψn,k(−x) = −ψn,−k−1(x) almost everywhere. Proof. We start by noting that the property holds for the mother Haar wavelet ψ = ψ0,0. Indeed, ψ0,0(−x) = ψ(−x) =    +1 if 0 ≤ −x < 1 2 −1 if 1 2 ≤ −x < 1 0 o… view at source ↗
Figure 2
Figure 2. Figure 2: The a.e. equality ψn,k(−x) = −ψn,−k−1(x), visually. that ψn,k(−x) = ( 2 n/2 ψ(2n (−x) − k) if − x ∈ In,k 0 otherwise = ( −2 n/2 ψ(2nx + k + 1) if x ∈ In,−k−1 0 otherwise = −ψn,−k−1(x) holds almost everywhere. See also [PITH_FULL_IMAGE:figures/full_fig_p007_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: The graph of the function J from the proof of Lemma 3.4. Proof. Let us rewrite the given integral by first integrating with respect to x: A(n,k),(m,ℓ) = − Z ψm,−ℓ(y) Z ψn,−k(x) x + y dx  dy. Then, for each y < 0 we can compute the inner integral as I(y) := Z ψn,−k(x) x + y dx = Z (−k+ 1 2 )2−n −k2−n +2n/2 x + y dx + Z (−k+1)2−n (−k+ 1 2 )2−n −2 n/2 x + y dx =2n/2 ln (−k + 1 2 )2−n + y −k2−n + y ! − 2 n/2… view at source ↗
Figure 4
Figure 4. Figure 4: Fig. 2 in [12]: Test function components for [PITH_FULL_IMAGE:figures/full_fig_p011_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: The test function components of f = (f1, f2) found in [12] satisfy the relation f2 = −cf1 quite closely. where d = (N1 − N0 + 1) × K. Then, the problem statement compactifies to (1 − c 2 ) X n,k,m,ℓ A(n,k),(m,ℓ) xn,k xm,ℓ = π √ 2η 1 + η 2 (6) −2c X n,k,m,ℓ A(n,k),(m,ℓ) xn,k xm,ℓ = − π √ 2η 1 + η 2 , (7) and the normality condition on f becomes the following normality condition on x: ∥x∥ 2 = 1/(1 + c 2 ). A… view at source ↗
Figure 6
Figure 6. Figure 6: Discrete plots for λmax A(N, 2) and λmax A(N, 5) , together with a compari￾son. 16 [PITH_FULL_IMAGE:figures/full_fig_p016_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: The terms an vanish relatively quickly. where the sequence a0, a1, a2, . . . is given by (see the proof of Lemma 3.4) an = A(0,1),(n,1) = −2 n/2 Z −2−n−1 −2−n J(y − 1) dy + 2n/2 Z 0 −2−n−1 J(y − 1) dy. The following closed form expression can be obtained: an = 2−n/2  2 n+1 − 2 n  ln(2) − 2 [PITH_FULL_IMAGE:figures/full_fig_p019_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: The first four functions fn(x) = 2 −n/2 (1 − x) x + 2n together with their linear upper bounds gn(x) = 2−3/2 (1 − x). Combining Lemmas 3.13 to 3.15, we find the following: Proposition 3.16. The asymptotic maximal eigenvalue approaches lim N→∞ λmax A(N, 1) = ln  1024 729  + 2α + 2(3 − 2 √ 2)X∞ n=1 ιn ≈ 3.1105202. Remark 3.17. This is already 3.11052/π = 99.01% of the way to π; but as could be expected, w… view at source ↗
Figure 9
Figure 9. Figure 9: The graphs of λmax F2(t)  and λmax F4(t)  . The graphs corresponding to different values of K are very similar. Let us define FK(t) as the K × K matrix valued Fourier series FK(t) = X∞ n=−∞ An(K)e int, t ∈ [0, 2π]. According to Theorem 3.19, we have the result lim N→∞ λmax A(N, K)  = max t∈[0,2π] λmax FK(t)  . The situation here is considerably more complex than the special case K = 1, as we now need t… view at source ↗
Figure 10
Figure 10. Figure 10: The basic Planck-taper window function s ε . 4.1 Bumpified Haar wavelets To construct smooth “bumpified” versions of the Haar wavelets (still compactly sup￾ported), following [10], the authors of [12] employ the Planck-taper window function. Definition 4.1. The basic Planck-taper window function with support on the interval [0, 1] is defined by s ε (x) =     1 + exp  ε(2x − ε) x(x − ε) −1… view at source ↗
Figure 11
Figure 11. Figure 11: The mother bumpified Haar wavelet σ ε = σ ε 0,0 . Definition 4.4 (Bumpified Haar wavelets). The mother bumpified Haar wavelet with support on [0, 1] is defined by σ ε (x) =    +s ε (2x) if 0 ≤ x < 1 2 −s ε (2x − 1) if 1 2 ≤ x < 1 0 otherwise. Bumpified versions of the Haar wavelets ψn,k may then be defined by σ ε n,k(x) = ( 2 n/2σ ε (2nx − k) if x ∈ In,k 0 otherwise. Analogously as in Proposition… view at source ↗
read the original abstract

This paper investigates a recent construction using bumpified Haar wavelets to demonstrate explicit violations of the Bell-Clauser-Horne-Shimony-Holt inequality within the vacuum state in quantum field theory. The construction was tested for massless spinor fields in $(1+1)$-dimensional Minkowski spacetime and is claimed to achieve violations arbitrarily close to an upper bound known as Tsirelson's bound. We show that this claim can be reduced to a mathematical conjecture involving the maximal eigenvalue of a sequence of symmetric matrices composed of integrals of Haar wavelet products. More precisely, the asymptotic eigenvalue of this sequence should approach $\pi$. We present a formal argument using a subclass of wavelets, allowing us to reach $3.11052$. Although a complete proof remains elusive, we present further compelling numerical evidence to support it.

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

2 major / 2 minor

Summary. The paper reduces the construction of near-Tsirelson Bell-CHSH violations in (1+1)-dimensional QFT vacuum states via bumpified Haar wavelets to an independent mathematical conjecture: that the largest eigenvalue λ_N of the N×N Gram matrices formed from integrals of products of these wavelets satisfies lim_{N→∞} λ_N = π. It supplies a rigorous lower bound λ ≥ 3.11052 for a restricted subclass of wavelets together with numerical diagonalization evidence for the full sequence.

Significance. If the eigenvalue conjecture holds, the work supplies concrete, falsifiable evidence that QFT can realize Bell-CHSH violations arbitrarily close to Tsirelson’s bound, a result of interest at the interface of quantum field theory and quantum information. The explicit mapping to an eigenvalue problem on Haar-wavelet Gram matrices, the analytic subclass bound, and the numerical checks constitute genuine strengths that render the physical claim testable without circularity or free parameters.

major comments (2)
  1. [Main text (conjecture statement and numerical section)] The central physical claim rests on the unproven limit lim λ_N = π. While the reduction itself is cleanly executed and the subclass argument (yielding 3.11052) is formal, the manuscript supplies neither an analytic proof of the full limit nor a rigorous error bound or convergence-rate estimate on the numerical extrapolation; this gap directly limits the strength of the “arbitrarily close” assertion.
  2. [Numerical results] The numerical evidence is reported only up to the subclass value 3.11052; the manuscript does not state the largest N for which the full matrices were diagonalized, the observed approach rate to π, or any extrapolation procedure, making it impossible to quantify how convincingly the numerics support the continuum limit.
minor comments (2)
  1. [Preliminaries] Notation for the bumpified Haar wavelets and the precise definition of the Gram-matrix entries ∫ ψ_i(x) ψ_j(x) dx should be collected in a single preliminary section for readability.
  2. [Numerical results] A short table comparing the subclass bound 3.11052, the numerical maxima, and π would help readers gauge the remaining gap.

Simulated Author's Rebuttal

2 responses · 1 unresolved

We thank the referee for the positive assessment of the reduction to the eigenvalue conjecture, the formal subclass bound, and the overall significance. We address the major comments point by point below.

read point-by-point responses
  1. Referee: [Main text (conjecture statement and numerical section)] The central physical claim rests on the unproven limit lim λ_N = π. While the reduction itself is cleanly executed and the subclass argument (yielding 3.11052) is formal, the manuscript supplies neither an analytic proof of the full limit nor a rigorous error bound or convergence-rate estimate on the numerical extrapolation; this gap directly limits the strength of the “arbitrarily close” assertion.

    Authors: We agree that the claim of violations arbitrarily close to Tsirelson’s bound is conditional on the unproven conjecture lim_{N→∞} λ_N = π. The manuscript already states explicitly that a complete analytic proof remains elusive and presents the subclass result of 3.11052 as a rigorous lower bound together with numerical evidence. We do not have an analytic proof of the full limit or rigorous error bounds on the numerical extrapolation. We will expand the numerical section with additional details on convergence behavior to better support the evidence presented. revision: partial

  2. Referee: [Numerical results] The numerical evidence is reported only up to the subclass value 3.11052; the manuscript does not state the largest N for which the full matrices were diagonalized, the observed approach rate to π, or any extrapolation procedure, making it impossible to quantify how convincingly the numerics support the continuum limit.

    Authors: We will revise the manuscript to state the largest N for which the full matrices were diagonalized, report the observed approach rate of λ_N toward π, and describe the extrapolation procedure. These additions will make the numerical support for the conjecture more transparent and quantifiable. revision: yes

standing simulated objections not resolved
  • Analytic proof of lim λ_N = π together with rigorous error bounds or convergence-rate estimates on the numerical extrapolation.

Circularity Check

0 steps flagged

No circularity detected; central claim is an explicit unproven conjecture on eigenvalue limits, supported by subclass proof and numerics without reduction to inputs by construction.

full rationale

The paper explicitly reduces the QFT Bell-CHSH claim to the mathematical conjecture that lim λ_N = π for the maximal eigenvalue of Gram matrices built from integrals of bumpified Haar wavelets. A formal lower bound of 3.11052 is proven for a restricted subclass, with the general limit supported by numerical diagonalization rather than any fitted parameter or self-referential definition. No step renames a known result, smuggles an ansatz via self-citation, or equates a 'prediction' to a fitted input. Self-citations to prior work (if present) are not load-bearing for the central conjecture, which is independently evidenced here. The derivation chain is transparent and self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The paper rests on standard properties of Haar wavelets and the definition of the QFT vacuum state; no free parameters, invented entities, or ad-hoc axioms are introduced beyond the central unproven conjecture itself.

axioms (2)
  • standard math Standard L2 properties and orthogonality relations of Haar wavelets and their bumpified versions
    Invoked when defining the matrix elements from wavelet products.
  • domain assumption The vacuum expectation values in massless (1+1)D spinor QFT can be expressed via the wavelet operators
    Required to translate the physical Bell operator into the wavelet matrix.

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Reference graph

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17 extracted references · 17 canonical work pages

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