Correlators are simpler than wavefunctions
Pith reviewed 2026-05-21 16:29 UTC · model grok-4.3
The pith
Correlators integrate Feynman propagators over full spacetime rather than the half-space used for wavefunctions, removing certain poles and forcing the first subleading Laurent coefficient to vanish at every pole.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The correlator is obtained by integrating Feynman propagators over the full spacetime, as opposed to the half-space for the wavefunction, which makes certain patterns of poles absent and produces a systematic Laurent expansion in which the first subleading term vanishes for every pole. There is an especially simple understanding of the expansion around the total energy pole up to second order, given by a differential operator acting on the amplitude. These results extend beyond single graphs to the full correlator in Tr φ³ theory.
What carries the argument
The difference in integration domain: full spacetime volume for the correlator versus past light-cone half-space for the wavefunction.
If this is right
- Certain families of poles that appear in wavefunction expressions are absent from the corresponding correlator.
- Correlators exhibit factorization properties in several kinematic limits that are not present for wavefunctions.
- Around every pole the Laurent expansion begins with a vanishing first correction term.
- The expansion around the total-energy pole up to second order is given by a differential operator acting directly on the amplitude.
- The same simplifications assemble into the complete correlator of Tr φ³ theory.
Where Pith is reading between the lines
- Direct correlator formulas could replace wavefunction intermediates in cosmological or scattering calculations that care only about equal-time observables.
- The vanishing subleading coefficient may generate new recursion or reduction identities that simplify higher-point computations.
- Similar domain-difference arguments might apply to other objects, such as form factors or matrix elements defined with different time contours.
Load-bearing premise
The wavefunction is defined strictly by integration over a half-space with no additional boundary or contour contributions that would change the pole structure or the vanishing of the subleading Laurent coefficient.
What would settle it
Compute the Laurent series of a concrete two- or three-point correlator and its wavefunction counterpart around a chosen pole and check whether the coefficient of the first subleading term is zero only in the correlator.
Figures
read the original abstract
Several recent works have revealed a simplicity in equal-time correlators that is absent in their wavefunction counterparts. In this letter, we show that this arises from the simple fact that the correlator is obtained by integrating Feynman propagators over the full spacetime, as opposed to the half-space for the wavefunction. Several striking new properties of correlators for any graph are made obvious from this picture. Certain patterns of poles that appear in the wavefunction do not appear in the correlator. The correlator also enjoys several remarkable factorization properties in various limits. Most strikingly, the correlator admits a systematic Laurent expansion in the neighborhood of every pole, with the first subleading term vanishing for every pole. There is an especially simple understanding of the expansion around the total energy pole up to second order, given by a differential operator acting on the amplitude. Finally, we show how these results extend beyond single graphs to the full correlator in Tr $\phi^3$ theory.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript claims that the simplicity of equal-time correlators relative to wavefunctions follows directly from integrating Feynman propagators over full spacetime rather than the half-space used for the wavefunction. This domain difference eliminates certain pole patterns, produces factorization properties, yields a systematic Laurent expansion around every pole with the first subleading term vanishing, provides a differential-operator representation around the total-energy pole, and extends to the full Tr φ³ correlator.
Significance. If the derivations hold, this provides a clear explanation for simplifications in correlators, potentially aiding calculations in QFT and cosmology. The factorization, Laurent expansion, and differential operator results are noteworthy strengths. The stress-test concern about hidden contour or boundary contributions does not land, as the full-spacetime integration with standard iε prescriptions is shown to be sufficient.
minor comments (2)
- The notation for poles in the wavefunction versus correlator could be made more explicit with a small table comparing the two.
- An explicit example of the differential operator acting on a simple amplitude would help verify the second-order expansion around the total-energy pole.
Simulated Author's Rebuttal
We thank the referee for their positive evaluation and recommendation of minor revision. The referee's summary accurately reflects the central thesis of our work: that the simplicity of equal-time correlators relative to wavefunctions originates from integrating Feynman propagators over full spacetime rather than the half-space relevant to the wavefunction. We appreciate the recognition of the resulting properties, including the absence of certain pole patterns, factorization behaviors, the systematic Laurent expansion with vanishing first subleading term at every pole, the differential-operator representation at the total-energy pole, and the extension to the complete Tr φ³ correlator. The referee's assessment that the stress-test concern regarding hidden contours or boundaries does not apply, given the standard iε prescriptions, aligns with our analysis.
read point-by-point responses
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Referee: The manuscript claims that the simplicity of equal-time correlators relative to wavefunctions follows directly from integrating Feynman propagators over full spacetime rather than the half-space used for the wavefunction. This domain difference eliminates certain pole patterns, produces factorization properties, yields a systematic Laurent expansion around every pole with the first subleading term vanishing, provides a differential-operator representation around the total-energy pole, and extends to the full Tr φ³ correlator.
Authors: We agree with the referee's concise summary of our results. The manuscript derives these features directly from the full-spacetime integration for arbitrary graphs, with explicit examples and proofs for the pole elimination, factorization in various limits, the vanishing subleading coefficient in the Laurent series around each pole, the differential operator acting on the amplitude up to second order at the total-energy pole, and the generalization to the full correlator in Tr φ³ theory. The standard iε prescription ensures no additional contour or boundary contributions arise, consistent with the referee's assessment. revision: no
Circularity Check
No significant circularity; derivation is self-contained from integration domains
full rationale
The paper's central claims follow directly from the explicit definitions of the wavefunction (half-space integral of propagators) versus the correlator (full-spacetime integral), using standard Feynman iε prescriptions. The absence of certain poles, vanishing of the first subleading Laurent coefficient, factorization properties, and differential-operator representation around the total-energy pole are obtained by direct residue evaluation in the full domain without additional boundary terms. No steps reduce by construction to fitted parameters, self-definitional loops, or load-bearing self-citations; the results are independent consequences of the domain difference and contour choices.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Feynman propagators are integrated over full spacetime for correlators and over half-space for wavefunctions
Forward citations
Cited by 2 Pith papers
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On the simplicity of de Sitter correlators
De Sitter correlators in conformally coupled φ³ theory admit a time-integral representation built from flat-space correlators, revealing intrinsic simplifications including vanishing of odd conjugate-momentum graphs a...
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de Sitter Wavefunction from Quadrangular Polylogarithms: Chain Graphs
The n-site chain graph contribution to the de Sitter cosmological wavefunction in conformally coupled φ³ theory is expressed explicitly in terms of Rudenko's quadrangular polylogarithms.
Reference graph
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discussion (0)
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