arxiv: 2604.14508 · v1 · submitted 2026-04-16 · ✦ hep-th

Recognition: unknown

Fermionic modes of D-instanton wormholes from broken local supersymmetry

H. Itoyama , Hikaru Kawai , Shoichi Kawamoto

Authors on Pith no claims yet

Pith reviewed 2026-05-10 11:13 UTC · model grok-4.3

classification ✦ hep-th

keywords D-instanton wormholestype IIB superstringbroken local supersymmetryfermionic modescurrent-current two-point functionstree-level cylinderBPS amplitude

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The pith

Modes of broken local supersymmetry in D-instanton wormholes produce the fermionic modes observed on their boundaries.

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

The paper studies D-instanton wormholes in type IIB superstring theory within the low-energy supergravity framework. It calculates two-point functions and finds that the axio-dilaton correlator vanishes as expected for a BPS state detected by two D-instantons, but other scalar correlators do not vanish. This non-vanishing behavior is then used to argue that supersymmetry-breaking modes in the bulk can induce fermionic modes on the boundaries. The induction occurs through a deformation involving current-current two-point functions that propagate along the tree-level cylinder connecting the boundaries. The treatment extends naturally to configurations with multiple D-instantons and to other Euclidean branes.

Core claim

In low-energy supergravity treatment of type IIB superstring on general D-instanton wormhole profiles in the bulk, non-vanishing scalar two-point functions are obtained in addition to the vanishing ⟨τ* τ*⟩ that corresponds to the BPS amplitude detected by two D-instantons at their respective boundaries. This is exploited to show that the modes of broken local supersymmetry in the bulk deliver the fermionic (diagonal) modes on the boundaries through the deformation by the form of current-current two point functions propagating on the tree level cylinder geometry.

What carries the argument

Deformation by current-current two-point functions propagating on the tree-level cylinder geometry from broken local supersymmetry modes in the bulk to fermionic boundary modes.

Load-bearing premise

The low-energy supergravity treatment remains valid for arbitrary D-instanton wormhole profiles and the tree-level cylinder geometry accurately captures the propagation of the current-current two-point functions.

What would settle it

A calculation of the fermionic two-point functions on the boundaries in a concrete D-instanton wormhole that fails to match the deformation from the bulk current-current functions would disprove the claim.

read the original abstract

In low-energy supergravity treatment of type IIB superstring on general D-instanton wormhole profiles in the bulk, we obtain non-vanishing scalar two-point functions in addition to the vanishing $\langle \tau^* \tau^* \rangle$ that corresponds to the BPS amplitude detected by two D-instantons at their respective boundaries. This is exploited to show that the modes of broken local supersymmetry in the bulk deliver the fermionic (diagonal) modes on the boundaries through the deformation by the form of current-current two point functions propagating on the tree level cylinder geometry. Our treatment is generalizable to multi D-instanton cases and general Euclidean branes.

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.

Desk Editor's Note private letter to a colleague

The paper links bulk broken SUSY to boundary fermions in D-instanton wormholes using cylinder 2pt functions, but the geometry approximation is a potential weak point.

read the letter

The main thing to know is that this paper argues the modes from broken local supersymmetry in the bulk of D-instanton wormholes deliver fermionic diagonal modes on the boundaries. They do this by deforming the setup with current-current two-point functions that propagate on the tree-level cylinder geometry. Along the way they find non-vanishing scalar two-point functions, unlike the vanishing one for the BPS case with two D-instantons. What the paper does well is apply the low-energy supergravity approximation to general D-instanton wormhole profiles in type IIB string theory. This leads to a treatment that they say extends naturally to multiple D-instantons and other Euclidean branes. The connection they draw between bulk and boundary through these correlators is a concrete step beyond just stating the wormhole backgrounds. The soft spot sits in the geometry assumption. The stress-test note points out that general wormhole profiles warp the metric away from a pure cylinder due to instanton backreaction. The current-current propagators then need to be computed on that deformed space, not the tree-level cylinder. The abstract asserts the result for general profiles but fixes the propagation to the cylinder form without showing why higher corrections can be ignored in the fermionic sector. If the full text has explicit checks or limits where this holds, that would strengthen it, but as stated it looks like the part that could be sensitive. This kind of work is for people focused on non-perturbative string theory, Euclidean quantum gravity, and supersymmetry breaking mechanisms. A reader looking at wormhole effects or D-instanton contributions to amplitudes might pick up ideas from the proposed link. The paper engages honestly with the setup and literature on these topics, even if the evidence for the approximation is thin so far. It is worth sending to a serious referee who can examine the two-point function derivations and the validity of the cylinder approximation in detail. I recommend putting it through peer review.

Referee Report

1 major / 1 minor

Summary. The manuscript presents a low-energy supergravity analysis of type IIB string theory on general D-instanton wormhole profiles in the bulk. It reports obtaining non-vanishing scalar two-point functions in addition to the vanishing ⟨τ* τ*⟩ correlator that corresponds to the BPS amplitude detected by two D-instantons at their boundaries. The authors argue that modes of broken local supersymmetry in the bulk deliver the fermionic (diagonal) modes on the boundaries through deformation by current-current two-point functions propagating on the tree-level cylinder geometry. The treatment is claimed to be generalizable to multi D-instanton cases and general Euclidean branes.

Significance. If the derivations hold and the cylinder approximation is justified, the result would link bulk broken local supersymmetry to boundary fermionic modes in Euclidean wormhole geometries via current-current correlators, offering a potential mechanism for understanding non-perturbative effects and SUSY breaking in string theory. The claimed generality across arbitrary profiles and multi-instanton extensions could have implications for holographic dualities or instanton contributions, though the abstract provides no explicit equations, limits, or checks to assess impact.

major comments (1)

[Abstract] Abstract: The central claim requires that broken local SUSY modes deliver boundary fermionic modes specifically via deformation by current-current two-point functions on the tree-level cylinder geometry. For general D-instanton wormhole profiles the Euclidean metric deviates from a pure cylinder due to instanton-induced warping and possible backreaction, so the propagator must be solved on the deformed background. The low-energy supergravity treatment is invoked without an explicit demonstration that higher-order metric fluctuations or profile-dependent corrections remain negligible for the diagonal fermionic sector; this assumption is load-bearing for the generality asserted in the abstract.

minor comments (1)

[Abstract] The abstract refers to 'fermionic (diagonal) modes' and 'scalar two-point functions' without defining the precise operators or the meaning of 'diagonal' in the boundary context; a brief clarification in the introduction would improve readability.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading of the manuscript and for highlighting the importance of justifying the cylinder approximation in the low-energy supergravity analysis. We address the major comment below.

read point-by-point responses

Referee: [Abstract] Abstract: The central claim requires that broken local SUSY modes deliver boundary fermionic modes specifically via deformation by current-current two-point functions on the tree-level cylinder geometry. For general D-instanton wormhole profiles the Euclidean metric deviates from a pure cylinder due to instanton-induced warping and possible backreaction, so the propagator must be solved on the deformed background. The low-energy supergravity treatment is invoked without an explicit demonstration that higher-order metric fluctuations or profile-dependent corrections remain negligible for the diagonal fermionic sector; this assumption is load-bearing for the generality asserted in the abstract.

Authors: We agree that general D-instanton wormhole profiles induce warping and backreaction, so the full metric is not a pure cylinder. Our derivation nevertheless evaluates the leading tree-level current-current two-point function on the cylinder background because this geometry encodes the dominant contribution from the broken local supersymmetry modes to the diagonal fermionic boundary correlators. In the low-energy supergravity regime, profile-dependent corrections and higher-order metric fluctuations enter only at subleading orders and do not alter the vanishing of the BPS amplitude or the non-vanishing scalar two-point functions that source the fermionic modes. We will add a short paragraph in the revised manuscript that explicitly states this suppression argument and clarifies the regime of validity, thereby supporting the claimed generality. revision: partial

Circularity Check

0 steps flagged

No significant circularity; derivation uses independent 2pt function calculation on stated geometry

full rationale

The paper's chain starts from low-energy supergravity on general D-instanton wormhole profiles, computes non-vanishing scalar two-point functions (distinct from the vanishing BPS one), and then deforms via current-current 2pt functions on the tree-level cylinder to obtain boundary fermionic modes from bulk broken SUSY modes. This is a forward derivation from the computed correlators rather than a self-definition or a fitted parameter renamed as prediction. The cylinder is explicitly labeled 'tree level' and the treatment is stated as an approximation valid in the low-energy regime; no equation reduces the final fermionic modes to the input geometry by construction. Generalization to multi-instanton cases is asserted without load-bearing self-citation chains or uniqueness theorems imported from the same authors. The central claim therefore retains independent content from the explicit 2pt function evaluation.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

Review is abstract-only, so ledger is minimal and based solely on stated treatment; full paper would likely contain additional domain assumptions typical of supergravity.

axioms (2)

domain assumption Low-energy supergravity approximation is valid for general D-instanton wormhole profiles
Explicitly invoked in the abstract as the framework used.
domain assumption Tree-level cylinder geometry captures the propagation of current-current two-point functions
Stated as the geometry on which the functions propagate.

pith-pipeline@v0.9.0 · 5412 in / 1343 out tokens · 64426 ms · 2026-05-10T11:13:23.473908+00:00 · methodology

discussion (0)

Reference graph

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