arXiv subjects

Seiji Terashima

Publications and source records attributed to Seiji Terashima.

At least 19 recordsLinked to original sources

arXiv2026

Holography at Finite N: Breakdown of Bulk Reconstruction for Subregions

Within AdS/CFT, focusing on the AdS-Rindler wedge, we show that when $N$ is large but finite, correlation functions of reconstructed bulk operators grow exponentially with bulk momentum, overwhelming the usual $1/N$ suppression. The growth starts when the smeared operator's ultraviolet scale goes beyond a critical value $Λ_{crit} = \frac{2}π\ln N$, which is far below the Planck scale. Above this logarithmic threshold, the large $N$ expansion ceases to be reliable, and the would-be bulk operators cannot be consistently defined as observables in the full quantum gravity theory. Since the AdS-Rindler wedge describes the near-horizon region of black holes, this result implies a sharp $\ln N$ cutoff for reconstructing bulk operators across horizons. This has a direct impact on whether and how information from the black hole interior is encoded-a central question in the black hole information paradox.

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arXiv2026

Entanglement Wedge Reconstruction without Holographic Quantum Error Correction

Bulk reconstruction is a central problem in AdS/CFT, and entanglement wedge reconstruction is its subregion version. We argue that this subregion statement should be separated from the stronger holographic quantum error correction interpretation, in which one region-independent logical bulk operator has code-preserving representatives in several boundary regions. A simple locality argument shows that such a common reconstruction must commute with the code-preserving local algebras in the complementary regions. This is the mechanism realized in HaPPY-type codes: the erased regions are blind to a protected logical algebra. An ordinary finite $N$ holographic CFT does not have such a protected invisible sector for supergravity fields. Its low-energy local observables, in particular, suitably smeared stress tensors, detect the physical support and gravitational dressing of ordinary bulk operators, up to possible center or superselection data. Thus, there is no such holographic quantum error correction and the $N=\infty$ agreement of global and subregion HKLL formulae is a free-theory statement. What remains is entanglement wedge reconstruction without holographic quantum error correction, or subregion complementarity: each boundary region has its own code-preserving low-energy algebra and its own region-adapted bulk interpretation, rather than a shared logical operator.

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arXiv2026

Probing Black Hole Thermal Effects in the Dual CFT via Wave Packets

We investigate how the gravitational effects of a black hole manifest themselves as thermal behavior in the dual finite-temperature conformal field theory (CFT). In the holographic framework of AdS/CFT, we analyze a wave packet propagating into a black hole geometry in the bulk by computing three-point functions of a scalar primary operator in the boundary CFT. Our setup captures thermal signatures such as exponential damping of the expectation value, which are absent at zero-temperature. This provides a concrete and analytically tractable example of how black hole physics can be probed from the CFT side.

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arXiv2026

Finite N Black Holes through the Brick Wall

In AdS/CFT at finite N, black holes are described by ordinary quantum systems with finite entropy and discrete spectra, while semiclassical bulk effective field theory treats the near-horizon region as an ideal continuum. We reconsider the brick-wall model as a simple effective description of the finite N departure from the semiclassical near-horizon continuum in AdS/CFT. A Dirichlet wall is reflecting; however, once the regulated near-wall modes are replaced by interacting stretched-horizon degrees of freedom, the exterior simple sector can look absorptive and black-hole-like. If these degrees of freedom are thermally populated while the exterior incoming modes are in their vacuum, they radiate as an ordinary hot object, and this gives Hawking radiation. Furthermore, we show that finite N prevents the near-horizon sector from being an ideal continuum absorber; the brick-wall model is a simple effective representation of this limitation, where the failure of perfect absorption appears as residual reflection or echoes. Such return effects will not be suppressed as $e^{-S_{\rm BH}}$, although their detailed amplitude is model-dependent. We also discuss brick-wall-like models in which the effective inner boundary arises dynamically from a regular matter core rather than from an imposed boundary condition.

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arXiv2026

Subregion Complementarity in AdS/CFT

We examine the bulk reconstruction in the AdS/CFT correspondence. We demonstrate that the subregion duality fails to hold, highlighting discrepancies between operators in causal wedge reconstruction and those in global reconstruction at the leading order in the large $N$ limit. We argue the invalidity of the entanglement wedge reconstruction based on the holographic quantum error correction code, attributing it to non-perturbative finite $N$ effects or quantum gravity effects due to the trans-Planckian modes near the horizon. Nevertheless, we propose the subregion complementarity, illustrating that different CFT operators can describe a bulk subregion. While we expect that this complementarity is valid outside the horizon in general eternal black holes, it is inapplicable for single-sided black holes where a semi-classical description at the stretched horizon is absent.

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arXiv2026

Rindler Physics with a UV Cutoff on the Lattice

We investigate quantum field theory in Rindler space with a UV cutoff by considering a free scalar field on a lattice in Rindler coordinates. We find that the Minkowski vacuum is not exactly thermal with respect to the local lattice Rindler Hamiltonian. Nevertheless, for observables sufficiently far from the horizon, the Wightman function and the Unruh--DeWitt detector response reproduce the expected thermal behavior in the continuum limit. Thus, the Unruh effect survives operationally, even though exact thermality is lost at the state level. We also show that the Rindler vacuum energy density reproduces the standard continuum behavior away from the horizon, while the UV singularity at the horizon is replaced by a stretched-horizon contribution. Furthermore, the retarded Green function exhibits a component reflected at the stretched horizon, implying that an ingoing wave packet is reflected at a proper distance of order the cutoff. This provides an effective brick-wall picture in the UV-regulated theory. Our analysis suggests that, once a cutoff is introduced, the global Minkowski description and the wedge description based on a local Rindler Hamiltonian are no longer equivalent at the operator level.

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arXiv2025

Bulk Reconstruction and Gauge Invariance

In this paper, we discuss the concept of bulk reconstruction, which involves mapping bulk operators into CFT operators to understand the emergence of spacetime and gravity. We argue that the $N=\infty$ approximation fails to capture crucial aspects of gravity, as it does not respect gauge invariance and lacks direct connections between energy and boundary metrics. Key concepts such as entanglement wedge reconstruction and holographic error correction codes, which are based on the $N=\infty$ theory, may be incorrect or require significant revision when finite $N$ effects are considered. We present explicit examples demonstrating discrepancies in bulk reconstructions and suggest that a gauge-invariant approach is necessary for an accurate understanding.

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arXiv2025

Stretched Horizon Dissipation and the Fate of Echoes

We examine the dissipation of infalling particles near black holes under the assumption that the equivalence principle breaks down at the stretched horizon. This violation allows partial reflection of particles just outside the event horizon, as suggested by models such as the fuzzball and firewall proposals. We show that scattering with blue-shifted Hawking radiation leads to moderate dissipation when the particle energy is comparable to the Hawking temperature. The decay rate is independent of the Planck mass, and therefore gravitational wave echoes-arising from such partial reflection-may survive despite the presence of quantum gravitational effects. Our result is universal and does not rely on the detailed microphysics of the horizon.

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arXiv2025

Holographic Description of Bulk Wave Packets in AdS$_4$/CFT$_3$

In this paper, we extend the study of wave packets from the AdS$_3$/CFT$_2$ correspondence to AdS$_4$/CFT$_3$ and examine properties of their energy density. We find that, while the energy still localizes on the light cone, its spatial distribution exhibits momentum dependence and is no longer localized in higher dimensions. This result is significant as it reflects leading $1/N$ corrections to the generalized free field theory associated with the free bulk theory at $N=\infty$. Our findings are consistent with previous studies on entanglement wedge reconstruction including $1/N$ corrections, and also provide new insights into the structure of wave packets in higher-dimensional holography.

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arXiv2024

Wave Packets in AdS/CFT Correspondence

In this paper, we construct a general bulk wave packet in the AdS/CFT correspondence. This wave packet can be described both in bulk and CFT descriptions. Then, we compute the time evolution of the energy density of this wave packet state on the vacuum in the CFT picture of $AdS_3/CFT_2$. We find that the energy density of the wave packet is localized in two points, which means that the bulk wave packet corresponds to two light-like particle-like objects in the CFT picture. Our result implies that the entanglement wedge reconstruction given in [1] is invalid.

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arXiv2022

Rindler Bulk Reconstruction and Subregion Duality in AdS/CFT

In this paper, we study the AdS-Rindler reconstruction. The CFT operators naively given by the holographic dictionary for the AdS-Rindler reconstruction contain tachyonic modes, which are inconsistent with the causality and unitarity of the CFT. Therefore, the subregion duality and the entanglement wedge reconstruction do not hold. We also find that the tachyonic modes in the AdS-Rindler patch lead to arbitrary high-energy or trans-Planckian modes in the global AdS. It means that the mode expansion of the Rindler patch is sensitive to the UV limit of the theory, that is, quantum gravity. In addition, the tachyonic modes are related to the existence of null geodesics connecting the past and future horizons.

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arXiv2022

Simple Bulk Reconstruction in AdS/CFT Correspondence

In this paper, we show that the bulk reconstruction in the AdS/CFT correspondence is rather simple and has an intuitive picture, by showing that the HKLL bulk reconstruction formula can be simplified. We also reconstruct the wave packets in the bulk theory from the CFT primary operators. With these wave packets, we discuss the causality and duality constraints and find our picture is only the consistent one. Our picture of the bulk reconstruction can be applied to the asymptotic AdS spacetime.

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arXiv2022

On the Dynamics in the AdS/BCFT Correspondence

We consider a perturbation of the Einstein gravity with the Neumann boundary condition, which is regarded as an end of the world brane (ETW brane) of the AdS/BCFT correspondence, in the AdSd+1 spaectime where d is larger than 2. We obtain the mode expansion of the perturbations explicitly for the tensionless ETW brane case. We also show that the energy-momentum tensor in a d-dimensional BCFT should satisfy nontrivial constraints other than the ones for the boundary conformal symmetry if the BCFT can couple to a d-dimensional gravity with a specific boundary condition, which can be the Neumann or the conformally Dirichlet boundary conditions. We find these constraints are indeed satisfied for the free scalar BCFT. For the BCFT in the AdS/BCFT, we find that the BCFT can couple to the gravity with the Neumann boundary condition for the tensionless brane, but the BCFT can couple to the gravity with the conformally Dirichlet boundary condition for the nonzero tension brane by using holographic relations.

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arXiv2021

The colored Jones polynomials as vortex partition functions

We construct 3D $\mathcal{N}=2$ abelian gauge theories on $\mathbb{S}^2 \times \mathbb{S}^1$ labeled by knot diagrams whose K-theoretic vortex partition functions, each of which is a building block of twisted indices, give the colored Jones polynomials of knots in $\mathbb{S}^3$. The colored Jones polynomials are obtained as the Wilson loop expectation values along knots in $SU(2)$ Chern-Simons gauge theories on $\mathbb{S}^3$, and then our construction provides an explicit correspondence between 3D $\mathcal{N}=2$ abelian gauge theories and 3D $SU(2)$ Chern-Simons gauge theories. We verify, in particular, the applicability of our constructions to a class of tangle diagrams of 2-bridge knots with certain specific twists.

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arXiv2021

A Note on Commutation Relation in Conformal Field Theory

In this note, we explicitly compute the vacuum expectation value of the commutator of scalar fields in a d-dimensional conformal field theory on the cylinder. We find from explicit calculations that we need smearing not only in space but also in time to have finite commutators except for those of free scalar operators. Thus the equal time commutators of the scalar fields are not well-defined for a non-free conformal field theory, even if which is defined from the Lagrangian. We also have the commutator for a conformal field theory on Minkowski space, instead of the cylinder, by taking the small distance limit. For the conformal field theory on Minkowski space, the above statements are also applied.

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arXiv2020

Bulk Locality in AdS/CFT Correspondence

In this paper, we study the bulk local states in AdS/CFT correspondence in the large $N$ limit using the formula explicitly relating the bulk local operators and the CFT local operators. We identify the bulk local state in terms of CFT local states and find that the bulk local state corresponds to a CFT state supported in the whole space, which means a version of the subregion duality is not valid. On the other hand, CFT states supported in a space region are expressed in terms of the bulk states supported in a certain region. We find that the quantum error correction proposal is not realized although the puzzles of the radial locality which motivated the proposal are resolved in our analysis. For the understating of the bulk local states, an explicit realization of an analogue of the Reeh-Schlieder theorem plays an important role.

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arXiv2020

Classical Limit of Large N Gauge Theories with Conformal Symmetry

In this paper we study classical limit of conformal field theories realized by large N gauge theories using the generalized coherent states. For generic large N gauge theories with conformal symmetry, we show that the classical limit of them is described by the classical Einstein gravity. This may be regarded as a kind of derivation of the AdS/CFT correspondence.

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arXiv2018

Supersymmetry Breaking Phase in Three Dimensional Large N Gauge Theories

Three dimensional supersymmetric gauge theories are often in a gapped phase, in which SUSY is spontaneously broken, if all the matter fields are massive and decoupled in the low energy. We study this phase in the large $N$ limit using the localization technique for the theory on the ellipsoid, which interpolates the round three sphere and the flat space compactified on $S^1$. We find a large $N$ saddle point solution for the gauge theory with some massive matter fields. This solution gives a vanishing (generalized) Polyakov loop in the flat space limit, thus, it corresponds to the confining phase at the leading order in the $1/N$ expansion.

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