arXiv subjects

Dmitry S. Ageev

Publications and source records attributed to Dmitry S. Ageev.

At least 19 recordsLinked to original sources

arXiv2026

Flat holography for spinor fields

We develop an asymptotic-coefficient construction for a free Dirac field in four-dimensional Minkowski spacetime using hyperbolic Milne slicing. We solve the massive mode equation and restrict the boundary source--response analysis to the massless sector. Decomposition into harmonics on three-dimensional hyperbolic space, labeled by a continuous principal-series parameter, yields a separated-point nonlocal kernel up to the action normalization and local contact terms. The kernel has the universal form required by two-dimensional conformal covariance for spin-$\tfrac12$ principal-series primaries. We identify the independent boundary spinor component, retain the two neutrally labeled Milne phases $τ^{\mp i ν}$, and construct regular source-normalized wavefunctions with conformal-primary covariance in planar and global representations of the celestial sphere $S^2$. A full CCFT interpretation still requires finite-cutoff renormalization, the complementary barred-response pairing, a global identification of the phase sectors with $\mathcal I^\pm$, and matching to the standard energy-Mellin scattering basis.

hep-th↗

arXiv2026

Higher-dimensional chaotic features and random matrix signatures following a local quench

We study the multidimensional erratic structure of correlation functions produced by local operator quenches in finite-volume free massive scalar field theory in dimensions 2 and 3. The basic observable is the subtracted equal-time two-point function in the locally excited state and its spatiotemporal patterns of extrema. We analyze these extrema by the multidimensional diagnostics recently introduced for chaotic scattering amplitudes and related problems: all-pair distance distributions, nearest-neighbor spacings, greedy-path spacing ratios, and the extrema form factor. For the $1+1$-dimensional local quench we find that, in the regime of small Euclidean smearing, the fitted extremum statistics move close to the $β=1$ random-matrix benchmark, while increasing the smearing scale softens the effective repulsion and moves the distributions away from the GOE-like value. For the $2+1$-dimensional local quench we find that the nearest-neighbor statistics of the refined extrema are close to, or above, the $β=1$ benchmark, and the greedy-path ratio statistics are described by even larger effective $β$ values. Finally we studied the all-pair extrema spatial form factor and found that, in the one-, two-, and three-dimensional cases, its main structure is controlled by the corresponding uniform interval, rectangle, or cuboid geometry of the extrema cloud and found the dip-ram-plateau structure in the last two cases. Thus the form factor provides a complementary global diagnostic of how the extrema fill their effective metric support, while the genuinely nontrivial local and mesoscopic organization is carried by the nearest-neighbor and greedy-path statistics.

hep-th↗

arXiv2026

The Schrodinger Equation as a Gauge Theory

In this paper, we formulate the Schrodinger equation in gauge-theoretic terms. Starting from the Madelung representation, we rewrite the conserved probability current using gauge fields, namely a one-form gauge field in the $(2+1)$-dimensional theory and a two-form gauge field in the $(3+1)$-dimensional theory. This gives a local equivalence between the Schrodinger equation, quantum hydrodynamics and a non-relativistic gauge theory, while the global information is carried by the quantization condition of phase winding around zeros of the wavefunction. We then use this correspondence to study how topological deformations of gauge action and symmetry properties are represented in the wavefunction and fluid descriptions. On the gauge side, BF couplings to additional one-forms account for electromagnetic coupling, Berry connections, spinor dynamics, adiabatic non-abelian Berry connections, and intrinsic holonomy. Chern-Simons term admit, after eliminating the gauge field, a nonlocal realization in terms of wavefunction. This functional retain the topological content of the gauge description, but also contain dynamical contribution. In the presence of boundaries, the topological terms produce edge degrees of freedom and boundary charge algebras. Finally, in the nonlinear regime with a Bogoliubov sound mode, the dual two-form description relates acoustic memory to large gauge transformations and identifies the soft sector expected to complete the corresponding infrared triangle.

hep-th↗

arXiv2026

Random matrix theory signatures in free field theory

We show that, within a finite window of parameter space, random matrix theory (RMT) statistics emerge in observables of a finite-volume massive free scalar field theory after a local operator quench. The spacing-ratio distribution of two-point-function extremum locations is close to the Gaussian orthogonal ensemble statistics. An extrema-based form factor exhibits a dip--ramp--plateau structure characteristic of RMT. By contrast, the standard spectral form factor shows no ramp, consistent with the underlying free spectrum, while a global quench yields qualitatively different statistics.

hep-th↗

arXiv2026

Entanglement islands, fuzzballs and stretched horizons

We study the implementation of the island prescription in fuzzball-inspired models of black holes. As a simplified setup, we model a fuzzball by replacing the event horizon with a reflecting boundary (stretched horizon). In the framework of two-dimensional model with such boundary, we analyze the dynamics of entanglement entropy. We find that the presence of the boundary modifies the behavior of the island saddle, and for a range of parameter values we observe the effect of blinking island found in arXiv:2311.16244 which inevitably leads to the analogue of information paradox. We then extend the analysis to higher dimensions, incorporating both bulk and boundary contributions to the generalized entropy. The existence of island solutions is found to depend sensitively on the boundary conditions and the position of the stretched horizon, naturally leading to the absence of entanglement islands for a wide range of parameters. Finally, we consider more "realistic" stringy fuzzball geometries, including superstrata and bubbling solutions, and estimate whether island solutions can arise in these backgrounds. The results indicate that the existence of islands depends on the behavior of the geometric area near the cap, and is not guaranteed in general.

hep-th↗

arXiv2026

Disparity in sound speeds: implications for elastic unitarity and the effective potential in quantum field theory theory

We study interacting scalar field theories in which different fields propagate with inequivalent spatial kinetic tensors, corresponding to different sound speeds in different directions. We derive the exact elastic two-body unitarity relation and show that the phase space defines a positive kernel on the sphere, so that the scattering amplitude acts as an operator in angular-momentum space. The corresponding unitarity bounds constrain the eigenvalues of the phase-space-rescaled amplitude. In the weak-anisotropy regime, we obtain the leading correction explicitly and show that it induces $s-d$ mixing. For a two-scalar quartic model, we verify the anisotropic optical theorem at one loop and derive coupled channel elastic unitarity bounds. We also compute the local one-loop effective potential and analyze the corresponding one-loop renormalization-group structure. In the classically scale-invariant limit, the Gildener-Weinberg flat direction is unchanged, whereas anisotropy modifies the radiatively generated scalon mass. In the isotropic but unequal-velocity limit, several results become analytic and the RG flow exhibits an additional invariant ray.

hep-th↗

arXiv2026

Neural Network Quantum Field Theory from Transformer Architectures

We propose a neural-network construction of Euclidean scalar quantum field theories from transformer attention heads, defining $n$-point correlators by averaging over random network parameters in the NN-QFT framework. For a single attention head, shared random softmax weights couple different width coordinates and induce non-Gaussian field statistics that persist in the infinite-width limit $d_k\to\infty$. We compute the two-point function in an attention-weight representation and show how Euclidean-invariant kernels can be engineered via random-feature token embeddings. We then analyze the connected four-point function and identify an "independence-breaking" contribution, expressible as a covariance over query-key weights, which remains finite at infinite width. Finally, we show that summing many independent heads with standard $1/N_h$ normalization suppresses connected non-Gaussian correlators as $1/N_h$, yielding a Gaussian NN-QFT in the large-head limit.

cs.LG↗

arXiv2026

Excited String States and D-branes from Infinite Width Neural Networks

We explore recent proposal to represent worldsheet string path integrals by integrating over parameters of a wide random-feature neural network whose output is identified with the embedding field $X^μ$. In this paper we extend it focusing on scattering with excited states insertions and for worldsheets with boundaries introducing fixed-feature Gaussian normal-ordering prescription for derivative composites (removing the neural contact term at finite width), and propose realization of mixed Neumann/Dirichlet boundary conditions interpreted as a neural D$p$-brane. As concrete outputs, we derive the sphere four-point integrand with a single $(1,1)$ insertion and the disk four-tachyon amplitude on a D$p$-brane, recovering the expected derivative prefactors, boundary exponents, and momentum-conservation limits after renormalization.

hep-th↗

arXiv2026

One-Loop Renormalization of Anisotropic Two-Scalar Quantum Field Theories

We develop a basis--covariant one--loop renormalization framework for two interacting real scalars in $D=4-ε$ with the most general two--derivative Lorentz--violating quadratic form, allowing anisotropic spatial gradients and direction--dependent kinetic mixing, together with general cubic and quartic interactions forming RG complete set of operators at one-loop. In dimensional regularization with minimal subtraction we compute the full set of one--loop UV divergences and obtain closed beta functions for quartic and cubic couplings, masses. The pole coefficients admit a universal spectral representation as angular averages over the direction--dependent eigenvalues and projectors of the UV kinetic matrix; all anisotropy dependence enters through a single universal kernel admitting two--particle phase--space interpretation. We classify fixed points and fixed manifolds and show, in particular, that anisotropy restricts the existence of the coupled Wilson--Fisher--type fixed point. When the cross--gradients are turned on the coefficients in beta functions are governed by six phase--space weights admitting interpretation in terms of encoding ``populations'' and ``coherences'' of the UV normal modes.

hep-th↗

arXiv2025

From Confinement to Chaos in AdS/CFT Correspondence via Non-equilibrium Local States

In this paper, we study excited states in Anti-de Sitter (AdS) space prepared by local operator insertions of a massive scalar field, corresponding to local operator quenches in a free bulk scalar theory. Using the AdS/CFT correspondence, we compute the time evolution of boundary observables in the dual CFT states. We then introduce a hard wall in AdS Poincare coordinates to impose an infrared cutoff (hard-wall), creating a confining deformation of the dual conformal field theory, and analyze the dynamics of excited states in this confining background. By comparing the evolution of boundary two-point correlation functions in the deformed theory to the statistics of Gaussian random matrix ensembles, we show that for sufficiently heavy operators, the spacing-ratio statistics of peaks in temporal dynamics are closest to those of the Gaussian Symplectic Ensemble (GSE). Finally, we extend the analysis to the compact BTZ black hole and to its hard-wall deformation, finding qualitatively similar trends.

hep-th↗

arXiv2025

Butterfly velocity and chaos suppression in de Sitter space

In this note, we study the holographic CFT in the de Sitter static patch at finite temperature $T$ and chemical potential. We find that butterfly velocity $v_B$ in such field theory degenerates for all values of the Hubble parameter $H$ and $T$. We interpret this as a chaos disruption caused by the interplay between the expansion of chaotic correlations constrained by $v_B$ and effects caused by de Sitter curvature. The chemical potential restores healthy butterfly velocity for some range of temperatures. Also, we provide some analogy of this chaos suppression with the Schwinger effect in de Sitter and black hole formation from shock wave collision.

hep-th↗

arXiv2025

Spectral form factors for curved spacetimes with horizon

The spectral form factor is believed to exhibit a special type of behavior called ``dip-ramp-plateau'' in chaotic quantum systems that originates from random matrix theory. This suggests that the shape of the spectral form factor could serve as an indicator of chaos in various quantum systems. It has been shown recently that the dip-ramp-plateau structure appears in the spectral form factor when the normal modes of a massless scalar field theory in the brick-wall model of the BTZ black hole are treated as eigenvalues of a quantum Hamiltonian. At the same time, the level spacing distribution of these normal modes differs from that associated with random matrix theory ensembles. In this paper, we extend the results for BTZ background to the case of non-zero mass of the field, study the generalized spectral form-factor, and consider the same context for another non-trivial background -- de Sitter space. We compare the generalized spectral form factor for simple integrable quantum systems and for backgrounds with a horizon to the behavior predicted by random matrix theory. As a result, we confirm that BTZ and de Sitter brick-wall models are highly distinct integrable systems that exhibit the dip-ramp-plateau structure of the SFF but differ in the structure of the three-level generalized spectral form factor from the one predicted by random matrix theory. This raises the question on whether the DRP structure is an indicator of what is known as quantum chaos.

hep-th↗

arXiv2024

Black Holes, Cavities and Blinking Islands

Placing a black hole in a cavity provides a natural framework for exploring gravitational scales, thermodynamic instabilities, and effective gravity theories. In this paper, we examine the evolution of entanglement entropy and entanglement islands in a two-sided extension of the Schwarzschild black hole in a cavity. By introducing a reflecting boundary in the eternal black hole exteriors, we regulate the infrared modes of Hawking radiation, finding that the entanglement entropy eventually saturates at a constant value. This value can be lower than the black hole thermodynamic entropy, thus avoiding the Page formulation of the information paradox. Regarding entanglement islands, we identify a universal effect induced by the boundary, which we term the ``blinking island'' -- where the entanglement island temporarily disappears, resulting in a short-time information paradox.

hep-th↗

arXiv2024

Local quenches in fracton field theory: Lieb-Robinson bound, non-causal dynamics and fractal excitation patterns

We study the out-of-equilibrium dynamics induced by a local perturbation in fracton field theory. For the ${\mathbb Z}_4$ and ${\mathbb Z}_8$-symmetric free fractonic theories, we compute the time dynamics of several observables such as the two-point Green function, $\langle ϕ^2 \rangle$ condensate, energy density, and the dipole momentum. The time-dependent considerations highlight that the free fractonic theory breaks causality and exhibits instantaneous signal propagation, even if an additional relativistic term is included to enforce a speed limit in the system. We show that it is related to the fact that the Lieb-Robinson bound does not hold in the continuum limit of the fracton field theory, and the effective bounded speed of light does not emerge. For the theory in finite volume, we show that the fracton wave front acquires fractal shape with non-trivial Hausdorff dimension, and argue that this phenomenon cannot be explained by a simple self-interference effect.

hep-th↗

arXiv2023

Quantum quenches in fractonic field theories

We study out-of-equilibrium dynamics caused by global quantum quenches in fractonic scalar field theories. We consider several types of quenches, in particular, the mass quench in theories with different types of discrete rotational symmetries ($\mathbb{Z}_4$ and $\mathbb{Z}_8$), as well as an instantaneous quench via the transition between them. We also investigate fractonic boundary quenches, where the initial state is prepared on a finite-width slab in Euclidean time. We find that perturbing a fractonic system in finite volume especially highlights the restricted mobility via the formation and subsequent evolution of specific $\mathbb{Z}_4$-symmetric spatial structures. We discuss a generalization to $\mathbb{Z}_n$-symmetric field theories, and introduce a proper regularization, which allows us to explicitly deal with divergences inherent to fractonic field theories.

hep-th↗

arXiv2023

Unveiling Topological Modes on Curved Surfaces

In this paper, we investigate topological modes of different physical systems defined on arbitrary two-dimensional curved surfaces. We consider the shallow water equations, inhomogeneous Maxwell's equations, Jackiw-Rebbi model and show how the topological protection mechanism responses to the presence of curvature in different situations. We show the existence of a line gap in the considered models and study the condition on the curve which can host topological modes.

cond-mat.mes-hall↗

arXiv2023

From locality to irregularity: Introducing local quenches in massive scalar field theory

In this paper, we initiate the study of operator local quenches in non-conformal field theories. We consider the dynamics of excited local states in massive scalar field theory in an arbitrary spacetime dimension and generalize the well-known two-dimensional CFT results. We derive the energy density, $U(1)$-charge density and $ϕ^2(x)$-condensate post-quench dynamics, and identify different regimes of their evolution depending on the values of the field mass and the quench regularization parameter. For local quenches in higher-dimensional free massless scalar theories, we reproduce the structure of the available holographic results. We also investigate the local quenches in massive scalar field theory on a cylinder and show that they cause an erratic and chaotic-like evolution of observables with a complicated localization/delocalization pattern.

hep-th↗

arXiv2022

Exploring uberholography

In this paper, we study the holographic quantum error correcting code properties in different boundary fractal-like structures. We construct and explore different examples of the uberholographic bulk reconstruction corresponding to these structures in higher dimensions for Cantor-like sets, thermal states and $T\overline{T}$-deformed conformal field theories. We show how the growth of the system dimension emphasizes the role of the Cantor set, due to the special bound naturally arising in this context.

hep-th↗