arXiv subjects

Seolhwa Kim

Publications and source records attributed to Seolhwa Kim.

6 recordsLinked to original sources

arXiv2026

Enhanced Correlations in Hawking Radiation from Near-Extremal Collapse

We consider the formation of a near-extremal Reissner-Nordstrom black hole by collapse, and show how to compute correlations in the outgoing Hawking radiation due to enhanced gravitational backreaction effects in the near-horizon region. This is done by reducing to the s-wave and employing the Hamiltonian formulation of Einstein-Maxwell theory coupled to a scalar field. Solving the constraints yields an action for the scalar field that incorporates gravitational backreaction effects at the quantum level, governed by an effective coupling g = G/(πr_0^3 T_H) that grows at low temperature, as in recent Schwarzian-based analyses. This action produces corrections to the free field Hawking state which are imprinted on correlation functions of the Hawking radiation measured at null infinity. As part of our analysis, we show that this action evaluated in the AdS_2 region is equivalent, at the level of all tree-level boundary correlators, to the standard JT/Schwarzian description coupled to dressed bilocal operators. We also reproduce some one-loop results. In our approach, metric fluctuations are included quantum mechanically through the reduced scalar action, rather than through a semiclassical expectation value, and our computation of the radiation manifestly reduces to Hawking's original treatment when metric fluctuations are neglected.

hep-th↗

arXiv2025

Higher structure of non-invertible symmetries from Lagrangian descriptions

The symmetry structure of a quantum field theory is determined not only by the topological defects that implement the symmetry and their fusion rules, but also by the topological networks they can form, which is referred to as the higher structure of the symmetry. In this paper, we consider theories with non-invertible symmetries that have an explicit Lagrangian description, and use it to study their higher structure. Starting with the 2d free compact boson theory and its non-invertible duality defects, we will find Lagrangian descriptions of networks of defects and use them to recover all the $F$-symbols of the familiar Tambara-Yamagami fusion category $\operatorname{TY}(\mathbb{Z}_N,+1)$. We will then use the same approach in 4d Maxwell theory to compute $F$-symbols associated with its non-invertible duality and triality defects, which are 2d topological field theories. In addition, we will also compute some of the $F$-symbols using a different (group theoretical) approach that is not based on the Lagrangian description, and find that they take the expected form.

hep-th↗

arXiv2025

Codimension one defects in free scalar field theory

We study various aspects of codimension one defects in free scalar field theory, with particular emphasis on line defects in two-dimensions. These defects are generically non-conformal, but include conformal and topological defects as special cases. Our analysis is based on the interplay between two complementary descriptions, the first involving matching conditions imposed on fields and their derivatives across the defect, and the second on the resummation of perturbation theory in terms of renormalized defect couplings. Using either description as appropriate we compute a variety of observables: correlators of fields in the presence of such defects; the defect anomalous dimension; multiple defects and their fusion; canonical quantization and instabilities; ring shaped defects with application to the g-theorem and the entanglement entropy of accelerating defects; defects on the torus and Cardy formulas for the asymptotic density of states of the defect Hilbert space; and quenches produced by spacelike defects. The simplicity of the model allows for explicit computation of all these quantities, and provides a starting point for more complicated theories involving interactions.

hep-th↗

arXiv2024

S-Matrix Path Integral Approach to Symmetries and Soft Theorems

We explore a formulation of the S-matrix in terms of the path integral with specified asymptotic data, as originally proposed by Arefeva, Faddeev, and Slavnov. In the tree approximation the S-matrix is equal to the exponential of the classical action evaluated on-shell. This formulation is well-suited to questions involving asymptotic symmetries, as it avoids reference to non-gauge/diffeomorphism invariant bulk correlators or sources at intermediate stages. We show that the soft photon theorem, originally derived by Weinberg and more recently connected to asymptotic symmetries by Strominger and collaborators, follows rather simply from invariance of the action under large gauge transformations applied to the asymptotic data. We also show that this formalism allows for efficient computation of the S-matrix in curved spacetime, including particle production due to a time dependent metric.

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arXiv2023

Systematics of Boundary Actions in Gauge Theory and Gravity

We undertake a general study of the boundary (or edge) modes that arise in gauge and gravitational theories defined on a space with boundary, either asymptotic or at finite distance, focusing on efficient techniques for computing the corresponding boundary action. Such actions capture all the dynamics of the system that are implied by its asymptotic symmetry group, such as correlation functions of the corresponding conserved currents. Working in the covariant phase space formalism, we develop a collection of approaches for isolating the boundary modes and their dynamics, and illustrate with various examples, notably AdS$_3$ gravity (with and without a gravitational Chern-Simons terms) subject to assorted boundary conditions.

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arXiv2019

Constraining Affleck-Dine Leptogenesis after Thermal Inflation

Affleck-Dine leptogenesis after thermal inflation along the $LH_u$ direction requires $m_L^2+m_{H_u}^2 < 0$ up to the AD scale ($|L|\simeq |H_u|\sim 10^9$ GeV). We renormalised this condition from the AD scale to the soft supersymmetry breaking scale by solving the renormalisation group equations perturbatively in the Yukawa couplings to obtain a semi-analytic constraint on the soft supersymmetry breaking parameters. We also used a fully numerical method to renormalise the baryogenesis condition and constrained the Minimal Supersymmetric Cosmological Model using the resulting baryogenesis condition and other constraints, specifically, electroweak symmetry breaking, the observed Higgs mass, and the axino dark matter abundance.

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