arXiv subjects

Jeong-Hyuck Park

Publications and source records attributed to Jeong-Hyuck Park.

At least 19 recordsLinked to original sources

arXiv2026

Exact Four-Parameter Rotating NS--NS Vacuum in Double Field Theory

We construct an exact rotating vacuum of the NS--NS sector, equivalently a Double Field Theory vacuum. The construction applies compact $\mathbf{SO}(2)$ S-duality to a rotating Einstein--scalar seed. The solution has four independent parameters $\{\mathfrak{m},j,\mathfrak{q},ζ\}$. To our knowledge, this is the first explicit rotating solution of the pure NS--NS vacuum equations with all three NS--NS fields $\{g,B,ϕ\}$ determined analytically, independent dilaton and $H$-flux charges, and no Maxwell sector. The static limit is obtained by taking the rotation parameter $j\to 0$. In this limit the geometry is not the spherical Burgess--Myers--Quevedo solution. Instead, it is an axial Zipoy--Voorhees branch carrying $H$-flux, so an oblate deformation remains after rotation is switched off. This geometric memory is absent in pure general relativity and in Einstein--Maxwell--dilaton--axion. The two static branches nevertheless share the same $\ell=0$ parametrized post-Newtonian data $\{MG,β_{\mathrm{PPN}},γ_{\mathrm{PPN}},h\}$. They give two inequivalent NS--NS geometries at identical monopole charges, with the degeneracy lifted at $\ell=2$. At the Kerr horizon locus the outer shell is generically singular in curvature. Above the threshold $|\mathfrak{q}|>\sqrt{\mathfrak{m}^{2}-j^{2}}$, polar geodesics are repelled outward and the rotation axis becomes regular in curvature at the shell. On that axis the inverse metric $g^{μν}$ stays finite while the lower-index Riemannian metric components diverge, whereas off the axis the inverse metric itself diverges. This axis-local degeneracy may offer a setting for non-Riemannian geometry in Double Field Theory, where $g_{μν}$ is not fundamental and the $\mathbf{O}(D,D)$ variables $\{d,\mathcal{H}_{AB}\}$ remain well defined.

hep-th↗

arXiv2026

Attractive statistical forces and Pauli crystal formation in trapped Fermi gases

Exchange statistics endows identical particles with an effective "statistical potential", whose familiar exact form is two-body and purely repulsive for fermions. Here we construct an exact collective many-body form: the thermodynamics of $N$ trapped ideal fermions maps onto classical distinguishable particles governed by a single potential -- exactly for harmonic confinement at all temperatures, and to leading semiclassical order for arbitrary potentials. The associated force separates canonically into pairwise contributions, which for $N\geq 3$ can turn attractive, governed by a simple geometric criterion. Classical minimization reproduces observed few-body Pauli-crystal symmetries and agrees with the $N=55$ ground-state probability maximum at sub-percent shell accuracy. Heating drives discrete structural transitions accompanied by a crossover of the strongest force from attractive to repulsive. Both the potential and its forces are directly computable from existing single-shot imaging data, turning quantum exchange into measurable classical mechanics.

cond-mat.stat-mech↗

arXiv2026

Empirical confirmation of bosonic wealth statistics in Bitcoin UTXOs

Digitalisation transforms money from distinguishable physical objects into fungible informational units. A recent theoretical framework predicts that such indistinguishable wealth obeys bosonic occupancy statistics, leading to geometric ownership distributions and enhanced inequality. Using Bitcoin blockchain data, we test this prediction on 63 UTXO denominations across 72 monthly snapshots (2018--2023). A one-parameter geometric model describes the ownership distributions, reproducing both mean holdings and their temporal evolution; Jensen--Shannon divergence values lie below $0.08$ in $99.74\%$ of cases. The inferred inverse-temperature parameter satisfies the analytic mean--temperature relation to better than $0.1\%$ in every sample -- a self-consistency test that two-parameter alternatives cannot pass -- and remains within a narrow band across eight orders of magnitude in denomination and over six years. Bitcoin UTXO ownership statistics are therefore consistent with bosonic occupancy laws, suggesting that the informational nature of electronic money may act as a structural driver of inequality in digital economies.

physics.soc-ph↗

arXiv2025

Universal Box Operator: $\mathbf{O}(D,D)$-Symmetry and $α^{\prime}$-Corrections

We construct a fully covariant,$\mathbf{O}(D,D)$-symmetric d'Alembertian -- or box operator -- that acts on tensor fields of arbitrary rank and provides a universal kinetic term for all bosonic closed-string states. In its Riemannian parametrization, the operator packages the Riemann curvature, $H$-flux, and dilaton gradient into a single duality-covariant object. This yields $\mathbf{O}(D,D)$-symmetric gravitational-wave equations for the massless sector, governs the tachyon and all massive modes, and clarifies how higher excitations contribute to $α^{\prime}$-corrections. The box operator thus supplies a unified description of closed-string dynamics across the entire spectrum. Our analysis shows that any apparent breaking of $\mathbf{O}(D,D)$ symmetry arises only after integrating out massive modes in a Wilsonian sense, where loop momentum integrals obscure half of the doubled momenta. We stand on the view that $\mathbf{O}(D,D)$ symmetry and doubled diffeomorphisms remain exact and undeformed at the fundamental level of string theory.

hep-th↗

arXiv2025

Gravitational Core of Double Field Theory: Lecture Notes

Double Field Theory (DFT) has emerged as a comprehensive framework for gravity, presenting a testable and robust alternative to General Relativity (GR), rooted in the $\mathbf{O}(D,D)$ symmetry principle of string theory. These lecture notes aim to provide an accessible introduction to DFT, structured in a manner similar to traditional GR courses. Key topics include doubled-yet-gauged coordinates, Riemannian versus non-Riemannian parametrisations of fundamental fields, covariant derivatives, curvatures, and the $\mathbf{O}(D,D)$-symmetric augmentation of the Einstein field equation, identified as the unified field equation for the closed string massless sector. By offering a novel perspective, DFT addresses unresolved questions in GR and enables the exploration of diverse physical phenomena, paving the way for significant future research.

gr-qc↗

arXiv2025

Traversable wormhole for string, but not for particle

We propose a Lorentzian wormhole geometry characterized by a closed string massless sector with nontrivial $H$-flux and a scalar dilaton. In the string frame, the dilaton exhibits a negative kinetic term, enabling the existence of the wormhole. The geometry consists of three distinct regions. The middle region contains the throat, and its boundaries with the other two regions form non-Riemannian two-spheres, where a fundamental string becomes chiral, akin to a non-relativistic string. While point-particle geodesics are complete within each region and non-traversable across regions, strings perceive the geometry differently, allowing a chiral string to traverse freely.

hep-th↗

arXiv2024

Late-time Cosmology without Dark Sector but with Closed String Massless Sector

We explore the possibility of solving the dark energy and the coincidence problems by postulating the massless sector of closed strings. This sector constitutes the gravitational multiplet of string theory and, when applied to four-dimensional cosmology, predicts that \textit{the expansion of an open Universe defined in string frame is readily accelerating}. We confront the prediction with the late-time cosmological data of Type Ia supernovae and quasar absorption spectrum, which probe the evolutions of the Hubble parameter and possibly the fine-structure constant. We report that these observations are in admirable agreement with the prediction without any dark sector or coincidence problem. We estimate the Hubble constant, $H_{0}\simeq 71.2\pm 0.2\,\mathrm{km/s/Mpc}$.

hep-th↗

arXiv2023

Distinguishable Cash, Bosonic Bitcoin, and Fermionic Non-fungible Token

Modern technology has brought novel types of wealth. In contrast to hard cashes, digital currencies do not have a physical form. They exist in electronic forms only. Yet, it has not been clear what impacts their ongoing growth will make, if any, on wealth distribution. Here we propose to identify all forms of contemporary wealth into two classes: 'distinguishable' or 'identical'. Traditional tangible moneys are all distinguishable. Financial assets and cryptocurrencies, such as bank deposits and Bitcoin, are boson-like, while non-fungible tokens are fermion-like. We derive their ownership-based distributions in a unified manner. Each class follows essentially the Poisson or the geometric distribution. We contrast their distinct features such as Gini coefficients. Further, aggregating different kinds of wealth corresponds to a weighted convolution where the number of banks matters and Bitcoin follows Bose-Einstein distribution. Our proposal opens a new avenue to understand the deepened inequality in modern economy, which is based on the statistical physics property of wealth rather than the individual ability of owners. We call for verifications with real data.

econ.GN↗

arXiv2022

Fractons, non-Riemannian Geometry, and Double Field Theory

We initiate a systematic study of fracton physics within the geometric framework of Double Field Theory. We ascribe the immobility and large degeneracy of the former to the non-Riemannian backgrounds of the latter, in terms of generalised geodesics and infinite-dimensional isometries. A doubled pure Yang-Mills or Maxwell theory reduces to an ordinary one coupled to a strain tensor of elasticity theory, and thus rather remarkably provides a unifying description of photons and phonons. Upon a general Double Field Theory background, which consists of Riemannian and non-Riemannian subspaces, the dual photon-phonon pair becomes fractonic over the non-Riemannian subspace. When the elasticity displacement vector condenses, minimally coupled charged particles acquire an effective mass even in the purely Riemannian case, yielding predictions for polaron physics and time crystals. Furthermore, the immobility of neutral particles along the non-Riemannian directions is lifted to a saturation velocity for charged particles. Utilising the differential geometry of Double Field Theory we also present curved spacetime extensions which exhibit general covariance.

hep-th↗

arXiv2022

Post-Newtonian Feasibility of the Closed String Massless Sector

We perform post Newtonian analysis of Double Field Theory as a test of string theory in gravitational sector against observations. We identify the Eddington--Robertson--Schiff parameters $β_{\rm{PPN}}$, $γ_{\rm{PPN}}$ with the charges of electric $H$-flux and dilaton respectively, and further relate them to stress-energy tensor. We show ${β_{\rm{PPN}}=1}$ from weak energy condition and argue that the observation of $γ_{\rm{PPN}}\simeq 1$ signifies the ultrarelativistic equation of state in baryons, or the suppression of gluon condensate.

hep-th↗

arXiv2022

Lecture note on Clifford algebra

This lecture note surveys the gamma matrices in general dimensions with arbitrary signatures, the study of which is essential to understand the supersymmetry in the corresponding spacetime. The contents supplement the lecture presented by the author at Modave Summer School in Mathematical Physics, Belgium, June, 2005.

hep-th↗

arXiv2022

Janus van der Waals equations for real molecules with two-sided phase transitions

We obtain families of generalised van der Waals equations characterised by an even number $n=2,4,6$ and a continuous free parameter which is tunable for a critical compressibility factor. Each equation features two adjacent critical points which have a common critical temperature $T_{c}$ and arbitrarily close two critical densities. The critical phase transitions are naturally two-sided: the critical exponents are $α_{\scriptscriptstyle{P}}=γ_{\scriptscriptstyle{P}}=\frac{2}{3}$, $β_{\scriptscriptstyle{P}}=δ^{-1}=\frac{1}{3}$ for $T>T_{c}$ and $α_{\scriptscriptstyle{P}}=γ_{\scriptscriptstyle{P}}=\frac{n}{n+1}$, $β_{\scriptscriptstyle{P}}=δ^{-1}=\frac{1}{n+1}$ for $T<T_{c}$. In contrast with the original van der Waals equation, our novel equations all reduce consistently to the classical ideal gas law in low density limit. We test our formulas against NIST data for eleven major molecules and show agreements better than the original van der Waals equation, not only near to the critical points but also in low density regions.

physics.chem-ph↗

arXiv2021

Identifying Riemannian singularities with regular non-Riemannian geometry

Admitting non-Riemannian geometries, Double Field Theory extends the notion of spacetime beyond the Riemannian paradigm. We identify a class of singular spacetimes known in General Relativity with regular non-Riemannian geometries. The former divergences merely correspond to coordinate singularities of the generalised metric for the latter. Computed in string frame, they feature an impenetrable non-Riemannian sphere outside of which geodesics are complete with no singular deviation. Approaching the non-Riemannian points, particles freeze and strings become (anti-)chiral.

hep-th↗

arXiv2021

Non-Riemannian isometries from double field theory

We explore the notion of isometries in non-Riemannian geometries. Such geometries include and generalise the backgrounds of non-relativistic string theory, and they can be naturally described using the formalism of double field theory. Adopting this approach, we first solve the corresponding Killing equations for constant flat non-Riemannian backgrounds and show that they admit an infinite-dimensional algebra of isometries which includes a particular type of supertranslations. These symmetries correspond to known worldsheet Noether symmetries of the Gomis-Ooguri non-relativistic string, which we now interpret as isometries of its non-Riemannian doubled background. We further consider the extension to supersymmetric double field theory and show that the corresponding Killing spinors can depend arbitrarily on the non-Riemannian directions, leading to "supersupersymmetries" that square to supertranslations.

hep-th↗

arXiv2020

String Theory and non-Riemannian Geometry

The $\mathbf{O}(D,D)$ covariant generalized metric, postulated as a truly fundamental variable, can describe novel geometries where the notion of Riemannian metric ceases to exist. Here we quantize a closed string upon such backgrounds and identify flat, anomaly-free, non-Riemannian string vacua in the familiar critical dimension, $D{=26}$ (or $D{=10}$). Remarkably, the whole BRST closed string spectrum is restricted to just one level with no tachyon, and matches the linearized equations of motion of Double Field Theory. Taken as an internal space, our non-Riemannian vacua may open up novel avenues alternative to traditional string compactification.

hep-th↗

arXiv2020

$\mathbf{O}(D,D)$ completion of the Friedmann equations

In string theory the closed-string massless NS-NS sector forms a multiplet of $\mathbf{O}(D,D)$ symmetry. This suggests a specific modification to General Relativity in which the entire NS-NS sector is promoted to stringy graviton fields. Imposing off-shell $\mathbf{O}(D,D)$ symmetry fixes the correct couplings to other matter fields and the Einstein field equations are enriched to comprise $D^{2}+1$ components, dubbed recently as the Einstein Double Field Equations. Here we explore the cosmological implications of this framework. We derive the most general homogeneous and isotropic ansatzes for both stringy graviton fields and the $\mathbf{O}(D,D)$-covariant energy-momentum tensor. Crucially, the former admits space-filling magnetic $H$-flux. Substituting them into the Einstein Double Field Equations, we obtain the $\mathbf{O}(D,D)$ completion of the Friedmann equations along with a generalized continuity equation. We discuss how solutions in this framework may be characterized by two equation-of-state parameters, $w$ and $λ$, where the latter characterizes the relative intensities of scalar and tensor forces. When $λ+3w=1$, the dilaton remains constant throughout the cosmological evolution, and one recovers the standard Friedmann equations for generic matter content (i.e. for any $w$). We further point out that, in contrast to General Relativity, neither an $\mathbf{O}(D,D)$-symmetric cosmological constant nor a scalar field with positive energy density gives rise to a de Sitter solution.

hep-th↗

arXiv2020

Stringy Newton Gravity with $H$-flux

A Symmetry Principle has been shown to augment unambiguously the Einstein Field Equations, promoting the whole closed-string massless NS-NS sector to stringy graviton fields. Here we consider its weak field approximation, take a non-relativistic limit, and derive the stringy augmentation of Newton Gravity: \[ \begin{array}{lll} {\bf{\nabla}^{2}Φ}=4πG ρ+\bf{H}{\bf{\cdot}}\bf{H}\,, \quad&\qquad\bf{\nabla}\bf{\cdot}\bf{H}=0\,, \quad&\qquad {\bf{\nabla}\bf{\times}\bf{H}}=4πG\, \bf{K}\,. \end{array} \] Not only the mass density $ρ$ but also the current density $\mathbf{K}$ is intrinsic to matter. Sourcing $\mathbf{H}$ which is of NS-NS $H$-flux origin, $\mathbf{K}$ is nontrivial if the matter is `stringy'. $\mathbf{H}$ contributes quadratically to the Newton potential, but otherwise is decoupled from the point particle dynamics, i.e. $\bf{\ddot{x}}=-\bf{\nabla}Φ$. We define `stringization' analogous to magnetization and discuss regular as well as monopole-like singular solutions.

hep-th↗

arXiv2020

A note on Faddeev--Popov action for doubled-yet-gauged particle and graded Poisson geometry

The section condition of Double Field Theory has been argued to mean that doubled coordinates are gauged: a gauge orbit represents a single physical point. In this note, we consider a doubled and at the same time gauged particle action, and show that its BRST formulation including Faddeev--Popov ghosts matches with the graded Poisson geometry that has been recently used to describe the symmetries of Double Field Theory. Besides, by requiring target spacetime diffeomorphisms at the quantum level, we derive quantum corrections to the classical action involving dilaton, which might be comparable with the Fradkin--Tseytlin term on string worldsheet.

hep-th↗