Hun Jang
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Hun Jang has a total of 13 co-authors. Here are the top co-authors by number of shared publications:
- Massimo Porrati
New York University
8 shared publications Byeongjun Yoon
Department of Physics and Engineering Physics, Yonsei University, Wonju, Republic of Korea
2 shared publicationsEun Bok
Institute of Advanced Machines and Design, Seoul National University, Seoul, Republic of Korea
2 shared publicationsHyeunwoo Kim
Department of Physics and Engineering Physics, Yonsei University, Wonju, Republic of Korea
2 shared publications- Jeong-Hyuck Park
Sogang University
2 shared publications - Minkyoo Kim
Sogang University
2 shared publications
Latest Publications
- Open Access
- 13 November 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (11)
Perturbative Nicolai-map diagrammatics: application to Poincaré supergravity
A bstract: We develop a perturbative, diagrammatic framework for constructing Nicolai maps and apply it to four-dimensional $$ \mathcal{N} $$ = 1 Poincaré supergravity expanded around flat Minkowski space. It provides an alternative to the coupling-flow-operator construction, which faces several obstructions when extended to local supersymmetry. Expanding the bosonic effective action and the Nicolai map jointly in the gravitational coupling κ and the loop-counting parameter ℏ, we derive the Nicolai-map defining conditions, i.e. the free-action and determinant-matching conditions, order by order. The diagrammatics enumerates all admissible local terms in the Nicolai-map ansatz from the effective-action diagrams and reduces the construction to a finite system of nonlinear polynomial equations. Carried through order κ 2 , the resulting constraints are found to be independent of the detailed bosonic input and hierarchical, order- κ 2 consistency further restricting the order- κ data. A consistent Nicolai-map construction for the Einstein-Hilbert graviton sector is found to require the Rarita-Schwinger gravitino already at this order: Einstein gravity admits a Nicolai map only through its $$ \mathcal{N} $$ = 1 supersymmetric completion, Poincaré supergravity, supporting Nicolai’s characterization of supersymmetry.- 13 November 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (11)
Open AccessPerturbative Nicolai-map diagrammatics: application to Poincaré supergravity
A bstract: We develop a perturbative, diagrammatic framework for constructing Nicolai maps and apply it to four-dimensional $$ \mathcal{N} $$ = 1 Poincaré supergravity expanded around flat Minkowski space. It provides an alternative to the coupling-flow-operator construction, which faces several obstructions when extended to local supersymmetry. Expanding the bosonic effective action and the Nicolai map jointly in the gravitational coupling κ and the loop-counting parameter ℏ, we derive the Nicolai-map defining conditions, i.e. the free-action and determinant-matching conditions, order by order. The diagrammatics enumerates all admissible local terms in the Nicolai-map ansatz from the effective-action diagrams and reduces the construction to a finite system of nonlinear polynomial equations. Carried through order κ 2 , the resulting constraints are found to be independent of the detailed bosonic input and hierarchical, order- κ 2 consistency further restricting the order- κ data. A consistent Nicolai-map construction for the Einstein-Hilbert graviton sector is found to require the Rarita-Schwinger gravitino already at this order: Einstein gravity admits a Nicolai map only through its $$ \mathcal{N} $$ = 1 supersymmetric completion, Poincaré supergravity, supporting Nicolai’s characterization of supersymmetry. - Open Access
- 23 September 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (9) , 231
Exact four-parameter rotating NS-NS vacuum in double field theory
A bstract: We construct an exact rotating vacuum of the NS-NS sector, equivalently a Double Field Theory vacuum. The construction applies compact SO (2) S-duality to a rotating Einstein-scalar seed. The solution has four independent parameters $$ \left\{\mathfrak{m},j,\mathfrak{q},\zeta \right\} $$ . 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 → 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 ℓ = 0 parametrized post-Newtonian data { MG , β PPN , γ PPN , h }. They give two inequivalent NS-NS geometries at identical monopole charges, with the degeneracy lifted at ℓ = 2. At the Kerr horizon locus the outer shell is generically singular in curvature. Above the threshold $$ \left|\mathfrak{q}\right|>\sqrt{{\mathfrak{m}}^2-{j}^2} $$ , 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 O ( D , D ) variables $$ \left\{d,{\mathcal{H}}_{AB}\right\} $$ remain well defined.- 23 September 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (9) , 231
Open AccessExact four-parameter rotating NS-NS vacuum in double field theory
A bstract: We construct an exact rotating vacuum of the NS-NS sector, equivalently a Double Field Theory vacuum. The construction applies compact SO (2) S-duality to a rotating Einstein-scalar seed. The solution has four independent parameters $$ \left\{\mathfrak{m},j,\mathfrak{q},\zeta \right\} $$ . 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 → 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 ℓ = 0 parametrized post-Newtonian data { MG , β PPN , γ PPN , h }. They give two inequivalent NS-NS geometries at identical monopole charges, with the degeneracy lifted at ℓ = 2. At the Kerr horizon locus the outer shell is generically singular in curvature. Above the threshold $$ \left|\mathfrak{q}\right|>\sqrt{{\mathfrak{m}}^2-{j}^2} $$ , 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 O ( D , D ) variables $$ \left\{d,{\mathcal{H}}_{AB}\right\} $$ remain well defined. - 1 September 2026
- Published by IOP Publishing in Journal of Cosmology and Astroparticle Physics
- Vol. 2026 (09)
Constraining spatial curvature with priors from swampland conjectures
We study a string-motivated theoretical prior on the quintessential dark energy model with exponential potential, V ( ϕ ) = V 0 e -λϕ , allowing for non-zero spatial curvature. First, we formulate the corresponding dynamical system and investigate its cosmological evolution numerically, illustrating the phase-space behaviour and the influence of curvature on the background dynamics. In open universes (Ω k > 0), it has been suggested that a curvature-related fixed point may support accelerated expansion even for relatively steep potentials compatible with swampland considerations. Next, we explicitly impose swampland-motivated priors on the slope parameter λ, restricting it to values consistent with the de Sitter conjecture that excludes the (curved) ΛCDM limit. Furthermore, we restrict our considerations to the range of field excursion that is consistent with the swampland distance conjecture. Our primary interest is the possibility that such theoretically-motivated priors may shift values of cosmological parameters inferred by observational data, compared with the standard analysis based on theory-agnostic priors such as a sufficiently wide flat prior. We examine this possibility using a combination of Planck CMB data, DESI BAO measurements, and recent Type Ia supernova samples, performing a Bayesian inference of the model parameters. Our analysis indicates that the swampland-motivated prior mildly shifts the values of Ω k .
- 1 September 2026
- Published by IOP Publishing in Journal of Cosmology and Astroparticle Physics
- Vol. 2026 (09)
Constraining spatial curvature with priors from swampland conjectures
We study a string-motivated theoretical prior on the quintessential dark energy model with exponential potential, V ( ϕ ) = V 0 e -λϕ , allowing for non-zero spatial curvature. First, we formulate the corresponding dynamical system and investigate its cosmological evolution numerically, illustrating the phase-space behaviour and the influence of curvature on the background dynamics. In open universes (Ω k > 0), it has been suggested that a curvature-related fixed point may support accelerated expansion even for relatively steep potentials compatible with swampland considerations. Next, we explicitly impose swampland-motivated priors on the slope parameter λ, restricting it to values consistent with the de Sitter conjecture that excludes the (curved) ΛCDM limit. Furthermore, we restrict our considerations to the range of field excursion that is consistent with the swampland distance conjecture. Our primary interest is the possibility that such theoretically-motivated priors may shift values of cosmological parameters inferred by observational data, compared with the standard analysis based on theory-agnostic priors such as a sufficiently wide flat prior. We examine this possibility using a combination of Planck CMB data, DESI BAO measurements, and recent Type Ia supernova samples, performing a Bayesian inference of the model parameters. Our analysis indicates that the swampland-motivated prior mildly shifts the values of Ω k .
- 16 March 2026
- Published by Springer Nature in Journal of the Korean Physical Society
- Vol. 88 (12) , 1325-1334
The QCD scale parameter from the photon structure function
- 16 March 2026
- Published by Springer Nature in Journal of the Korean Physical Society
- Vol. 88 (12) , 1325-1334
The QCD scale parameter from the photon structure function
- Open Access
- 4 December 2025
- Published by Springer Nature in Research Square
The QCD Scale Parameter from the Photon Structure Function
Photon structure function has been a solid platform in testing strong interaction along with nucleon structure function. Strong Interaction has the property that it is perturbatively calculable at high energy but becomes non-perturbative at low energy. This nature makes QCD hard to handle theoretically in factorizing these two regions. The fundamental dimensional parameter, so called the QCD scale parameter, $\lms$, is one of key players to factorize two energy regions. In this work, we extract the QCD scale parameter from the photon structure function by separating the perturbative QCD and non-perturbative QCD. In the process we use the vector dominance model for the non-perturbative energy region of the photon structure function.- 4 December 2025
- Published by Springer Nature in Research Square
Open AccessThe QCD Scale Parameter from the Photon Structure Function
Photon structure function has been a solid platform in testing strong interaction along with nucleon structure function. Strong Interaction has the property that it is perturbatively calculable at high energy but becomes non-perturbative at low energy. This nature makes QCD hard to handle theoretically in factorizing these two regions. The fundamental dimensional parameter, so called the QCD scale parameter, $\lms$, is one of key players to factorize two energy regions. In this work, we extract the QCD scale parameter from the photon structure function by separating the perturbative QCD and non-perturbative QCD. In the process we use the vector dominance model for the non-perturbative energy region of the photon structure function. - Open Access
- 23 August 2025
- Published by Elsevier in Physics Letters B
- Vol. 869
Traversable wormhole for string, but not for particle
- 23 August 2025
- Published by Elsevier in Physics Letters B
- Vol. 869
Open AccessTraversable wormhole for string, but not for particle
- Open Access
- 5 August 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (8) , 1-16
Supermassive gauginos in supergravity inflation with high-scale SUSY breaking
A bstract: A model of supergravity inflation we recently proposed can produce slow roll inflation and a realistic spectrum of particles even without F-term supersymmetry breaking. Supersymmetry is broken only by a D-term induced by a recently discovered new type of Fayet-Iliopoulos (FI) term. Almost all supersymmetric partners of the standard model fields can get masses as high as the inflationary Hubble scale. The exception is gauginos, for which the vanishing of F-terms implies an exact cancellation that keeps their masses exactly zero. To cure this problem without spoiling the simplicity of our model we introduce a new term that further enlarges the space of supergravity effective actions. It is an F-term that, similarly to the new FI term, becomes singular in the supersymmetric limit. We show that this term can produce large gaugino masses without altering the spectrum of other states and without lowering the cutoff of the effecive theory.
- 5 August 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (8) , 1-16
Open AccessSupermassive gauginos in supergravity inflation with high-scale SUSY breaking
A bstract: A model of supergravity inflation we recently proposed can produce slow roll inflation and a realistic spectrum of particles even without F-term supersymmetry breaking. Supersymmetry is broken only by a D-term induced by a recently discovered new type of Fayet-Iliopoulos (FI) term. Almost all supersymmetric partners of the standard model fields can get masses as high as the inflationary Hubble scale. The exception is gauginos, for which the vanishing of F-terms implies an exact cancellation that keeps their masses exactly zero. To cure this problem without spoiling the simplicity of our model we introduce a new term that further enlarges the space of supergravity effective actions. It is an F-term that, similarly to the new FI term, becomes singular in the supersymmetric limit. We show that this term can produce large gaugino masses without altering the spectrum of other states and without lowering the cutoff of the effecive theory.
- Open Access
Supermassive gauginos in supergravity inflation with high-scale SUSY breaking
A model of supergravity inflation we recently proposed can produce slow roll inflation and a realistic spectrum of particles even without F-term supersymmetry breaking. Supersymmetry is broken only by a D-term induced by a recently discovered new type of Fayet-Iliopoulos (FI) term. Almost all supersymmetric partners of the standard model fields can get masses as high as the inflationary Hubble scale. The exception is gauginos, for which the vanishing of F-terms implies an exact cancellation that keeps their masses exactly zero. To cure this problem without spoiling the simplicity of our model we introduce a new term that further enlarges the space of supergravity effective actions. It is an F-term that, similarly to the new FI term, becomes singular in the supersymmetric limit. We show that this term can produce large gaugino masses without altering the spectrum of other states and without lowering the cutoff of the effecive theory.
Open AccessSupermassive gauginos in supergravity inflation with high-scale SUSY breaking
A model of supergravity inflation we recently proposed can produce slow roll inflation and a realistic spectrum of particles even without F-term supersymmetry breaking. Supersymmetry is broken only by a D-term induced by a recently discovered new type of Fayet-Iliopoulos (FI) term. Almost all supersymmetric partners of the standard model fields can get masses as high as the inflationary Hubble scale. The exception is gauginos, for which the vanishing of F-terms implies an exact cancellation that keeps their masses exactly zero. To cure this problem without spoiling the simplicity of our model we introduce a new term that further enlarges the space of supergravity effective actions. It is an F-term that, similarly to the new FI term, becomes singular in the supersymmetric limit. We show that this term can produce large gaugino masses without altering the spectrum of other states and without lowering the cutoff of the effecive theory.
- Open Access
- 22 June 2023
- Published by Elsevier in Nuclear Physics B
- Vol. 993
Gauge theory on fiber bundle of hypercomplex algebras
- 22 June 2023
- Published by Elsevier in Nuclear Physics B
- Vol. 993
Open AccessGauge theory on fiber bundle of hypercomplex algebras
- Open Access
- 26 August 2022
- Published by American Physical Society (APS) in Physical Review D
- Vol. 106 (4) , 045024
Realization of slow-roll inflation and the MSSM in supergravity theories with new Fayet-Iliopoulos terms
A new supergravity D-term, not associated to gauged R-symmetry, was recently discovered and used to construct new supergravity models. In this paper we use a generalization of the new D-term that we used in previous works, to construct a supergravity model of slow-roll inflation with the observable sector of the minimal supersymmetric standard model. Supersymmetry is broken at a high scale in the hidden sector and communicated to the observable sector by gravity mediation. The new D-term contains free parameters that can give large masses to scalar superpartners of quarks and leptons and to the higgsinos while holding the masses of observed particles fixed. Gauginos receive a mass from a noncanonical kinetic term for the vector supermultiplets. We also present a simple argument proving in full generality that the cutoff of effective theories containing new D-terms can never exceed the supersymmetry breaking scale. In our theory, the relation between D-term and the Hubble constant during inflation also implies the universal relation .- 26 August 2022
- Published by American Physical Society (APS) in Physical Review D
- Vol. 106 (4) , 045024
Open AccessRealization of slow-roll inflation and the MSSM in supergravity theories with new Fayet-Iliopoulos terms
A new supergravity D-term, not associated to gauged R-symmetry, was recently discovered and used to construct new supergravity models. In this paper we use a generalization of the new D-term that we used in previous works, to construct a supergravity model of slow-roll inflation with the observable sector of the minimal supersymmetric standard model. Supersymmetry is broken at a high scale in the hidden sector and communicated to the observable sector by gravity mediation. The new D-term contains free parameters that can give large masses to scalar superpartners of quarks and leptons and to the higgsinos while holding the masses of observed particles fixed. Gauginos receive a mass from a noncanonical kinetic term for the vector supermultiplets. We also present a simple argument proving in full generality that the cutoff of effective theories containing new D-terms can never exceed the supersymmetry breaking scale. In our theory, the relation between D-term and the Hubble constant during inflation also implies the universal relation .