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Soon-Tae Hong

Publications and source records attributed to Soon-Tae Hong.

At least 37 records · Page 2Linked to original sources

Local free-fall temperatures of charged BTZ black holes in massive gravity

We obtain a (3+3)-dimensional global flat embedding of the generalized (2+1) charged Bañados-Teitelboim-Zanelli black holes in massive gravity. We also study the local free-fall temperatures for freely falling observers starting from rest and investigate the effect of the charge and graviton mass in free-fall temperatures.

gr-qc↗

Global embeddings and hydrodynamic properties of Kerr black hole

In the presence of a rotating Kerr black hole, we investigate hydrodynamics of the massive particles and massless photons, to construct relations among number density, pressure and internal energy density of the massive particles and photons around the rotating Kerr black hole and to study an accretion onto the black hole. On equatorial plane of the Kerr black hole, we investigate the bound orbits of the massive particles and photons around the black hole to produce their radial, azimuthal and precession frequencies. With these frequencies we study the black holes GRO~J1655-40 and 4U~1543-47, to explicitly obtain the radial, azimuthal and precession frequencies of the massive particles in the flow of perfect fluid. We next consider the massive particles in the stable circular orbit of radius of $1.0~ly$ around the supernovas SN 1979C, SN 1987A and SN 2213-1745 in the Kerr curved spacetime, and around the potential supermassive Schwarzschild black holes M87, NGC 3115, NGC 4594, NGC 3377, NGC 4258, M31, M32 and Galatic center, to estimate their radial and azimuthal frequencies, which are shown to be the same results as those in no precession motion. The photon unstable orbit is also discussed in terms of the impact parameter of the photon trajectory. Finally, on the equatorial plane of the Kerr black hole, we construct the global flat embedding structures possessing (9+3) dimensionalities outside and inside the event horizon of the rotating Kerr black hole. Moreover, on the plane we investigate the warp products of the Kerr spacetime.

gr-qc↗

Higher dimensional flat embedding of Taub-NUT-AdS spacetime

We construct a global flat embedding structure of a Taub-NUT-AdS spacetime to yield a (6+5)-dimensional novel global embedding Minkowski spacetime. We also investigate Taub-NUT, Schwarzschild-AdS and Schwarzschild limits of the global embedding by exploiting parameter reduction scheme. In particular, we observe in the vanishing monopole strength limit of the Taub-NUT-AdS that the parameter reduction is not smoothly applicable to the Schwarzschild-AdS, due to the presence of imaginary roots of its lapse function associated with event horizon. Moreover, reductions from the Taub-NUT-AdS and Schwarzschild-AdS to Taub-NUT and Schwarzschild, respectively, are successfully performed. Finally, we construct the global embedding Minkowski spacetimes for the patches inside the event horizons of the Taub-NUT-AdS and its extended manifolds.

gr-qc↗

Free fall temperature of Schwarzschild-Tangherlini-AdS black hole

Investigating five-dimensional Schwarzschild-Tangherlini-AdS black hole, we construct a (6+2)-dimensional flat embedding structure. Exploiting this flat manifold, we evaluate a free fall temperature of the black hole in manifold ranging from outer event horizon to the infinity.

physics.gen-ph↗

De Rham Cohomology of $CP^{1}$ model with Hopf term

We investigate the $CP^{1}$ model possessing the Hopf term which respects the second class constraints and admits the well defined the BRST operator $Q$. Using the operator $Q$, we explicitly construct its de Rham cohomology group by deriving the ensuing quotient group via both the collections of all $Q$-closed and $Q$-exact ghost number $p$-forms. Moreover, we study the $CP^{1}$ model without the Hopf term to evaluate the ensuing effect of the Hopf term on the cohomology group. We find that the Hopf term effects on the de Rham cohomology originate from the Hilbert space modified by this Hopf term.

hep-th↗

SU(3) group structure of strange flavor hadrons

We provide the isoscalar factors of the SU(3) Clebsch-Gordan series 8x35 which are extensions of the previous works of de Swart, McNamee and Chilton and play practical roles in current ongoing strange flavor hadron physics research. To this end, we pedagogically study the SU(3) Lie algebra, its spin symmetries, and its eigenvalues for irreducible representations. We also evaluate the values of the Wigner D functions related to the isoscalar factors; these functions are immediately applicable to strange flavor hadron phenomenology. Exploiting these SU(3) group properties associated with the spin symmetries, we investigate the decuplet-to-octet transition magnetic moments and the baryon octet and decuplet magnetic moments in the flavor symmetric limit to construct the Coleman-Glashow-type sum rules.

hep-ph↗

Kaluza-Klein mass spectra on extended dimensional branes

We study the hierarchy problem on the four- and five-branes which are constructed by attaching a circle and a sphere to the standard three-brane, respectively. The effective masses in their excited spectra on these extended dimensional branes imply intriguing characteristics associated with the quantization of the compact circular and spherical manifolds. In particular, their lightest effective masses are shown to suppress exponentially with respective to the Planck mass, similar to the three-brane case. We also investigate the effective couplings in these extended dimensional branes.

hep-ph↗

Warp products and (2+1) dimensional spacetimes

We investigate the geometrical aspects of the extended (2+1) dimensional Banados-Teitelboim-Zanelli spacetimes in the multiply warped product scheme. To do this, we analyze the interior physical properties by constructing the explicit warp functions in these regions.

gr-qc↗

Interior properties of five-dimensional Schwarzschild black hole

We investigate inner structure of Schwarzschild black hole on a five-dimensional spacetime S^3xR^2. To do this, we exploit a fünfbein scheme. In particular, we construct an equation of state of hydrostatic equilibrium for the five-dimensional Schwarzschild black hole, which is a five-dimensional version of the Tolman-Oppenheimer-Volkoff equation on four-dimensional manifold. We also investigate uniform density interior configuration of the five-dimensional black hole which consists of incompressible fluid of density, to find a general relativistic expression for pressure.

gr-qc↗

Geometrical and hydrodynamic aspects of five-dimensional Schwarzschild black hole

Exploiting the five-dimensional Schwarzschild black hole, we study the geometrical natures of the higher dimensional black hole to yield the (6+1) dimensional global embedding Minkowski space structure. We next obtain the Hawking temperature on this five-dimensional manifold, whose result is different from the four-dimensional one. On the contrary, the radial component of the Einstein equation for the massive particles or photons on the five-dimensional spacetime is shown to have the same form as the four-dimensional black hole one. Moreover, we construct the effective potential on equatorial plane of the restricted three-brane to investigate the behavior of the particles or photons on this restricted brane.

gr-qc↗

Dynamics of stringy congruence in early universe

We studied the singularity of the geodesic surface congruence for timelike and null strings using the expansion of the universe in the string theory. We had Raychaudhuri type equation for the expansion. Assuming the stringy strong energy condition and initial convergence, we induced the existence of singularity and got the same inequality equation of the string strong energy condition for both timelike and null stringy congruence. In this paper we want to study the twist and shear aspects of the stingy geodesic surface congruence. Under some natural conditions we derive the equations of the twist and the shear in terms of the expansion of the universe. In appendix we investigate the geodesic surface congruence of the null strings.

gr-qc↗

String reveals secrets of universe

Stringy cosmology displays features that are different from standard cosmology. One may be surprised in that in this scenario there is no phase transition between the radiation dominated phase and matter dominated phase and the universe is cyclic similar to brane cyclic cosmology.

physics.gen-ph↗

Hydrodynamics and global embeddings of Taub-NUT spacetime

On Taub-NUT spacetime, we investigate hydrodynamic properties of perfect fluid spiraling inward toward the spacetime along a conical surface. On the equatorial plane of the Taub-NUT spacetime, we derive radial equations of motion with effective potentials and the Euler equation for steady state axisymmetric fluid. Higher dimensional global embeddings are constructed inside and outside the event horizons of the Taub-NUT spacetime. We also study the effective potentials of particles on the Taub-NUT spacetime in terms of gravitational magnetic monopole strength of the source, total energy and angular momentum per unit rest mass of the particle.

gr-qc↗

BRST invariance and de Rham-type cohomology of 't Hooft-Polyakov monopole

We exploit the 't Hooft-Polyakov monopole to define closed algebra of the quantum field operators and the BRST charge $Q_{BRST}$. In the first-class configuration of the Dirac quantization, by including the $Q_{BRST}$-exact gauge fixing term and the Faddeev-Popov ghost term, we find the BRST invariant Hamiltonian to investigate the de Rham-type cohomology group structure for the monopole system. The Bogomol'nyi bound is also discussed in terms of the first-class topological charge defined on the extended internal 2-sphere.

hep-th↗

Singularities in geodesic surface congruence

In the stringy cosmology, we investigate singularities in geodesic surface congruences for the time-like and null strings to yield the Raychaudhuri type equations possessing correction terms associated with the novel features owing to the strings. Assuming the stringy strong energy condition, we have a Hawking-Penrose type inequality equation. If the initial expansion is negative so that the congruence is converging, we show that the expansion must pass through the singularity within a proper time. We observe that the stringy strong energy conditions of both the time-like and null string congruences produce the same inequality equation.

gr-qc↗

Sum rules for baryon decuplet magnetic moments

In chiral models with SU(3) group structure, baryon decuplet and octet magnetic moments are evaluated by constructing their sum rules to yield theoretical predictions. In these sum rules we exploit six experimentally known baryon magnetic moments. Sum rules for flavor components and strange form factors of the octet and decuplet magnetic moments and decuplet-to-octet transition magnetic moments are also investigated.

hep-ph↗

Morse theory in path space

We consider the path space of a curved manifold on which a point particle is introduced in a conservative physical system with constant total energy to formulate its action functional and geodesic equation together with breaks on the path. The second variation of the action functional is exploited to yield the geodesic deviation equation and to discuss the Jacobi fields on the curved manifold. We investigate the topology of the path space using the action functional on it and its physical meaning by defining the gradient of the action functional, the space of bounded flow energy solutions and the moduli space associated with the critical points of the action functional. We also consider the particle motion on the $n$-sphere $S^{n}$ in the conservative physical system to discuss explicitly the moduli space of the path space and the corresponding homology groups.

math-ph↗