arXiv subjects
Publications and source records attributed to Won Tae Kim.
We study Bell's inequality in relation to the Einstein-Podolsky-Rosen paradox in the relativistic regime. For this purpose, a relativistically invariant observable is used in the calculation of the Bell's inequality, which results in the maximally violated Bell's inequality in any reference frames.
We study the low-energy dynamics of an acoustic black hole near the sonic horizon. For the experimental test of black hole evaporation in the laboratory, the decay rate (greybody factor) of the acoustic black hole (sonic hole) can be calculated by the usual low-energy perturbation method. As a consequence, we obtain the decay rate of the sonic horizon from the absorption and the reflection coefficients. Moreover, we show that the thermal emission from the sonic horizon is only proportional to a control parameter which describes the velocity of the fluid.
We are presenting a quantum traversable wormhole in an exactly soluble two-dimensional model. This is different from previous works since the exotic negative energy that supports the wormhole is generated from the quantization of classical energy-momentum tensors. This explicit illustration shows the quantum-mechanical energy can be used as a candidate for the exotic source. As for the traversability, after a particle travels through the wormhole, the static initial wormhole geometry gets a back reaction which spoils the wormhole structure. However, it may still maintain the initial structure along with the appropriate boundary condition.
We show that the RST model describing the exactly soluble black hole model can have a dynamical wormhole solution along with an appropriate boundary condition. The necessary exotic matter which is usually negative energy density is remarkably produced by the quantization of the infalling matter fields. Then the asymptotic geometry in the past is two-dimensional anti-de Sitter(AdS$_2$), which implies the exotic matter is negative. As time goes on, the wormhole eventually evolves into the black hole and its Hawking radiation appears. The throat of the static RST wormhole is lower-bounded but in the presence of infalling matter it collapses to a black hole.
We consider D-particles coupled to the CGHS dilaton gravity and obtain the exact wormhole geometry and trajectories of D-particles by introducing the exotic matter. The initial static wormhole background is not stable after infalling D-particles due to the classical backreaction of the geometry so that the additional exotic matter source should be introduced for the stability. Then, the traversable wormhole geometry naturally appears and the D-particles can travel through it safely. Finally, we discuss the dynamical evolution of the wormhole throat and the massless limit of D-particles.
We present an exactly soluble charged wormhole model in two dimensions by adding infalling chiral fermions on the static wormhole. The infalling energy due to the infalling charged matter requires the classical back reaction of the geometry, which is solved by taking into account of the nontrivial nonchiral exotic energy. Finally, we obtain the exact expression for the size of the throat depending on the total amount of the infalling net energy and discuss the interesting transition from the AdS spacetime to the wormhole geometry.
We study traversable Lorentzian wormholes in the three-dimensional low energy string theory by adding some matter source involving a dilaton field. It will be shown that there are two-different types of wormhole solutions such as BTZ and black string wormholes depending on the dilaton backgrounds, respectively. We finally obtain the desirable solutions which confine exotic matter near the throat of wormhole by adjusting NS charge.
We obtain minimal (2+1) and (2+2) dimensional global flat embeddings of uncharged and charged dilatonic black holes in (1+1) dimensions, respectively. Moreover, we obtain the Hawking temperatures and the black hole ones of these dilatonic black holes. However, even though the minimal flat embedding structures are mathematically meaningful, through this minimal embeddings the proper entropies are shown to be unattainable, contrast to the cases of other black holes in (2+1) or much higher dimensions.
We study the duality of quasilocal energy and charges with non-orthogonal boundaries in the (2+1)-dimensional low-energy string theory. Quasilocal quantities shown in the previous work and some new variables arisen from considering the non-orthogonal boundaries as well are presented, and the boost relations between those quantities are discussed. Moreover, we show that the dual properties of quasilocal variables such as quasilocal energy density, momentum densities, surface stress densities, dilaton pressure densities, and Neuve-Schwarz(NS) charge density, are still valid in the moving observer's frame.
In the asymptotically flat two-dimensional dilaton gravity, we present an N-body particle action which has a dilaton coupled mass term for the exact solubility. This gives nonperturbative exact solutions for the N-body self-gravitating system, so the infalling particles form a black hole and their trajectories are exactly described. In our two-dimensional case, the critical mass for the formation of black holes does not exist, so even a single particle forms a black hole, which means that we can treat many black holes. The infalling particles give additional time-like singularities in addition to the space-like black hole singularity. However, the latter singularities can be properly cloaked by the future horizons within some conditions.
We minimized the interface diffuseness in the phase-field models by introducing the parabolic double-well potential and localizing the solute redistribution (or latent heat release) into a narrow region within the phase-field interface. In spite of the parabolic potential with cusps, highly localized solute redistribution and discontinuous diffusivity function adopted in this model, it works remarkably well in numerical computations. The computations on dendritic solidification of an one-sided system yield quantitatively the same results with the anti-trapping model [A. Karma, Phys. Rev. Lett. 87, 115701 (2001)], indicating the anomalous interfacial effects can be effectively suppressed. This approach can be easily extended to the multi-components or multi-phases system.
We study thermodynamic evaporation of Schwarzschild-de Sitter black holes in terms of a low energy perturbation theory. A small black hole which is far from the cosmological horizon and observers at the spacelike hypersurface where black hole attraction and expansion of cosmological horizon balance exactly are considered. In the low energy perturbation, scalar field equations are solved in both regions of the hypersurface and scattering amplitudes are derived. And then the desired thermal temperatures from the two horizons are obtained as a ``minimal'' value of the statistical thermal temperature, and the fine-tuning between amplitudes gives a relation of the two temperatures.
The nonholonomic constrained system with second-class constraints is investigated using the Hamilton-Jacobi (HJ) quantization scheme to yield the complete equations of motion of the system. Although the integrability conditions in the HJ scheme are equivalent to the involutive relations for the first-class constrained system in the improved Dirac quantization method (DQM), one should elaborate the HJ scheme by using the improved DQM in order to obtain the first-class Hamiltonian and the corresponding effective Lagrangian having the BRST invariant nonholonomic constrained system.
We study quasinormal modes of massless scalar and fermion fields in the near extremal Reissner-Nordstr{ö}m black hole, and relate them to Choptuik scaling form following a recently proposed analytic approach. For both massless cases, quasinormal modes are shown to be proportional to the black hole horizon and the Hawking temperature, and the critical exponents are the same, although for the fermionic case there are two possible discrete quasinormal modes. In addition, the critical exponent of the massive boson is also equivalent to that of the massless case. Finally, we discuss quasinormal modes and critical exponents in the other models, and obtain some different critical exponents between massless boson and massive one.
We calculate the entropy of the brane-world black hole in the Randall-Sundrum(RS) model by using the brick-wall method. The modes along the extra dimension are semi-classically quantized on the extra dimension. The number of modes in the extra dimension is given as a simple form with the help of the RS mass relation, and then the entropy for the scalar modes in the five-dimensional spacetime is described by the two-dimensional area of the black brane world.
We obtain (3+1) and (3+2) dimensional global flat embeddings of (2+1) uncharged and charged black strings, respectively. In particular, the charged black string, which is the dual solution of the Banados-Teitelboim-Zanelli black holes, is shown to be embedded in the same global embedding Minkowski space structure as that of the (2+1) charged de Sitter black hole solution.
We study brane-world black holes from Randall-Sundrum(RS) models in ($D+1$)-dimensional anti-de Sitter spacetimes. The solutions are directly obtained by using a slightly modified RS metric ansatz in $D+1$ dimensions. The metric of the brane world can be described by the Schwarzschild solution promoted to the black cigar solution in $D+1$ dimensions, which is compatible with the recently suggested black cigar solution for D=4. Furthermore, we show that the Ricci flat condition for the brane can be easily derived from the effective gravity defined on the brane by using the RS dimensional reduction. Especially, it is shown that in two dimensions the effective gravity on the brane is described by the Polyakov action.
In the framework of Dirac quantization with second class constraints, a free particle moving on the surface of a $(d-1)-$dimensional sphere has an ambiguity in the energy spectrum due to the arbitrary shift of canonical momenta. We explicitly show that this spectrum obtained by the Dirac method can be consistent with the result of the Batalin-Fradkin-Tyutin formalism, which is an improved Dirac method, at the level of the first-class constraint by fixing the ambiguity, and discuss its physical consequences.