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Dongsu Bak

Publications and source records attributed to Dongsu Bak.

116 records · Page 7Linked to original sources
arXiv1997

Boundary degrees of freedom in fractional quantum Hall effect: Excitations on common boundary of two samples

Using the Carlip's method we have derived the boundary action for the fermion Chern-Simons theory of quantum Hall effects on a planar region with a boundary. We have computed both the bulk and edge responses of currents to the external electric field. From this we obtain the well-known anomaly relation and the boundary Hall current without introducing any ad hoc assumptions such as the chirality condition. In addition, the edge current on the common boundary of two samples is found to be proportional to the difference between Chern-Simons coupling strengths.

cond-mat↗
arXiv1997

Moduli Space Dynamics of a First-Order Vortex System

The moduli space dynamics of vortices in the Jackiw-Pi model where a non-relativistic Schrodinger field couples minimally to Chern-Simons gauge field, is considered. It is shown that the difficulties in direct application of Manton's method to obtain a moduli-space metric in the first order system can be circumvented by turning the Lagrangian into a second order system. We obtain exact metrics for some simple cases and describe how the vortices respond to an external U(1) field. We then construct an effective Lagrangian describing dynamics of the vortices. In addition, we clarify strong-weak coupling duality between fundamental particles and vortices.

hep-th↗
arXiv1997

Radiation Damping of a BPS Monopole; an Implication to S-duality

The radiation reaction of a BPS monopole in the presence of incident electromagnetic waves as well as massless Higgs waves is analyzed classically. The reactive forces are compared to those of $W$ boson that is interpreted as a dual partner of the BPS monopole. It is shown that the damping of acceleration is dual to each other, while in the case of finite size effects the duality is broken explicitly. Their implications on the duality are discussed.

hep-th↗
arXiv1995

String-Inspired Gravity with Interacting Point Particles

We reformulate two dimensional string-inspired gravity with point particles as a gauge theory of the extended Poincaré group. A non-minimal gauge coupling is necessary for the equivalence of the two descriptions. The classical one-particle problem is analyzed completely. In addition, we obtain the many-particle effective action after eliminating the gravity degrees of freedom. We investigate properties of this effective action, and show how to recover the geometrical description. Quantization of the gauge-theoretic model is carried out and the explicit one-particle solution is found. However, we show that the formulation leads to a quantum mechanical inconsistency in the two-particle case. Possible cures are discussed.

hep-th↗
arXiv1994

Perturbative Analysis of Nonabelian Aharonov-Bohm Scattering

We perform a perturbative analysis of the nonabelian Aharonov-Bohm problem to one loop in a field theoretic framework, and show the necessity of contact interactions for renormalizability of perturbation theory. Moreover at critical values of the contact interaction strength the theory is finite and preserves classical conformal invariance.

hep-th↗
arXiv1994

Non-Abelian Chern-Simons Particles and their Quantization

A many--body Schrödinger equation for non--Abelian Chern--Simons particles is obtained from both point--particle and field--theoretic pictures. We present a particle Lagrangian and a field theoretic Lagrange density, and discuss their properties. Both are quantized by the symplectic method of Hamiltonian reduction. An $N$--body Schrödinger equation for the particles is obtained from both starting points. It is shown that the resulting interaction between particles can be replaced by non--trivial boundary conditions. Also, the equation is compared with the one given in the literature.

hep-th↗
arXiv1993

Energy-Momentum Conservation in General Relativity

We discuss general properties of the conservation law associated with a local symmetry. Using Noether's theorem and a generalized Belinfante symmetrization procedure in 3+1 dimensions, a symmetric energy-momentum (pseudo) tensor for the gravitational Einstein-Hilbert action is derived and discussed in detail. In 2+1 dimensions, expressions are obtained for energy and angular momentum arising in the $ISO(2,1)$ gauge theoretical formulation of Einstein gravity. In addition, an expression for energy in a gauge theoretical formulation of the string-inspired 1+1 dimensional gravity is derived and compared with the ADM definition of energy.

hep-th↗