Sung Ku Kim

Bounds on the Soft Pomeron Intercept

The Donnachie-Landshoff fit of total cross sections has now become a standard reference for models of total, elastic and diffractive cross-sections. Adopting their philosophy that simple-pole exchanges should account for all data to present energies, we assess the uncertainties on their fits, and show that the pomeron intercept which controls total cross sections and the real part of the elastic amplitude, can lie anywhere between 1.07 and 1.1, with a preferred value 1.094. supported in part by the USDOE contract DE-FG02-91ER 40688-Task A. supported in part by the Korea Science and Engineering Foundation through the Center for Theoretical Physics, Seoul National University, and by the Ministry of Education through contract BSRI-95-2427.Abstract The Donnachie-Landshoff fit of total cross sections has now become a standard reference for models of total, elastic and diffractive cross-sections. Adopting their philosophy that simple-pole exchanges should account for all data to present energies, we assess the uncertainties on their fits. Our best estimate for the pomeron intercept is 1.096−0.009+0.012, but several models have a good χ2 for intercepts in the range [1.07,1.11].

Noncommutative Chern-Simons solitons

The Chern-Simons theories on a noncommutative plane, which is shown to be describing the quantum Hall liquid, is considered. We introduce matter fields fundamentally coupled to the noncommutative Chern-Simons field. Exploiting BPS equations for the nonrelativistic Chern-Simons theory, we find the exact solutions of multi vortices that are closely packed and exponentially localized. We determine the position, the size and the angular momentum explicitly. We then construct the solutions of two spatially separated vortices and determine the moduli dependence of the size and the angular momentum. We also consider the relativistic Chern-Simons theory and find nontopological solutions whose properties are similar to the nonrelativistic counterpart. However, unlike the nonrelativistic case, there are two branches of solutions for a given magnetic field and they cease to exist below certain noncommutativity scale.

Renormalized thermodynamic entropy of black holes in higher dimensions

We study the ultraviolet divergent structures of the matter (scalar) field in a higher D-dimensional Reissner-Nordstr{umlt o}m black hole and compute the matter field contribution to the Bekenstein-Hawking entropy by using the Pauli-Villars regularization method. We find that the matter field contribution to the black hole entropy does not, in general, yield the correct renormalization of the gravitational coupling constants. In particular, we show that the matter field contribution in odd dimensions does not give the term proportional to the area of the black hole event horizon. {copyright} {ital 1997} {ital The American Physical Society}

Exact wave functions in a noncommutative field theory

We consider the nonrelativistic field theory with a quartic interaction on a noncommutative plane and compute the 2-->2 scattering amplitude within perturbative analysis to all orders. We regain the results of the perturbative analysis by finding the scattering and the bound state wave functions of the two particle Schrodinger equation. These wave functions unusually have two center positions in the relative coordinates, whose separation is transverse to the total momentum and scales linearly with its magnitude, exhibiting the stringy nature of the noncommutative field theory.

Remarks on Renormalization of Black Hole Entropy

We elaborate the renormalization process of entropy of a nonextremal and an extremal Reissner–Nordstrom black hole by using the Pauli–Villars regularization method, in which the regulator fields obey either the Bose–Einstein or Fermi–Dirac distribution depending on their spin-statistics. The black hole entropy involves only two renormalization constants. We also discuss the entropy and temperature of the extremal black hole.

Statistical interactions between Chern-Simons vortices

Abstract Considering slow motion of the self-dual Chern-Simons vortices, we have derived an effective lagrangian from the underlying field theory. Our lagrangian contains a statistical interaction term with the value of the statistical factor in agreement with the generalized spin-statistics relation.

Quantum inflaton dynamics

We show that the quantum dynamics of a real scalar field for a large class of potentials in the symmetric Gaussian state, where the nonperturbative quantum contributions are taken into account, can be described equivalently by a two-dimensional nonlinear dynamical system with a definite angular momentum (U(1) charge of a complex theory). It is found that the Gaussian state with a nearly minimal uncertainty and a large quantum fluctuation, as an initial condition, naturally explains the most of the essential features of the early stage of the inflationary Universe.

Noncommutative fermionic field theories with smooth commutative limit

We consider two model field theories on a noncommutative plane that have smooth commutative limits. One is the single-component fermion theory with quartic interaction that vanishes identically in the commutative limit. The other is a scalar-fermion theory, which extends the scalar field theory with quartic interaction by adding a fermion. We compute the bound state energies and the two particle scattering amplitudes exactly.

(1+1)-dimensional gravity through a dimensional reduction

Abstract The GL(2, R ) gauge theory of (1+1)-dimensional gravity, which contains the Jackiw-Teitelboim model and the dilaton gravity model as special cases, is derived as a dimensional reduction of a (2+1)-dimensional Chern-Simons gravity based on the gauge group SO(3, 1)⊗GL(1, R ).

Quantum creation of a black hole by tunneling in scalar field collapse

The continuously self-similar solution of the spherically symmetric gravitational collapse of a scalar field is studied to investigate quantum-mechanical black-hole formation by tunneling in the subcritical case, where, classically, the collapse does not produce a black hole.