119024822
Boundary State for Dissipative Quantum Mechanics and Thirring Model
The dissipative quantum system is studied using the Thirring model with a boundary mass. At the critical point where the Thirring coupling vanishes, the theory reduces to a free fermion theory with a boundary mass. We construct boundary states for the dissipative quantum systems in one dimension, which describes the system off the critical points as well as at the critical points.
118937531
Discrete light cone quantization of anti-de Sitter black hole and black string
56316687
Quantum Brownian Motion on a Triangular Lattice and Fermi-Bose Equivalence: An Application of Boundary State Formulation
We discuss the Bose-Fermi equivalence in the quantum Brownian motion (QBM) on a triangular lattice, mapping the action for the QBM into a string theory action with a periodic boundary tachyon potential. We construct new Klein factors which are more appropriate than the conventional ones to deal with the quantum field theories defined on a two dimensioanl space-time with boundaries. Using the Fermi-Bose equivalence with the new Klein factors, we show that the model for the quantum Bownian motion on a triangular lattice is equivalent to the Thirring model with boundary terms, which are quadratic in fermion field operators, in the off-critical regions and to a SU(3) × SU(3) free fermion theory with quadratic boundary terms at the critical point.
119401888
Tachyon condensation, boundary state, and noncommutative solitons
We discuss tachyon condensation in a single unstable D-brane in the framework of the boundary state formulation. The boundary state in the background of tachyon condensation and the Neveu-Schwarz B-field is explicitly constructed. We show in both commutative theory and noncommutative theory that the unstable D-branes behave like an extended object and eventually reduce to lower dimensional D-branes as the system approaches the infrared fixed point. We clarify the relationship between the commutative field theoretical description of tachyon condensation and the noncommutative one.
117114158
Relativistic Anyon and (2+1) Dimensional Gravity
18394193
Topological Ward identity and anti-de Sitter space / CFT correspondence
Abstract The dual relationship between the supergravity in the anti-de Sitter (AdS) space and the superconformal field theory is discussed in the simplest form. We show that a topological Ward identity holds in the three dimensional Chern–Simons gravity. In this simple case the proposed dual relationship can be understood as the topological Ward identity. Extensions to the supersymmetric theories and higher dimensional ones are also briefly discussed.
18838676
de Sitter nonlinear sigma model and accelerating universe
We consider a cosmology with a noncompact nonlinear sigma model. The target space is of de Sitter type and four scalar fields are introduced. The potential is absent but cosmological constant term {lambda} is added. One of the scalar fields is time dependent and the remaining three fields have no time dependence but only spatial dependence. We show that a very simple ansatz for the scalar fields results in the accelerating universe with an exponential expansion at late times. It is pointed out that the presence of the energy density and pressure coming from the spatial variation of the three scalar fields plays an essential role in our analysis which includes {lambda}=0 as a special case and it discriminate from the standard {lambda}-dominated acceleration. We perform a stability analysis of the solutions and find that some solutions are classically stable and attractor. We also present a nonperturbative solution which asymptotically approaches an exponential acceleration and discuss possible cosmological implications in relation to dark energy. It turns out that the equation of state approaches asymptotically {omega}=-1 both from above and below, but the crossing does not occur. It predicts present value of {omega}{approx}-1{+-}0.07, which is within the region allowed by themore » observational data. This solution also exhibits a power law expansion at early times, and the energy density of the scalar fields mimics that of the stiff matter.« less
11094891
A complete solution of a constrained system: SUSY monopole quantum mechanics
We solve the quantum mechanical problem of a charged particle on S2 in the background of a magnetic monopole for both bosonic and supersymmetric particles by constructing Hilbert space and realizing the fundamental operators obeying complicated Dirac bracket relations in terms of differential operators. We find the complete energy eigenfunctions. Using the lowest energy eigenstates we count the number of degeneracies and examine the supersymmetry structure of the ground states in detail.
118456991
Mass dependence of the vacuum energy density in the massive Schwinger model
The vacuum energy density of the massive Schwinger model is shown to be not power expandable in the fermion mass.
18009336
Supersymmetric monopole quantum mechanics on a sphere
We study $N=2$ supersymmetric quantum mechanics of a charged particle on sphere in the background of Dirac magnetic monopole. We adopt $CP(1)$ model approach in which the monopole interaction is free of singularity. It turns out that this approach admits a compact $N=2$ superspace formulation. In order to exploit manifest U(1) covariance in the superspace formalism, we introduce a gauged chiral superfield which is annihilated by the gauge covariant superderivative instead of the usual superderivative. We carry out the Dirac quantization of the resulting system and compute the quantum mechanical spectrum. We obtain the condition for the spontaneous breaking of supersymmetry explicitly in terms of the monopole charge and a parameter which characterizes the operator ordering ambiguity. We find that the supersymmetry is spontaneously broken unless a certain combination of these quantities satisfies some quantization condition.
39461914
Heavy quark mass determination from the quarkonium ground state energy: a pole mass approach
The heavy quark pole mass in perturbation theory suffers from a renormalon caused, inherent uncertainty of O(?QCD). This fundamental difficulty of determining the pole mass to an accuracy better than the inherent uncertainty can be overcome by direct resummation of the first infrared renormalon. We show how a properly defined pole mass as well as the mass for the top and bottom quarks can be determined accurately from the O(m?s5) quarkonium ground state energy.