125269418
Tachyon condensation, boundary state and string field theory
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.
123683308
STRING THEORY AND DUALITIES IN THE QUANTUM DISSIPATIVE HOFSTADTER SYSTEM
We study the dualities of the quantum dissipative Hofstadter system which describes particles moving in two dimensions, subject to a uniform magnetic field, a periodic potential and a dissipative force. Using the string theory formulation, we show that the system has two kinds of dualities. The duality, previously known as the exact duality in the literature is shown to correspond to a subgroup of the T-dual symmetry group unbroken by the periodic boundary potential in string theory. The other duality is a particle–kink duality in the noncommutative open string theory which is a generalized Schmid duality in the presence of the uniform magnetic field. The kinks of the dissipative Hofstadter model are found to be noncommutative objects. The particle–kink duality, which is called previously the approximate duality, is shown to be also exact. In contrast to the previous derivation, which is based on the Coulomb gas expansion of the partition function and asserts that the duality holds only approximately in t...
119336241
The Chern-Simons coefficient in the Higgs phase
Abstract We study one-loop corrections to the Chern-Simons coefficient ϰ in abelian self-dual Chern-Simons Higgs systems and their N =2 and N =3 supersymmetric generalizations in both symmetric and asymmetric phases. One-loop corrections to the Chern-Simons coefficient of these systems turn out to be integer multiples of 1 4 π in both phases. Especially in the maximally supersymmetric N =3 case, the correction in the symmetric phase vanishes and that in the asymmetric phase is ϰ /(2 π | ϰ |). Our results suggest that nonabelian self-dual system might enjoy similar features. We also discuss various issues arising from our results.
119489587
Fermion representation of the rolling tachyon boundary conformal field theory
A free fermion representation of the rolling tachyon boundary conformal field theory is constructed. The representation is used to obtain an explicit, compact, exact expression for the boundary state. We use the boundary state to compute the disc and cylinder amplitudes for the half-S-brane.
37673623
Apparatus-dependent contributions to g-2?
The University of Washington g-2 experiments have progressed to the marvelous precision of 10/sup 12/ in their measurement of the magnetic moment of the electron. A further improvement of a factor of 10 should occur in the near future. Concomitant with this accuracy is the necessity of understanding small corrections. These experiments employ a Penning trap whose electrodes behave as conducting walls for a microwave cavity. We investigate the effect of this cavity on the spin and cyclotron frequencies. Previous work, employing calculations that are not gauge invariant, implies that the present level of accuracy cannot be exceeded because of cavity effects on the spin precession frequency. In contrast to this erroneous work, we find no significant correction to the spin precession frequency, but we do find that the correction to the cyclotron frequency will be important when the experiments improve by another order of magnitude. 9 references.
117208394
Scalar Nonluminous Matter in Galaxies
As a candidate for dark matter in galaxies, we study an SU(3) triplet of complex scalar fields which are nonminimally coupled to gravity. In the spherically symmetric static space–time where the flat rotational velocity curves of stars in galaxies can be explained, we find simple solutions of scalar fields with SU(3) global symmetry broken to U(1) × U(1), in an exponential scalar potential, which will be useful in a quintessence model of the late-time acceleration of the universe.
500527
Renormalons beyond one loop
Higher order renormalons beyond the chain of one-loop bubbles are discussed. A perturbation method for the infrared renormalon residue is found. The large order behavior of the current-current correlation function due to the first infrared renormalon is determined in both QED and QCD to the first three orders. {copyright} {ital 1997} {ital The American Physical Society}
121048591
Some power-law cosmological solutions derived from the 5D Brans-Dicke vacuum theory
We solve vacuum field equations in five-dimensional Brans–Dicke gravity to find power-law growth for the cosmological scale factor, with the range of its parameter values extended by the Brans–Dicke field. We discuss its implications for the onset of late-time cosmic acceleration.
118566101
Higher dimensional cosmological model with a phantom field
We consider a higher dimensional gravity theory with a negative kinetic energy scalar field and a cosmological constant. We find that the theory admits an exact cosmological solution for the scale factor of our universe. It has the feature that the universe undergoes a continuous transition from deceleration to acceleration at some finite time. This transition time can be interpreted as that of recent acceleration of our universe.
118864807
Particle with non-Abelian charge: classical and quantum
We study the action for a non-Abelian charged particle in a non-Abelian background field in the worldline formalism, described by real bosonic variables, leading to the well known equations given by Wong. The isospin parts in the action can be viewed as the Lagrange multiplier term corresponding to a non-holonomic constraint restricting the isospins to be parallel transported. The path integration is performed over the isospin variables and as a result, the worldlines turn out to be constrained by the classical solutions for the isospins. We derive a wave equation from the path integral, constructed as the constrained Hamiltonian operator acting on the wave function. The operator ordering corresponding to the quantum Hamiltonian is found and verified by the inverse Weyl transformation.