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Yong-Shi Wu

Publications and source records attributed to Yong-Shi Wu.

At least 91 records · Page 5Linked to original sources
arXiv1998

Noncommutative Gauge Theories in Matrix Theory

We present a general framework for Matrix theory compactified on a quotient space R^n/G, with G a discrete group of Euclidean motions in R^n. The general solution to the quotient conditions gives a gauge theory on a noncommutative space. We characterize the resulting noncommutative gauge theory in terms of the twisted group algebra of G associated with a projective regular representation. Also we show how to extend our treatments to incorporate orientifolds.

hep-th↗
arXiv1998

Resonant Above-Threshold Ionization Peaks at Quantized Intensities

We suggest that electron-laser interactions can give rise to resonance phenomena as the intensity varies. A new QED perturbation theory is developed, in which the coupling between an electron and the second quantized laser mode is treated nonperturbatively. We predict, for example, the above-threshold ionization rate shows peaks at intensities with integer ponderomotive parameter. Such quantum resonance effects may be exploited to calibrate laser intensities in appropriate range.

physics.atom-ph↗
arXiv1998

Towards a Noncommutative Geometric Approach to Matrix Compactification

In this paper we study generic M(atrix) theory compactifications that are specified by a set of quotient conditions. A procedure is proposed, which both associates an algebra to each compactification and leads deductively to general solutions for the matrix variables. The notion of noncommutative geometry on the dual space is central to this construction. As examples we apply this procedure to various orbifolds and orientifolds, including ALE spaces and quotients of tori. While the old solutions are derived in a uniform way, new solutions are obtained in several cases. Our study also leads to a new formulation of gauge theory on quantum spaces.

hep-th↗
arXiv1997

Brane Creation in M(atrix) Theory

We discuss, in the context of M(atrix) theory, the creation of a membrane suspendend between two longitudinal five-branes when they cross each other. It is shown that the membrane creation is closely related to the degrees of freedom in the off-diagonal blocks which are related via dualities to the chiral fermionic zero mode on a 0-8 string. In the dual system of a D0-brane and a D8-brane in type \IIA theory the half-integral charges associated with the ``half''-strings are found to be connected to the well-known fermion-number fractionalization in the presence of a fermionic zero mode. At sufficiently short distances, the effective potential between the two five-branes is dominated by the zero mode contribution to the vacuum energy.

hep-th↗
arXiv1997

P-P' Strings in M(atrix) Theory

We study the off-diagonal blocks in the M(atrix) model that are supposed to correspond to open strings stretched between a Dp-brane and a Dp'-brane. It is shown that the spectrum, including the quantum numbers, of the zero modes in the off-diagonal blocks can be determined from the index theorem and unbroken supersymmetry, and indeed reproduces string theory predictions for p-p' strings. Previously the matrix description of a longitudinal fivebrane needed to introduce extra degrees of freedom corresponding to 0-4 strings by hand. We show that they are naturally associated with the off-diagonal zero modes, and the supersymmetry transformation laws and low energy effective action postulated for them are now derivable from the M(atrix) theory.

hep-th↗
arXiv1997

IIB/M Duality and Longitudinal Membranes in M(atrix) Theory

In this paper we study duality properties of the M(atrix) theory compactified on a circle. We establish the equivalence of this theory to the strong coupling limit of type IIB string theory compactified on a circle. In the M(atrix) theory context, our major evidence for this duality consists of identifying the BPS states of IIB strings in the spectrum and finding the remnant symmetry of SL(2,Z) and the associated tau moduli. By this IIB/M duality, a number of insights are gained into the physics of longitudinal membranes in the infinite momentum frame. We also point out an accidental affine Lie symmetry in the theory.

hep-th↗
arXiv1996

Noncommutative Geometry and D-Branes

We apply noncommutative geometry to a system of N parallel D-branes, which is interpreted as a quantum space. The Dirac operator defining the quantum differential calculus is identified to be the supercharge for strings connecting D-branes. As a result of the calculus, Connes' Yang-Mills action functional on the quantum space reproduces the dimensionally reduced U(N) super Yang-Mills action as the low energy effective action for D-brane dynamics. Several features that may look ad hoc in a noncommutative geometric construction are shown to have very natural physical or geometric origin in the D-brane picture in superstring theory.

hep-th↗
arXiv1996

Mutual Exclusion Statistics Between Quasiparticles in the Fractional Quantum Hall Effect

In this paper we propose a new assignment for mutual exclusion statistics between quasielectrons and quasiholes in the fractional quantum Hall effect. In addition to providing numerical evidence for this assignment, we show that the physical origin of this mutual statistics is a novel hard-core constraint due to correlation between the distinguishable vortex-like quasiparticles.

cond-mat↗
arXiv1996

Mean-Field and Perturbation Theory of Vortex-like Composite Fermions

We develop a field theory for a partially filled Landau level based on composite fermions with a finite vortex core, whose mean-field states are exactly those described by well-tested trial wave functions. Despite non-orthogonality of free composite-fermion states and non-Hermiticity of the mean-field Hamiltonian, a consistent perturbation theory is formulated and the mean-field Fermi sea at half filling is shown to be stable. While the low-energy and long-distance physics is the same as in the Chern-Simons fermion theory, new physics is expected to show up for larger wave vectors.

cond-mat↗
arXiv1995

Mutual Exclusion Statistics in the Exactly Solvable Model of the Mott Metal-Insulator Transition

We study statistical characterization of the many-body states in the exactly solvable model with internal degree of freedom in more than one dimension. The model exhibits the Mott metal-insulator transition. It is shown that the ground state is described by that of a generalized ideal gas of particles (called exclusons) which have mutual exclusion statistics between different species. In addition to giving a perspective view of spin-charge separation, the model constitutes an explicit example of mutual exclusion statistics in more than two dimensions.

cond-mat↗
arXiv1995

Hidden Massive Spectators in the Effective Field Theory for Integral Quantum Hall Transitions

Integral quantum Hall plateau transitions in a planar lattice system due to gap collapse can be described by an effective field theory with Dirac fermions. We discuss how to reproduce the correct integral values for the Hall conductance, $σ_{xy}$, before and after the plateau transition, which are dictated by the microscopic topological invariant. In addition to the massless Dirac fermions that appear at gap closing, the matching condition of $σ_{xy}$ requires the introduction of massive Dirac fermions, as "spectators", in the effective field theory. For non-interacting electrons on the lattice, we give a general prescription to determine these massive "spectators", based on microscopic information on the vortices in the magnetic Brillouin zone which are closely related to edge states. Our description is demonstrated in a model with both nearest-neighbor and next-nearest-neighbor hoppings.

cond-mat↗
arXiv1995

Bosonization of One-Dimensional Exclusons and Characterization of Luttinger Liquids

We achieve a bosonization of one-dimensional ideal gas of exclusion statistics $λ$ at low temperatures, resulting in a new variant of $c=1$ conformal field theory with compactified radius $R=\sqrt{1/λ}$. These ideal excluson gases exactly reproduce the low-$T$ critical properties of Luttinger liquids, so they can be used to characterize the fixed points of the latter. Generalized ideal gases with mutual statistics and non-ideal gases with Luttinger-type interactions have also similar behavior, controlled by an effective statistics varying in a fixed-point line.

cond-mat↗
arXiv1994

Explicit Solutions of the Bethe Ansatz Equations for Bloch Electrons in a Magnetic Field

For Bloch electrons in a magnetic field, explicit solutions are obtained at the center of the spectrum for the Bethe ansatz equations recently proposed by Wiegmann and Zabrodin. When the magnetic flux per plaquette is $1/Q$ where $Q$ is an odd integer, distribution of the roots is uniform on the unit circle in the complex plane. For the semi-classical limit, $ Q\rightarrow\infty$, the wavefunction obeys the power low and is given by $|ψ(x)|^2=(2/ \sin πx)$ which is critical and unnormalizable. For the golden mean flux, the distribution of roots has the exact self-similarity and the distribution function is nowhere differentiable. The corresponding wavefunction also shows a clear self-similar structure.

cond-mat↗
arXiv1994

Algebraic and geometric aspects of generalized quantum dynamics

\noindent We briefly discuss some algebraic and geometric aspects of the generalized Poisson bracket and non--commutative phase space for generalized quantum dynamics, which are analogous to properties of the classical Poisson bracket and ordinary symplectic structure.

hep-th↗
arXiv1994

A Note on Statistical Interactions and the Thermodynamic Bethe Ansatz

We show that the thermodynamic Bethe ansatz equations for one-dimensional integrable many-body systems can be reinterpreted in such a way that they only code the statistical interactions, in the sense of Haldane, between particles of identical or different momenta. Thus, the thermodynamic properties of these systems can be characterized by the generalized ideal gases recently proposed by one of us. For example, the Yang-Yang $δ$-function gas is a gas with specific statistical interactions between particles of different momenta, while the Calogero-Sutherland system provides a model for an ideal gas of particles with a fractional statistics.

cond-mat↗
arXiv1993

Chiral Operator Product Algebra and Edge Excitations of a Fractional Quantum Hall Droplet

In this paper we study the spectrum of low-energy edge excitations of a fractional quantum Hall (FQH) droplet. We show how to generate, by conformal field theory (CFT) techniques, the many-electron wave functions for the edge states. And we propose to classify the spectrum of the edge states by the same chiral operator product algebra (OPA) that appears in the CFT description of the ground state in the bulk. This bulk-edge correspondence is suggested particularly for FQH systems that support quasiparticle obeying non-abelian braid statistics, including the $ν=5/2$ Haldane-Rezayi state. Numerical diagonalization to count the low-lying edge states has been done for several non-abelian FQH systems, showing good agreement in all cases with the chiral OPA predictions. The specific heat of the edge excitations in those non-abelian states is also calculated.

cond-mat↗