Light-Front Aspects of Chiral Symmetry

Spontaneous chiral symmetry breaking and axial anomaly are studied in the light-front formulation. The existence of multiple vacua and a Nambu-Goldstone boson, both related to dynamical fermion zero modes, are demonstrated within a simple sigma model with fermions. The Weyl gauge formulation and a consistent gauge invariant point-splitting regularization, which includes the light front time, are crucial for obtaining the anomaly in the massive Schwinger model and QED(3+1).Comment: 5 pages, Latex2e, uses elsart.cls, to apper in the proceedings of the X. International Light-Cone Meeting, Heidelberg, June 200

The Massive Schwinger Model in a Fast Moving Frame

We present a non-perturbative study of the massive Schwinger model. We use a Hamiltonian approach, based on a momentum lattice corresponding to a fast moving reference frame, and equal time quantization.Comment: contribution to Lattice'98 including: 2 style files (espcrc2.sty,psfig.sty) + text file (LaTeX) + 3 figures (ps) + complete paper(ps

Solution of the Thirring Model with Imaginary Mass and Massless Scattering

The Thirring model with imaginary mass (or the sine-Gordon model with imaginary coupling) is deeply related to all the flows between minimal conformal theories. We solve this model explicitely using the Bethe ansatz. We find that there are Left and Right moving massless excitations with non trivial LR scattering. We compute the S matrix and recover the result conjectured by Fendley et al.Comment: 14 pages, 2 figures, uses harvmac macros. Preprint USC-94-00

Reply to ``Comment on `Properties of the massive Thirring model from the XYZ spin chain' "

We elaborate in more details why lattice calculation in [Kolanovic et al, Phys. Rev. D 62, 025021 (2000)] was done correctly and argue that incresing the number of sites is not expected to change our conclusions on the mass spectrum.Comment: 2 pages, revtex 4, to be published in Phys. Rev.

Strong Coupling Limit of Bethe Ansatz Solutions in Massive Thirring Model

We study the strong coupling limit of the Bethe ansatz solutions in the massive Thirring model. We find analytical expressions for the energy eigenvalues for the vacuum state as well as n-particle n- hole states. This formula is compared with the numerical results and is found to achieve a very good agreement. Also, it is found that the 2-particle 2- hole and higher particle-hole states describe n- free bosons states in this limit. The behaviors of the strong coupling limit of the boson mass for various model calculations are examined. We discuss an ambiguity of the coupling constant normalization due to the current regularization.Comment: 15 pages, to appear in Ann. Phys. 281 (2000), Ma

A new interpretation of Bethe ansatz solutions for massive Thirring model

We reexamine Bethe ansatz solutions of the massive Thirring model. We solve equations of periodic boundary conditions numerically without referring to the density of states. It is found that there is only one bound state in the massive Thirring model. The bound state spectrum obtained here is consistent with Fujita-Ogura's solutions of the infinite momentum frame prescription. Further, it turns out that there exist no solutions for string-like configurations. Instead, we find boson boson scattering states in 2-particle 2-hole configurations where all the rapidity variables turn out to be real.Comment: 36 pages, Latex, no figure

Non-equivalence between Heisenberg XXZ spin chain and Thirring model

The Bethe ansatz equations for the spin 1/2 Heisenberg XXZ spin chain are numerically solved, and the energy eigenvalues are determined for the anti-ferromagnetic case. We examine the relation between the XXZ spin chain and the Thirring model, and show that the spectrum of the XXZ spin chain is different from that of the regularized Thirring model.Comment: 10 pages. 2figure

A local and integrable lattice regularization of the massive Thirring model

The light--cone lattice approach to the massive Thirring model is reformulated using a local and integrable lattice Hamiltonian written in terms of discrete fermi fields. Several subtle points concerning boundary conditions, normal--ordering, continuum limit, finite renormalizations and decoupling of fermion doublers are elucidated. The relations connecting the six--vertex anisotropy and the various coupling constants of the continuum are analyzed in detail.Comment: Latex, 24 pages, some corrected misprints and minor changes, 2 Postscript figures unchange