DMRG studies of critical SU(N) spin chains

The DMRG method is applied to integrable models of antiferromagnetic spin chains for fundamental and higher representations of SU(2), SU(3), and SU(4). From the low energy spectrum and the entanglement entropy, we compute the central charge and the primary field scaling dimensions. These parameters allow us to identify uniquely the Wess-Zumino-Witten models capturing the low energy sectors of the models we consider.Comment: 14 pages, 8 figures; final version, to appear in Ann. Phy

On the Construction of Trigonometric Solutions of the Yang-Baxter Equation

We describe the construction of trigonometric R-matrices corresponding to the (multiplicity-free) tensor product of any two irreducible representations of a quantum algebra U_q(\G). Our method is a generalization of the tensor product graph method to the case of two different representations. It yields the decomposition of the R-matrix into projection operators. Many new examples of trigonometric R-matrices (solutions to the spectral parameter dependent Yang-Baxter equation) are constructed using this approach.Comment: latex file, 29 pages, Universitaet Bielefeld and University of Queensland preprint, BI-TP-94/13, UQMATH-94-02 (minor correction: in eq. (4.63) the number 32 should be replaced by 36 and in eq. (4.64) -16 becomes -18 and -10 becomes -8.

Bethe Ansatz for 1D interacting anyons

This article gives a pedagogic derivation of the Bethe Ansatz solution for 1D interacting anyons. This includes a demonstration of the subtle role of the anyonic phases in the Bethe Ansatz arising from the anyonic commutation relations. The thermodynamic Bethe Ansatz equations defining the temperature dependent properties of the model are also derived, from which some groundstate properties are obtained.Comment: 22 pages, two references added, small improvements to tex

Excitation Spectrum of S=1S=1 Antiferromagnetic Chains

The dynamical structure factor $S(Q,\omega)$ of the $S=1$ antiferromagnetic Heisenberg chain with length 20 at zero temperature is calculated. The lowest energy states have the delta-function peak at the region $\pi\ge \vert Q\vert >0.3\pi$. At $\vert Q\vert<0.3\pi$ the lowest energy states are the lower-edge of the continuum of the scattering state, the strength of which decreases for large systems. This gives a reasonable explanation for the experimental fact that no clear peak is observed at the region $Q<0.3\pi$. This situation is more apparent for valence-bond solid state. On the contrary for $S=1/2$ antiferromagnetic Heisenberg chain the lowest energy states are always the edge of the continuum.Comment: 14pages, Revtex 3.0, No.279

The Radiative Corrections to the Mass of the Kink Using an Alternative Renormalization Program

In this paper we compute the radiative correction to the mass of the kink in $\phi^4$ theory in 1+1 dimensions, using an alternative renormalization program. In this newly proposed renormalization program the breaking of the translational invariance and the topological nature of the problem, due to the presence of the kink, is automatically taken into account. This will naturally lead to uniquely defined position dependent counterterms. We use the mode number cutoff in conjunction with the above program to compute the mass of the kink up to and including the next to the leading order quantum correction. We discuss the differences between the results of this procedure and the previously reported ones.Comment: 8 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:0806.036

Ground State and Excitations of Spin Chain with Orbital Degeneracy

The one dimensional Heisenberg model in the presence of orbital degeneracy is studied at the SU(4) symmetric viewpoint by means of Bethe ansatz. Following Sutherland's previous work on an equivalent model, we discuss the ground state and the low-lying excitations more extensively in connection to the spin systems with orbital degeneracy. We show explicitly that the ground state is a SU(4) singlet. We study the degeneracies of the elementary excitations and the spectra of the generalized magnons consisting of these excitations. We also discuss the complex 2-strings in the context of the Bethe ansatz solutions.Comment: Revtex, 9 pages, 3 figures; typos correcte

Odderon in baryon-baryon scattering from the AdS/CFT correspondence

Based on the AdS/CFT correspondence, we present a holographic description of various C-odd exchanges in high energy baryon-baryon and baryon-antibaryon scattering, and calculate their respective contributions to the difference in the total cross sections. We predict that, due to the warp factor of AdS_5, the total cross section in pp collisions is larger than in p\bar{p} collisions at asymptotically high energies.Comment: 23 pages, v2: minor changes, to be published in JHE

Electron and Photon Scattering on Three-Nucleon Bound States

A big spectrum of processes induced by real and virtual photons on the 3He and 3H nuclei is theoretically investigated through many examples based on nonrelativistic Faddeev calculations for bound and continuum states. The modern nucleon-nucleon potential AV18 together with the three-nucleon force UrbanaIX is used. The single nucleon current is augmented by explicit pi- and rho-like two-body currents which fulfill the current continuity equation together with the corresponding parts of the AV18 potential. We also employ the Siegert theorem, which induces many-body contributions to the current operator. The interplay of these different dynamical ingredients in the various electromagnetic processes is studied and the theory is compared to the experimental data. Overall we find fair to good agreement but also cases of strong disagreement between theory and experiment, which calls for improved dynamics. In several cases we refer the reader to the work of other groups and compare their results with ours. In addition we list a number of predictions for observables in different processes which would challenge this dynamical scenario even more stringently and systematically.Comment: 154 pages, 80 figures includes as ps files, 21 additional figures as jpeg file

Self-consistent Green's function method for nuclei and nuclear matter

Recent results obtained by applying the method of self-consistent Green's functions to nuclei and nuclear matter are reviewed. Particular attention is given to the description of experimental data obtained from the (e,e'p) and (e,e'2N) reactions that determine one and two-nucleon removal probabilities in nuclei since the corresponding amplitudes are directly related to the imaginary parts of the single-particle and two-particle propagators. For this reason and the fact that these amplitudes can now be calculated with the inclusion of all the relevant physical processes, it is useful to explore the efficacy of the method of self-consistent Green's functions in describing these experimental data. Results for both finite nuclei and nuclear matter are discussed with particular emphasis on clarifying the role of short-range correlations in determining various experimental quantities. The important role of long-range correlations in determining the structure of low-energy correlations is also documented. For a complete understanding of nuclear phenomena it is therefore essential to include both types of physical correlations. We demonstrate that recent experimental results for these reactions combined with the reported theoretical calculations yield a very clear understanding of the properties of {\em all} protons in the nucleus. We propose that this knowledge of the properties of constituent fermions in a correlated many-body system is a unique feature of nuclear physics.Comment: 110 pages, accepted for publication on Prog. Part. Nucl. Phy