Irrelevant operators in the two-dimensional Ising model

By using conformal-field theory, we classify the possible irrelevant operators for the Ising model on the square and triangular lattices. We analyze the existing results for the free energy and its derivatives and for the correlation length, showing that they are in agreement with the conformal-field theory predictions. Moreover, these results imply that the nonlinear scaling field of the energy-momentum tensor vanishes at the critical point. Several other peculiar cancellations are explained in terms of a number of general conjectures. We show that all existing results on the square and triangular lattice are consistent with the assumption that only nonzero spin operators are present.Comment: 32 pages. Added comments and reference

Finite-size scaling corrections in two-dimensional Ising and Potts ferromagnets

Finite-size corrections to scaling of critical correlation lengths and free energies of Ising and three-state Potts ferromagnets are analysed by numerical methods, on strips of width $N$ sites of square, triangular and honeycomb lattices. Strong evidence is given that the amplitudes of the ``analytical'' correction terms, $N^{-2}$, are identically zero for triangular-- and honeycomb Ising systems. For Potts spins, our results are broadly consistent with this lattice-dependent pattern of cancellations, though for correlation lengths non-vanishing (albeit rather small) amplitudes cannot be entirely ruled out.Comment: 11 pages, LaTeX with Institute of Physics macros, 2 EPS figures; to appear in Journal of Physics

Global Standards in Action: Insights from Anti-Money Laundering Regulation

As organizations have come under the increasing influence of global rules of all sorts, organization scholars have started studying the dynamics of global regulation. The purpose of this article is to identify and evaluate the contribution to this interdisciplinary field by the ‘Stockholm Centre for Organisational Research’. The latter’s key proposition is that while global regulation often consists of voluntary best practice rules it can nevertheless become highly influential under certain conditions. We assess how innovative this approach is using as a benchmark the state of the art in another field of relevance to the study of global regulation, i.e. ‘International Relations’. Our discussion is primarily theoretical but we draw on the case of global anti-money laundering regulation to illustrate our arguments and for inspirations of how to further elaborate the approach

Exact Finite-Size-Scaling Corrections to the Critical Two-Dimensional Ising Model on a Torus. II. Triangular and hexagonal lattices

We compute the finite-size corrections to the free energy, internal energy and specific heat of the critical two-dimensional spin-1/2 Ising model on a triangular and hexagonal lattices wrapped on a torus. We find the general form of the finite-size corrections to these quantities, as well as explicit formulas for the first coefficients of each expansion. We analyze the implications of these findings on the renormalization-group description of the model.Comment: 45 pages (LaTeX2e). Self-unpacking file containing the tex file and three macros (indent.sty, eqsection.sty, subeqnarray.sty). Paper I corresponds to cond-mat/0009054. Final versio

Bifurcation at the c=3/2 Takhtajan-Babujian point to the c=1 critical lines

We study the S=1 quantum spin chains with bilinear, biquadratic, plus bond alternation in the vicinity of the S=1 Takhtajan-Babujian model. Transition line between the Haldane and the dimer phases are determined numerically. To see the crossover behavior from c=3/2 (k=2 SU(2) WZW model) at the Takhtajan-Babujian point to c=1 (k=1 SU(2) WZW model), we calculate the conformal anomaly c and scaling dimensions of the primary fields on the transition line.Comment: 10 pages, 8 figure

Tricritical Behavior in the Extended Hubbard Chains

Phase diagrams of the one-dimensional extended Hubbard model (including nearest-neighbor interaction $V$) at half- and quarter-filling are studied by observing level crossings of excitation spectra using the exact diagonalization. This method is based on the Tomonaga-Luttinger liquid theory including logarithmic corrections which stem from the renormalization of the Umklapp- and the backward-scattering effects. Using this approach, the phase boundaries are determined with high accuracy, and then the structure of the phase diagram is clarified. At half-filling, the phase diagram consists of two Berezinskii-Kosterlitz-Thouless (BKT) transition lines and one Gaussian transition line in the charge sector, and one spin-gap transition line. This structure reflects the U(1) $\otimes$ SU(2) symmetry of the electron system. Near the $U=2V$ line, the Gaussian and the spin-gap transitions take place independently from the weak- to the intermediate-coupling region, but these two transition lines are coupled in the strong-coupling region. This result demonstrates existence of a tricritical point and a bond-charge-density-wave (BCDW) phase between charge- and spin-density-wave (CDW, SDW) phases. To clarify this mechanism of the transition, we also investigate effect of a correlated hopping term which plays a role to enlarge BCDW and bond-spin-density-wave (BSDW) phases. At quarter-filling, a similar crossover phenomenon also takes place in the large-$V$ region involving spin-gap and BKT-type metal-insulator transitions.Comment: 18 pages(REVTeX), 17 figures(EPS(color)), 3 tables, Detailed paper of JPSJ 68 (1999) 3123 (cond-mat/9903227), see also cond-mat/000341

Expression of the Salmonella Spp. Virulence Factor SifA in Yeast Alters Rho1 Activity on Peroxisomes

SifA is a virulence protein required for assembly and tubulation of a modified phagosome that promotes Salmonella replication. We show that SifA expressed in yeast induces membrane invagination during peroxisome proliferation and requires functional Rho1p. This is consistent with SifA ability to interact with RhoA and the fact that it is a GEF structural homologue