Critical Phenomena In Loop Models

When close to a continuous phase transition, many physical systems can usefully be mapped to ensembles of fluctuating loops, which might represent for example polymer rings, or line defects in a lattice magnet, or worldlines of quantum particles. 'Loop models' provide a unifying geometric language for problems of this kind. This thesis aims to extend this language in two directions. The first part of the thesis tackles ensembles of loops in three dimensions, and relates them to the statistical properties of line defects in disordered media and to critical phenomena in two-dimensional quantum magnets. The second part concerns two-dimensional loop models that lie outside the standard paradigms: new types of critical point are found, and new results given for the universal properties of polymer collapse transitions in two dimensions. All of these problems are shown to be related to sigma models on complex or real projective space, CP^{n−1} or RP^{n−1} -- in some cases in a 'replica' limit -- and this thesis is also an in-depth investigation of critical behaviour in these field theories.

This book contains the proceedings of two international conferences: a satellite meeting of the IUPAP Statphys-19 Conference and the Seventh Nankai Workshop, held in Tianjin, China in August 1995. The central theme of the two conferences, which drew participants from 18 countries, was the Yang–Baxter equation and its development and applications. With topics ranging from quantum groups, vertex and spin models, to applications in condensed matter physics, this book reflects the current research interest of integrable systems in statistical mechanics. Contents:Satellite Meeting of Statphys-19:Boundary Yang–Baxter in the RSOS/SOS Representation (C Ahn & W M Koo)Quantum Domains in Ferromagnetic Anisotropic Heisenberg Chains (F C Alcaraz et al.)The Generalized Chiral Clock Model and Its Phase Diagram (H Au-Yang & J H H Perk)Algebraic Solution of the Coincidence Problem for Crystals and Quasicrystals (M Baake)Reflection Equations and Surface Critical Phenomena (M T Batchelor)Quantum Field Theories in Terms of Group-Valued Local Fields: An Overview (L-L Chau)U(1)-Invariant Local and Integrable Lattice Formulation of the Massive Thirring Model (C Destri)Dilute Algebras and Solvable Lattice Models (U Grimm)Mutual Exclusion Statistics in the Exactly Solvable Model of the Mott Metal-Insulator Transition (Y Hatsugai et al.) Quantum Group and the Hofstadter Problem (Y Hatsugai et al.)Domain Walls in the Spin-S Quantum Ising Chain (M Henkel)Probability of Phase Separation and Two Point Temperature Correlation Functions for the Bose Gas with Delta Interaction (A R Its & V E Korepin)Stochastic Reaction-Diffusion Processes, Operator Algebras and Integrable Quantum Spin Chains (G M Schütz)Vertex-Face Correspondence in Elliptic Solutions of the Yang–Baxter Equation (Y Shibukawa)Logarithmic Anomalies of Susceptibility for Solvable Models (M Takahashi)On Chiral Hubbard Model at Strong Interaction (D F Wang)Soluble Free-Fermion Models in d Dimensions (F Y Wu)Bosonization Based on Bethe Ansatz Equations and Proof of the Conformal Conjecture (Y-S Wu & Y Yu)and other papersThe Seventh Nankai Workshop:Corner Transfer Matrix of Asymmetric Vertex Models (H-P Eckle)Scaling Properties of the Ising Model in a Field (U Grimm & B Nienhuis)One Dimensional Lattice Models of Electrons with r–2 Hopping and Exchange (Ch Gruber & D F Wang)Symmetry Group Invariants for Spontaneous Magnetization (J-M Maillard)Experimental Realizations of Integrable Reaction-Diffusion Processes in Biological and Chemical Systems (G M Schütz)Zamolodchikov–Faddeev Algebra in 2-Component Anyons (Y-L Shen & M-L Ge)and other papers Readership: Theoretical physicists and mathematicians. keywords:

This book lays the foundations of the theory of fluctuating multivalued fields with numerous applications. Most prominent among these are phenomena dominated by the statistical mechanics of line-like objects, such as the phase transitions in superfluids and superconductors as well as the melting process of crystals, and the electromagnetic potential as a multivalued field that can produce a condensate of magnetic monopoles. In addition, multivalued mappings play a crucial role in deriving the physical laws of matter coupled to gauge fields and gravity with torsion from the laws of free matter. Through careful analysis of each of these applications, the book thus provides students and researchers with supplementary reading material for graduate courses on phase transitions, quantum field theory, gravitational physics, and differential geometry.

This volume contains the proceedings of the conference on 'Exactly Soluble Models in Statistical Mechanics: Historical Perspectives and Current Status', held at Northeastern University in March 1996 — the first ever conference to deal exclusively with this topic. Besides invited presentations by leading researchers in the field, the conference held a session of contributed papers by participants from throughout the world. The proceedings, which include both the invited and the contributed papers, reflect the broad range of interest in exactly soluble models as well as the diverse fields in physics and mathematics that they connect. Apart from providing concise and timely reviews, the papers in this volume give a snapshot of the current state of affairs. The topics covered range from a historical survey of the field (by E H Lieb) to the latest formulation of a star-star transformation of spin models (by R J Baxter).

Concepts, methods and techniques of statistical physics in the study of correlated, as well as uncorrelated, phenomena are being applied ever increasingly in the natural sciences, biology and economics in an attempt to understand and model the large variability and risks of phenomena. This is the first textbook written by a well-known expert that provides a modern up-to-date introduction for workers outside statistical physics.

The problem of counting the number of self-avoiding polygons on a square grid, - therbytheirperimeterortheirenclosedarea,is aproblemthatis soeasytostate that, at ?rst sight, it seems surprising that it hasn’t been solved. It is however perhaps the simplest member of a large class of such problems that have resisted all attempts at their exact solution. These are all problems that are easy to state and look as if they should be solvable. They include percolation, in its various forms, the Ising model of ferromagnetism, polyomino enumeration, Potts models and many others. These models are of intrinsic interest to mathematicians and mathematical physicists, but can also be applied to many other areas, including economics, the social sciences, the biological sciences and even to traf?c models. It is the widespread applicab- ity of these models to interesting phenomena that makes them so deserving of our attention. Here however we restrict our attention to the mathematical aspects. Here we are concerned with collecting together most of what is known about polygons, and the closely related problems of polyominoes. We describe what is known, taking care to distinguish between what has been proved, and what is c- tainlytrue,but has notbeenproved. Theearlierchaptersfocusonwhatis knownand on why the problems have not been solved, culminating in a proof of unsolvability, in a certain sense. The next chapters describe a range of numerical and theoretical methods and tools for extracting as much information about the problem as possible, in some cases permittingexactconjecturesto be made.

The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies. Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations. The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable information on important recent developments.

Conformal invariance has been a spectacularly successful tool in advancing our understanding of the two-dimensional phase transitions found in classical systems at equilibrium. This volume sharpens our picture of the applications of conformal invariance, introducing non-local observables such as loops and interfaces before explaining how they arise in specific physical contexts. It then shows how to use conformal invariance to determine their properties. Moving on to cover key conceptual developments in conformal invariance, the book devotes much of its space to stochastic Loewner evolution (SLE), detailing SLE’s conceptual foundations as well as extensive numerical tests. The chapters then elucidate SLE’s use in geometric phase transitions such as percolation or polymer systems, paying particular attention to surface effects. As clear and accessible as it is authoritative, this publication is as suitable for non-specialist readers and graduate students alike.