Integrable quantum field theory

Home page of Dr. Benjamin Doyon



This is a short series of lectures on integrable quantum field theory in the Spring term of 2008 (Durham University), see the list of graduate lectures. Integrable quantum field theory is a wide subject with applications, for instance, to condensed matter and statistical physics, and with many connections to diverse areas of mathematics. It offers the unique opportunity to probe the properties of quantum field theory, both as a theory of relativistic particles and as a scaling limit of quantum chains and classical lattice systems, in a much deeper way than what can be done from standard methods. Knowing some of integrable quantum field theory also provides many useful tools for theoretical physicists, and gives a wider understanding of objects of interest to mathematicians.

I will aim my lectures at graduate students and advanced undergraduates. The course is intended to be an introduction to both quantum field theory, and integrability in this context. As an introduction to quantum field theory, it complements and does not replace standard courses, since the emphasis will be on the general structure and non-perturbative aspects.

I will assume knowledge of:

  • Quantum mechanics
  • Special relativity
  • Complex analysis
There will be 4 lectures, for a total of 6 hours. Lectures are in OC218 (Ogden Centre), at the following dates and times:
  • 29 April, 9:00 - 11:00
  • 1 May, 11:00 - 13:00
  • 5 May, 15:15 - 16:15
  • 6 May, 12:00 - 13:00



Lecture notes  (updated regularly)



There are many aspects to integrable quantum field theory. The course will focus mainly on what is called factorised scattering theory, which is applicable when there is a scale in the model, more precisely for quantum models of massive relativistic particles.

Plan:
  • Main ideas behind integrability. What is quantum field theory, and its main concepts: asymptotic states and the scattering matrix, local fields and the operator product expansion, correlation functions.
  • Short distances and large distances: the renormalisation group flow and correlation functions.
  • Local conserved charges. Factorisation of the scattering matrix, analytic properties and the Yang-Baxter equation. Exact solutions.
  • Properties of form factors: a Riemann-Hilbert problem that can be solved exactly. Evaluation of correlation functions. Twist fields.
  • Other topics (as time permits): Bethe ansatz; conformal perturbation theory; integrable differential equations from quantum field theory.



Reading (reviews, theses):
  • P. Dorey, Exact S-matrices, preprint hep-th/9810026.
  • F. H. L. Essler, R. M. Konik, Applications of Massive Integrable Quantum
    Field Theories to Problems in Condensed Matter Physics. I. Kogan Memorial
    Volume, World Scientific, preprint cond-mat/0412421
  • G. Mussardo, Off-critical statistical models: Factorized scattering theories
    and bootstrap program. Phys. Rep. 218 (1992) 215-379
  • O. A. Castro Alvaredo, Bootstrap methods in 1+1 dimensional quantum field
    theory: the homogeneous sine-Gordon models. Universidade de Santiago de
    Compostela, Spain (2001) hep-th/0109212
  • B. D., Correlation functions in integrable quantum field theory. Rutgers
    University, USA (2004) .ps, .pdf
More reading (fundamental works):
  • A. B. Zamolodchikov and Al. B. Zamolodchikov, Factorized S-matrices in
    two dimensions as the exact solutions of certain relativistic quantum field
    theory models, Ann. Phys. 120 (1979) 253-291.
  • M. Karowski and P. Weisz, Exact form factors in (1+1)-dimensional field
    theoretic models with soliton behaviour. Nucl. Phys. B139 (1978) 455-476.
  • F. A. Smirnov, Form factors in completely integrable models of quantum
    field theory, World Scientific, Singapore (1992).