Incollection,
Two-dimensional statistical models away from their integrable lines
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
Abstract
Thanks to integrable quantum field theories, there has been
in recent years new understanding on a large number of models
of interest in statistical mechanics or in condensed
matter physics, e.g. Ising model in a magnetic field or
Sine-Gordon model. Integrability has permitted to determine,
the exact spectrum of the excitations of many systems, the explicit
determination of the correlation functions of their order
parameters, as well as their thermodynamical properties. In
the seminar there will be discussed two methods which permit
to extend this analysis also to non-integrable models: the first
one is based on the Form Factor Perturbation Theory while the
second is based on semi-classical techniques. Both approches will
be illustrated by studying in details the non-integrable
features of a particular significant example, the spectrum
of the excitations (and their decays) in the Ising model by varying
the temperature and the magnetic field.
