Café com Física
Wojtek J. Zakrzewski
Department of Mathematical Sciences, University of Durham
Some Comments on quasi-integrability
In this talk I will mention several ideas that Luiz Ferreira and I had on how to define the concept of quasintegrability. This is due to the observation that many field-theory models are 'almost' integrable, i.e., possess a large number of 'almost' conserved quantities. I will base my discussion on a class of models which generalize the Sine-Gordon model in 1+1 dimensions. I will show that many field configurations of these models look like those of the integrable systems and others are very close to being integrable. I will then attempt to quantify these claims looking in particular, both analytically and numerically, at some long lived field configurations which resemble breathers.