Author:
Antonov E. N.,Orlov A. Yu.
Abstract
The generating series for the instanton contribution to Green functions of
the $2D$ sigma model was found in the works of Schwarz, Fateev and Frolov. We
show that this series can be written as a formal tau function of the two-sided
two-component KP hierarchy. We call it formal singular tau function because
this tau function is a sum where each term is the infrared and ultraviolet
divergent one exactly as the series found by the mentioned authors. However one
can regularize this singluar tau function and to obtain regular observables.
This is because observables contains ratious of mentioned divergent
expressions. Thus, we enladge the families of tau functions to work with.
Publisher
Centre pour la Communication Scientifique Directe (CCSD)
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