What is an instanton correction?

[yyoon@fas.harvard.edu]

I know what an instanton is, but do not know what an instanton
correction is.
Could somebody tell me what an instanton correction is, or give me
references?

Thanks in advance

Youngsub

[Igor Khavkine]

On Jun 17, 10:31 am, yy...@fas.harvard.edu wrote:
> I know what an instanton is, but do not know what an instanton
> correction is.
> Could somebody tell me what an instanton correction is, or give me
> references?

Consider any quantity in QFT computed perturbatively, usually a
correlation function expanded as a power series in a coupling. The
perturbative series is often known to be only asymptotic. That is, the
quantity of interest may not be analytic near zero coupling. If the
coupling constant is g, a full expansion may contain terms of the form
exp(-1/g). These terms cannot be obtained in any order in perturbation
theory and require special techniques to calculate. One such technique
is to compute instanton contributions to the path integral, hence the
name instanton corrections.

Unfortunately, I can't give precise references. However, I think that
some of the path integral heavy introductions may devote some time to
instantons. You may want to check out the following:

Ramond, _Field Theory: A Modern Primer_
Zee, _Quantum Field Theory in a Nutshell_
Zinn-Justin, _Quantum Field Theory and Critical Phenomena_

Hope this helps.

Igor

[torre@cc.usu.edu]

A good reference is "Solitons and Instantons",
by R. Rajaraman.

charlie torre