Functional differential equation approach to the large N expansion and mean field perturbation theory
✍ Scribed by Carl M Bender; Fred Cooper
- Publisher
- Elsevier Science
- Year
- 1985
- Tongue
- English
- Weight
- 745 KB
- Volume
- 160
- Category
- Article
- ISSN
- 0003-4916
No coin nor oath required. For personal study only.
✦ Synopsis
An apparent difference between formulating mean field perturbation theory for @* field theory via path integrals or via functional differential equations when there are external sources present is shown not to exist when mean lield theory is considered as the N= 1 limit of the O(N) @" field theory. A simple method is given for determining the l/N expansion for the Green's functions in the presence of external sources by directly solving the functional differential equations order by order in l/N. The l/N expansion for the effective action r(& 1) is obtained by directly integrating the functional differential equations for the fields 4 and x