Abstract
We show that, for two nontrivial problems (the anharmonic oscillator and the Landau-Ginzburg hierarchical model), improved perturbative series can be obtained by cutting off the large field contributions. The modified series converge to values exponentially close to the exact ones. For larger than some critical value, the method outperforms Padé’s approximants and Borel summations. The method can also be used for series which are not Borel summable such as the double-well potential series. We show that semiclassical methods can be used to calculate the modified Feynman rules, estimate the error, and optimize the field cutoff.
- Received 16 March 2001
DOI:https://doi.org/10.1103/PhysRevLett.88.141601
©2002 American Physical Society