Speaker
Prof.
Margaret Carrington
(Brandon University)
Description
Non-perturbative techniques are needed to study strongly coupled systems.
One popular method is the 2 particle irreducible (2pi) effective theory.
For scalar theories, calculations at the 3 loop level show improved convergence, relative to perturbative results.
We present results in $\phi^4$ theory at the 4 loop level which show that convergence breaks down at large coupling.
This indicates the need for higher order effective theories.
4pi calculations in 4 dimensions have never been attempted, because no method is known to deal with the overlapping sub-divergences that appear in these theories. We present a new technique to renormalize the 4pi effective theory, based on a renormalization group approach.
Author
Prof.
Margaret Carrington
(Brandon University)
