10–12 Jun 2019
Catania
Europe/Rome timezone

Surprises in the O(N) models or why might the standard large N analysis fail

12 Jun 2019, 14:25
45m
Catania

Catania

Museo Diocesano Piazza Duomo, Via Etnea, 8 - 95121 Catania

Speaker

Bertrand Delamotte

Description

The O(N) models are probably the most studied field theories. Everything is supposed to be known about their symmetric and symmetry broken phases as well as their critical behavior. Many analytical methods were born here and it is the textbook example for both the $\epsilon=4-d$ and the
large-$N$ expansions. We nevertheless show that several
renormalization group fixed points of this model were not found by the usual methods. These new fixed points are relevant for the multicritical physics of the O(N) models.
We also show that the $N\to\infty$ limit was not
able to identify them because of an implicit analyticity prerequisite of this method that turns out to be wrong. The functional and nonperturbative renormalization group plays a key role to find them.

Presentation materials

There are no materials yet.