#### Kick-off event: Wednesday, November 6 afternoon at Institut Henri PoincarĂ©

Infos and registration: https://indico.math.cnrs.fr/e/NTQFTMR

# Spontaneous symmetry breaking on surface defects

*by*

### Gabriel Cuomo

**Abstract:**

Colemanâ€™s theorem states that continuous internal symmetries cannot be spontaneously broken in two-dimensional quantum field theories (QFTs). I will discuss under which conditions a similar result holds for two-dimensional defects in CFTs invariant under a continuous symmetry group. I will argue that spontaneous symmetry breaking is only possible for exotic RG flows, that do not terminate at a fixed point. I will present examples and describe a generic defect universality class, formerly found by Metlitski for boundaries in the O(N) model, where correlation functions decay logarithmically at large distances.

All talks Fall '24: New trends in QFT, modularity, resurgence