PIRSA:24060020

Causality Protection in Effective Field Theory

Serra, F. (2024). Causality Protection in Effective Field Theory. Perimeter Institute. https://pirsa.org/24060020

Serra, Francesco. Causality Protection in Effective Field Theory. Perimeter Institute, Jun. 18, 2024, https://pirsa.org/24060020 

          @misc{ pirsa_PIRSA:24060020,
            doi = {10.48660/24060020},
            url = {https://pirsa.org/24060020},
            author = {Serra, Francesco},
            keywords = {Particle Physics},
            language = {en},
            title = {Causality Protection in Effective Field Theory},
            publisher = {Perimeter Institute},
            year = {2024},
            month = {jun},
            note = {PIRSA:24060020 see, \url{https://pirsa.org}}
          }

Francesco Serra

Talk number
PIRSA:24060020
Collection
Talk Type
Subject
Abstract

I discuss how quantum mechanical effects prevent violations of causality in low energy processes, even when faster-than-light propagation is possible. At the classical level, faster-than-light propagation can be used to build "time-machine" configurations that violate causality. However, low-energy quantum excitations propagating on these backgrounds lead to divergent backreaction through loop effects. These divergences fully probe the UV dynamics of the system, making it impossible to prepare and describe causality violating configurations in the regime of validity of effective field theory. In light of these results, I conclude that effective field theories with negative Wilson coefficients or Galileon-symmetric interactions are not in tension with causality, despite leading to faster-than-light propagation.