丁香园AV

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Synopsis

In this talk, I will present a new tool to constrain low-energy Wilson coefficients in a scalar EFT (scalar for simplicity's sake but the range of applicability is much wider) based on the requirement that such theories should respect causality. Causality will be defined in the sense that no low-energy observer should be able to measure any resolvable time-advance resulting from a scattering event. I will show that these so-called causality bounds are in remarkable agreement with previously derived positivity bounds (where low energy constraints on the 4-point amplitude make use of physical assumptions of the UV completion of the EFT), while being considerably simpler and a better candidate to get cosmological and black hole gravitational bounds.