Speaker
Description
In the bottom-up approach to Effective Field Theory (EFT), we systematically construct the most general Lagrangian by writing all operators allowed by the symmetries of the system, each multiplied by an arbitrary Wilson coefficient. For instance, in the case of a scalar field with shift symmetry, this procedure leads to an infinite tower of derivative interactions. However, not all such EFTs admit a consistent ultraviolet (UV) completion. By imposing fundamental principles such as causality, unitarity, locality, and Lorentz invariance, we obtain powerful constraints on the allowed values of Wilson coefficients. These constraints carve out a nontrivial geometric region in the space of EFT parameters—known as the EFT-hedron. Interestingly, when full unitarity is imposed, this geometry exhibits a non-projective structure, revealing deep connections between low-energy EFT data and high-energy consistency conditions. This presentation explores the construction of EFTs, the geometric nature of the allowed Wilson coefficient space, and how the EFT-hedron emerges as a manifestation of fundamental physical principles.
