Centro de Excelencia Severo Ochoa

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The EFT-Hedron

Old Journal Club

Specialist level

Speaker:

Jaime Fernandez Tejedor

Institution:

IFT

Location&Place:

Red Room

Abstract:

Jaime Fernandez Tejedor, con la charla basada en “The EFT-Hedron”, de N. Arkani-Hamed, T.-C. Huang y Y. Huang ( JHEP 05 (2021) 259):

We re-examine the constraints imposed by causality and unitarity on the low-energy effective field theory expansion of four-particle scattering amplitudes, exposing a hidden “totally positive” structure strikingly similar to the positive geometries associated with grassmannians and amplituhedra. This forces the infinite tower of higher-dimension operators to lie inside a new geometry we call the “EFT-hedron”. We initiate a systematic investigation of the boundary structure of the EFT-hedron, giving infinitely many linear and non-linear inequalities that must be satisfied by the EFT expansion in any theory. We illustrate the EFT-hedron geometry and constraints in a wide variety of examples, including new consistency conditions on the scattering amplitudes of photons and gravitons in the real world.