An Isotropic Prescription for Constructing the SMEFT in Normal Coordinates to Simplify Amplitude Computations

by Mia West (University of Florida)

Friday 16 Jan 2026, 13:00 → 14:00 Europe/London

Bohr conference room

Geometry provides us with a convenient interpretation of field-redefinition invariance for amplitudes and has many useful properties. For instance, it directs us towards Riemann Normal Coordinates (RNC) as an ideal choice of field-redefinition to compute amplitudes. It has been shown in the Higgs Effective Field Theory (HEFT) assuming custodial symmetry & in the high-energy limit in RNC there are distinct kinematics for each Feynman graph. Redefining the Lagrangian in these coordinates appears to generate a reduced set of Feynman graphs which still sum to the correct amplitude. This property also holds in the Standard Model EFT (SMEFT) as a subset of HEFT. In this talk, we will demonstrate a prescription to construct the SMEFT in RNC around the symmetric point using isotropy, applicable to all orders in the SMEFT expansion. Then, breaking electroweak symmetry corresponds to traversing a geodesic to the vacuum and re-establishing RNC in terms of isotropic properties of the symmetric point. We argue that this prescription is simpler compared to the usual recursive method to construct RNC.