EWPD in the SMEFT and the mathcal{O}(y_t²,λ) one loop Z decay width

The interpretation of electroweak precision data in the Standard Model Effective Field Theory is discussed. One loop corrections $\propto y_t^2, \lambda$ to the partial $Z$ decay widths and ratios of partial widths in this theory are discussed. A reparameterization invariance and the non-minimal character of matching onto this theory is reviewed.