  Electroweak precision observables (EWPO) measured at the W and Z poles
provide stringent limits on possible beyond the Standard Model physics
scenarios. In an effective field theory (EFT) framework, the next-to-leading
order QCD and electroweak results for EWPO yield indirect limits on possible
4-fermion operators that do not contribute to the observables at tree level.
Here we calculate the next-to-leading corrections to EWPO induced by flavor
non-universal 4-fermion interactions and find that the extracted limits on EFT
coefficients have a strong dependence on the flavor structure of the 4-fermion
operators.
