  We explore the constraints which can be derived on Wilson coefficients in the
Standard Model Effective Field Theory from dilepton production, notably
including the constraints on operators which do not lead to cross sections
growing with energy relative to the Standard Model rate, i.e. shifts. We
incorporate essential theory error estimates from higher EFT orders in the
analysis in order to provide robust bounds. We find that constraints on
four-fermion operator contributions which do grow with energy are not
materially weakened by the inclusion of these shifts, and that a constraint on
the shifts can also be derived, with a characteristic strength comparable to,
and a directionality in parameter space complementary to, those from LEP data.
This completes the study of hadronically-quiet dilepton production in the
SMEFT, and provides two new constraints which are linearly independent from
others arising at the LHC and also rotated in Wilson coefficient space relative
to, though not completely independent from, the LEP bounds.
