Shift-Type SMEFT Effects in Dileptons at the LHC

TL;DR

This paper analyzes how dilepton production at the LHC constrains SMEFT Wilson coefficients, including shift effects, providing new bounds that complement existing LEP and LHC constraints with robust theoretical error estimates.

Contribution

It introduces a comprehensive analysis of dilepton constraints on SMEFT Wilson coefficients, including shift effects and higher-order theory errors, offering new independent bounds.

Findings

Constraints on energy-growing four-fermion operators remain strong.

Bounds on shift operators are comparable to LEP constraints.

New independent constraints complement existing LHC and LEP bounds.

Abstract

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.