LHC EFT WG Report: Experimental Measurements and Observables

Abstract

The LHC effective field theory working group gathers members of the LHC experiments and the theory community to provide a framework for the interpretation of LHC data in the context of EFT. In this note we discuss experimental observables and corresponding measurements in analysis of the Higgs, top, and electroweak data at the LHC. We review the relationship between operators and measurements relevant for the interpretation of experimental data in the context of a global SMEFT analysis. One of the goals of ongoing effort is bridging the gap between theory and experimental communities working on EFT, and in particular concerning optimised analyses. This note serves as a guide to experimental measurements and observables leading to EFT fits and establishes good practice, but does not present authoritative guidelines how those measurements should be performed.

SMEFiT: a flexible toolbox for global interpretations of particle physics data with effective field theories

“…Whenever possible, these analyses strived to account for NLO QCD calculations in the EFT cross-sections such as those provided by the SMEFT@NLO package [18]. Additional studies based on SMEFiT are the implementation of the Bayesian reweighting method [19] and the LHC EFT WG report on experimental observables [20]. Advantages of SMEFiT as compared to related frameworks include independent and complementary statistical methods to carry out parameter inference (Monte Carlo optimisation and Nested Sampling), the lack of restrictions on the allowed functional dependence in c i /Λ 2 for the fitted observables, and a competitive scaling of the running time with the number of fitted parameters.…”