Electroweak sector under scrutiny: A combined analysis of LHC and electroweak precision data

Abstract

We perform a comprehensive study of the Higgs couplings, gauge boson couplings to fermions, and triple gauge boson vertices. We work in the framework of effective theories including the effects of the dimension-six operators contributing to these observables. We determine the presently allowed range for the coefficients of these operators via a 20 parameter global fit to the electroweak precision data, as well as electroweak diboson and Higgs production data from LHC runs 1 and 2. We quantify the improvement on the determination of the 20 Wilson coefficients by the inclusion of the run 2 results. In particular, we present a novel analysis of the ATLAS run 2 36.1 fb−1 data on the transverse mass distribution of WþW− and WZ in the leptonic channel, which allows for stronger tests of the triple gauge boson vertices. We discuss the discrete (quasi)degeneracies existing in the parameter space of operator coefficients relevant for the Higgs couplings to fermions and gauge bosons. In particular, we show how the inclusion of the incipient tH data can break those degeneracies in the determination of the top Higgs coupling. We also discuss and quantify the effect of keeping the terms quadratic in the Wilson coefficients in the analysis, and we show the importance of the Higgs data to constrain some of the operators that modify the triple gauge boson couplings in the linear regime.