Abstract
We present a novel framework for carrying out global analyses of the Standard Model Effective Field Theory (SMEFT) at dimension-six: SMEFiT. This approach is based on the Monte Carlo replica method for deriving a faithful estimate of the experimental and theoretical uncertainties and enables one to construct the probability distribution in the space of the SMEFT degrees of freedom. As a proof of concept of the SMEFiT methodology, we present a first study of the constraints on the SMEFT provided by top quark production measurements from the LHC. Our analysis includes more than 30 independent measurements from 10 different processes at sqrt{s} = 8 and 13 TeV such as inclusive toverline{t} and single-top production and the associated production of top quarks with weak vector bosons and the Higgs boson. State-of-the-art theoretical calculations are adopted both for the Standard Model and for the SMEFT contributions, where in the latter case NLO QCD corrections are included for the majority of processes. We derive bounds for the 34 degrees of freedom relevant for the interpretation of the LHC top quark data and compare these bounds with previously reported constraints. Our study illustrates the significant potential of LHC precision measurements to constrain physics beyond the Standard Model in a model-independent way, and paves the way towards a global analysis of the SMEFT.
Highlights
Model Effective Field Theory (SMEFT) at dimension-six: SMEFiT
We report the values of the 95% confidence level bounds for the coefficients of the 34 Standard Model Effective Field Theory (SMEFT) degrees of freedom derived from the marginalisation of the results of the SMEFiT global analysis
In this work we have presented a novel approach to carry out global analyses of the SMEFT
Summary
We describe the theoretical formalism that will be adopted in this work to interpret the LHC top quark production data within the SMEFT framework. We provide an introduction to the SMEFT, focusing on those operators that affect the description of the top quark sector. We define the degrees of freedom that are more relevant to studying top quark production at the LHC. Operators that do not involve top quarks and their constraints are briefly discussed. We describe our theory calculations at NLO QCD accuracy, and comment on some additional aspects of the SMEFT formalism relevant for this study
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