Correlating uncertainties in global analyses within standard model EFT matters

201

167

The search for effective field theory deformations of the Standard Model (SM) is a major goal of particle physics that can benefit from a global approach in the framework of the Standard Model Effective Field Theory (SMEFT). For the first time, we include LHC data on top production and differential distributions together with Higgs production and decay rates and Simplified Template Cross-Section (STXS) measurements in a global fit, as well as precision electroweak and diboson measurements from LEP and the LHC, in a global analysis with SMEFT operators of dimension 6 included linearly. We present the constraints on the coefficients of these operators, both individually and when marginalised, in flavour-universal and top-specific scenarios, studying the interplay of these datasets and the correlations they induce in the SMEFT. We then explore the constraints that our linear SMEFT analysis imposes on specific ultra-violet completions of the Standard Model, including those with single additional fields and low-mass stop squarks. We also present a model-independent search for deformations of the SM that contribute to between two and five SMEFT operator coefficients. In no case do we find any significant evidence for physics beyond the SM. Our underlying Fitmaker public code provides a framework for future generalisations of our analysis, including a quadratic treatment of dimension-6 operators.

“…We note that global SMEFT fits would benefit greatly from a future Z-pole run[193][194][195] 7. See ref [198]. for a study of the impact of correlations in global fits.…”

mentioning

confidence: 95%

Top, Higgs, diboson and electroweak fit to the Standard Model effective field theory

Ellis

Madigan

Mimasu

et al. 2021

201

167

“…BSM contributions are parametrized as in (3.1), which includes quadratic dimensionsix terms. While these purely BSM contributions are formally of higher order in the EFT expansion, O(Λ −4 ), it has been shown [12,49] that the inclusion of such quadratic terms has only a negligible effect on constraints of coefficients for which the linear term in the EFT expansion gives the dominant contribution, as expected in regions where the EFT is valid.…”

Section: Fits To Present Datamentioning

confidence: 94%

“…For 1 Differential cross sections on the other hand are sensitive to four-fermion contributions [16]. Since bin-to-bin correlations are not available, yet important [49], we do not consider such observables in our fit.…”

Section: Flavor and Mass Basismentioning

confidence: 99%

Top and beauty synergies in SMEFT-fits at present and future colliders

Bißmann

Grunwald

Hiller

et al. 2021

Self Cite

We perform global fits within Standard Model Effective Field Theory (SMEFT) combining top-quark pair production processes and decay with b → s flavor changing neutral current transitions and Z → $$ b\overline{b} $$ b b ¯ in three stages: using existing data from the LHC and B-factories, using projections for the HL-LHC and Belle II, and studying the additional new physics impact from a future lepton collider. The latter is ideally suited to directly probe ℓ+ℓ− → $$ t\overline{t} $$ t t ¯ transitions. We observe powerful synergies in combining both top and beauty observables as flat directions are removed and more operators can be probed. We find that a future lepton collider significantly enhances this interplay and qualitatively improves global SMEFT fits.

“…To date, this principle has been applied within individual sectors as well as across Higgs, electroweak (EW) and top quark measurements, see refs. [5][6][7][8][9][10][11][12][13][14][15] for recent examples. The incorporation of data from flavor observables (including non-LHC experiments) would be very valuable in this context, as most of the SMEFT parameter space is "flavorful".…”

Section: Introductionmentioning

confidence: 99%

“…This includes contributions from the square of a diagram with one EFT insertion, as well as from the interference between SM and EFT diagrams with two EFT vertices, or EFT diagrams with a single interaction ∝ C 2 . The latter generally stem from field or parameter redefinitions in the Lagrangian 11. Ref [63].…”

mentioning

confidence: 99%

SMEFTsim 3.0 — a practical guide

Brivio¹

2021

The SMEFTsim package [1] is designed to enable automated computations in the Standard Model Effective Field Theory (SMEFT), where the SM Lagrangian is extended with a complete basis of dimension six operators. It contains a set of models written in FeynRules and pre-exported to the UFO format, for usage within Monte Carlo event generators. The models differ in the flavor assumptions and in the input parameters chosen for the electroweak sector. The present document provides a self-contained, pedagogical reference that collects all the theoretical and technical aspects relevant to the use of SMEFTsim and it documents the release of version 3.0. Compared to the previous release, the description of Higgs production via gluon-fusion in the SM has been significantly improved, two flavor assumptions for studies in the top quark sector have been added, and a new feature has been implemented, that enables the treatment of linearized SMEFT corrections to the propagators of unstable particles.SMEFTsim 3.0 is available on the Github website https://SMEFTsim.github.io and on the FeynRules database http://feynrules.irmp.ucl.ac.be/wiki/SMEFT.