Updated global SMEFT fit to Higgs, diboson and electroweak data

Abstract

The ATLAS and CMS collaborations have recently released significant new data on Higgs and diboson production in LHC Run 2. Measurements of Higgs properties have improved in many channels, while kinematic information for h → γγ and h → ZZ can now be more accurately incorporated in fits using the STXS method, and W + W − diboson production at high p T gives new sensitivity to deviations from the Standard Model. We have performed an updated global fit to precision electroweak data, W + W − measurements at LEP, and Higgs and diboson data from Runs 1 and 2 of the LHC in the framework of the Standard Model Effective Field Theory (SMEFT), allowing all coefficients to vary across the combined dataset, and present the results in both the Warsaw and SILH operator bases. We exhibit the improvement in the constraints on operator coefficients provided by the LHC Run 2 data, and discuss the correlations between them. We also explore the constraints our fit results impose on several models of physics beyond the Standard Model, including models that contribute to the operator coefficients at the tree level and stops in the MSSM that contribute via loops.

O new physics, where art thou? A global search in the top sector

“…where σ SM is the SM prediction, σ k are contributions arising from the interference of a single dimension-6 operator with the SM, and σ kl arise from the interference of two rate measurements or the total cross section, because they offer the best statistics and often minimize theoretical uncertainties. From global Higgs-electroweak analyses we know that a modified momentum dependence can be constrained most efficiently by high-energy tails of kinematic distributions or simplified template cross sections [8][9][10][11][12][13]. † Similarly, we know that for many kinematic distributions the few bins with the highest momentum transfer include the relevant information on individual operators, whereas for several operators with a different high-energy behavior there often exist several relevant regimes [104].…”

“…This is essential for the top-pair side of the analysis. Its unique challenges are very different from the electroweak-Higgs sector [8,[10][11][12] and the single top sector discussed in Sec. 5.…”

“…Part of the SMEFT framework [1][2][3][4][5] was developed as a gauge-invariant description of anomalous gauge boson interactions at LEP [6,7]. Its biggest success has been the application to Higgs and electroweak boson measurements at the LHC [8][9][10][11][12][13]. Most recently, the same approach [14][15][16] has been used to systematically analyze top quark measurements at the LHC [17][18][19][20][21] and at future colliders [22,23] and their link to bottom sector [24].…”

Electroweak and QCD corrections to Z and W pole observables in the standard model EFT

“…Numerous studies have been performed extracting limits on the coefficients of dimension-6 operators from global fits to Higgs measurements, vector boson pair production, electroweak measurements at the Z and W poles, top quark measurements, and low energy data [3][4][5][6][7][8][9][10].…”

Flavourful SMEFT likelihood for Higgs and electroweak data

“…A straightforward observation is that SMEFT operators may simultaneously affect both Higgs and electroweak observables. Therefore it makes sense to combine the two sets in order to increase the constraining power of data [6][7][8][9][10][11][12][13][14][15][16]. This work represents another step forward in this direction.In this paper we construct a likelihood for Wilson coefficients of dimension-6 SMEFT operators using a large set of Higgs and electroweak observables.…”