Abstract

We explore the implications of the Standard Model effective field theory (SMEFT) with dimension-six terms involving the Higgs boson and third-generation fermion fields on the rate of Higgs boson production and decay into fermions, on the electric dipole moments (EDMs) of the electron, and on the baryon asymmetry of the Universe. We study the consequences of allowing these additional terms for each flavor separately and for combinations of two flavors. We find that a complex τ Yukawa coupling can account for the observed baryon asymmetry {Y}_B^{mathrm{obs}} within current LHC and EDM bounds. A complex b (t) Yukawa coupling can account for 4% (2%) of {Y}_B^{mathrm{obs}} , whereas a combination of the two can reach 12%. Combining τ with either t or b enlarges the viable parameter space owing to cancellations in the EDM and in either Higgs production times decay or the total Higgs width, respectively. Interestingly, in such a scenario there exists a region in parameter space where the SMEFT contributions to the electron EDM cancel and collider signal strengths are precisely SM-like, while producing sufficient baryon asymmetry. Measuring C P violation in Higgs decays to τ leptons is the smoking gun for this scenario.

Highlights

  • The first decade of the LHC experiments led to significant progress in our understanding of Nature

  • We explore the implications of the Standard Model effective field theory (SMEFT) with dimension-six terms involving the Higgs boson and third-generation fermion fields on the rate of Higgs boson production and decay into fermions, on the electric dipole moments (EDMs) of the electron, and on the baryon asymmetry of the Universe

  • We studied in detail aspects of CP violation in the SMEFT

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Summary

Introduction

The first decade of the LHC experiments led to significant progress in our understanding of Nature. No other new elementary particles have been discovered, with lower bounds on the mass of large classes of such hypothetical particles at the TeV scale [9, 10] This situation makes it plausible that the scale of new physics is high enough above the electroweak scale that its effects can be parameterized via higher-dimension operators, and motivates an interpretation of experimental results in the framework of the Standard Model effective field theory (SMEFT). We are interested in dimension-six operators [11, 12] that couple the Higgs boson field to fermion fields The presence of these additional terms provides two important features: novel CP -violating interactions [13] and violation of the SM relation between the fermion mass and its Yukawa coupling.

Dimension-six complex Yukawa terms
The baryon asymmetry YB
Particle dynamics
Impact of TR and TI
The electron EDM de
Higgs production and decay
Signal strength
Production rates
The total Higgs width
Single-flavor modification
Two-flavor modification
Single flavor modification
Two flavor modification
Conclusions
Experimental bounds
B Benchmark values for baryogenesis calculations
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