Abstract

We explore the interplay of New Physics (NP) effects in (g− 2)ℓ and h→ℓ+ℓ− within the Standard Model Effective Field Theory (SMEFT) framework, including one-loop Renormalization Group (RG) evolution of the Wilson coefficients as well as matching to the observables below the electroweak symmetry breaking scale. We include both the leading dimension six chirality flipping operators including a Higgs and SU(2)L gauge bosons as well as four-fermion scalar and tensor operators, forming a closed operator set under the SMEFT RG equations. We compare present and future experimental sensitivity to different representative benchmark scenarios. We also consider two simple UV completions, a Two Higgs Doublet Model and a single scalar LeptoQuark extension of the SM, and show how tree level matching to SMEFT followed by the one-loop RG evolution down to the electroweak scale can reproduce with high accuracy the (g−2)ℓ and h→ℓ+ℓ− contributions obtained by the complete one- and even two-loop calculations in the full models.

Highlights

  • We explore the interplay of New Physics (NP) effects in (g − 2) and h → + − within the Standard Model Effective Field Theory (SMEFT) framework, including one-loop Renormalization Group (RG) evolution of the Wilson coefficients as well as matching to the observables below the electroweak symmetry breaking scale

  • We consider two simple UV completions, a Two Higgs Doublet Model and a single scalar LeptoQuark extension of the SM, and show how tree level matching to SMEFT followed by the one-loop RG evolution down to the electroweak scale can reproduce with high accuracy the (g−2) and h → + − contributions obtained by the complete one- and even two-loop calculations in the full models

  • In this paper we examined New Physics effects in charged lepton anomalous magnetic moments and Higgs decays to charged lepton pairs within the SMEFT framework

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Summary

SMEFT operator basis

To form a closed set of RG equations, we need to take into account the RG evolution of gauge and Yukawa couplings. We consider the cases where the UV complete model generates one operator for a specific flavor at the leading EW order, while all the others are EW loop-induced. C2, and C3, can induce a sizeble C1, through their RG evolution It follows that bounds on leptonic Higgs decays become relevant for these models, together with bounds on the lepton anomalous magnetic moments, which O2, and O3, generate at the leading order when matched to the low energy EFT below the EW scale (see section for details). The two four-fermion operators O4, and O5, are able to induce C1, , C2, and C3, , in very different proportions

Operator matching to observables below EWSB
Higgs decay to two leptons
Anomalous magnetic moment
Phenomenology
Electron
Flavor specific 2HDM
Model description
Phenomenology: full 2HDM vs SMEFT
Scalar LeptoQuarks
Conclusions
B Details on one-loop diagram calculations in SMEFT
Findings
C Power expansion of two-loop Bar-Zee diagrams
Full Text
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