Abstract
We analyze heavy states from generic ultraviolet completions of the Standard Model in a model-independent way and investigate their implications on the low-energy couplings of the electroweak effective theory. We build a general effective Lagrangian, implementing the electroweak symmetry breaking SU(2)L ⊗ SU(2)R → SU(2)L+R with a non-linear Nambu-Goldstone realization, which couples the known particles to the heavy states. We generalize the formalism developed in previous works [1, 2] to include colored resonances, both of bosonic and fermionic type. We study bosonic heavy states with JP = 0± and JP = 1±, in singlet or triplet SU(2)L+R representations and in singlet or octet representations of SU(3)C , and fermionic resonances with J=frac{1}{2} that are electroweak doublets and QCD triplets or singlets. Integrating out the heavy scales, we determine the complete pattern of low-energy couplings at the lowest non-trivial order. Some specific types of (strongly- and weakly-coupled) ultraviolet completions are discussed to illustrate the generality of our approach and to make contact with current experimental searches.
Highlights
The first years of physics runs at the LHC confirmed that the Standard Model (SM) describes the physics at the electroweak (EW) scale very well
The EW effective theory (EWET) is the most general effective field theories (EFTs) framework incorporating the known particle states and the SM symmetries. It is based on the successful pattern of electroweak symmetry breaking
The Higgs boson is parametrized as a light neutral scalar h, singlet under the electroweak group, and a non-linear realization of the
Summary
The first years of physics runs at the LHC confirmed that the Standard Model (SM) describes the physics at the electroweak (EW) scale very well. With an SU(2)L doublet structure at the electroweak scale, the resulting EFT is an expansion in canonical dimensions that is called SM effective theory (SMEFT). It usually describes weakly coupled new physics that decouples from the SM in a certain limit. The second case, called EW effective theory (EWET), EW chiral Lagrangian (EWChL) or Higgs effective theory (HEFT), is a more general (non-linear) realization of the EW symmetry breaking, which includes the SMEFT as a particular case It allows for rather large deviations from the Standard Model in the Higgs sector compared to the well-tested gauge-fermion sector. Appendix C analyzes the special case of a Higgsed heavy scalar resonance with enhanced couplings proportional to its mass, and appendix D discusses the diagonalization of the quadratic fermion Lagrangian through a redefinition of the (light and heavy) fermionic fields
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