Abstract
With the renewed interest in vector-like fermion extensions of the Standard Model, we present here a study of multiple vector-like theories and their phenomenological implications. Our focus is mostly on minimal flavor conserving theories that couple the vector-like fermions to the SM gauge fields and mix only weakly with SM fermions so as to avoid flavor problems. We present calculations for precision electroweak and vector-like state decays, which are needed to investigate compatibility with currently known data. We investigate the impact of vector-like fermions on Higgs boson production and decay, including loop contributions, in a wide variety of vector-like extensions and their parameter spaces.
Highlights
The Standard Model (SM) of particle physics is a chiral theory under the electroweak gauge symmetries, SU(2)L×U(1)Y
With the renewed interest in vector-like fermion extensions of the Standard Model, we present here a study of multiple vector-like theories and their phenomenological implications
We investigate the impact of vector-like fermions on Higgs boson production and decay, including loop contributions, in a wide variety of vector-like extensions and their parameter spaces
Summary
The Standard Model (SM) of particle physics is a chiral theory under the electroweak gauge symmetries, SU(2)L×U(1)Y. [35, 36] considers a vector-like lepton generation (including new SU(2) singlets) and the possibility of the electromagnetic charge neutral vector-like lepton being a dark matter candidate They analyze precision electroweak bounds, modifications to Higgs observables and vacuum stability bounds for this extension. The constraints from shifts to Zbb couplings on their model is very tight, while this will not apply in our case since we do not allow any significant Yukawa coupling between the new SU(2) vector-like doublet and SM singlets; (b) they only consider quarks while we include leptons ; (c) we include the recent LHC Higgs data while their study was done before the Higgs discovery. We conclude with a brief discussion on the meaning of the results in the context of some theories of physics beyond the SM, and discuss what the future may hold in our search for vector-like states
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