Lorentz Violation from the Higgs Portal

Understand

We study bounds and signatures of models where the Higgs doublet has an inhomo- geneous mass or vacuum expectation value, being coupled to a hidden sector that breaks Lorentz invariance.

• This physics is best described by a low-energy effective Lagrangian in which the Higgs speed-of-light is smaller than c; such effect is naturally small because it is suppressed by four powers of the inhomogeneity scale.
• The Lorentz violation in the Higgs sector is communicated at tree level to fermions (via Yukawa interactions) and to massive gauge bosons, although the most important effect comes from one-loop dia- grams for photons and from two-loop diagrams for fermions.
• We calculate these effects by deriving the renormalization-group equations for the speed-of-light of the Standard Model particles.