Emergent Lorentz Signature, Fermions, and the Standard Model
  This article investigates the construction of fermions and the formulation of
the Standard Model of particle physics in a theory in which the Lorentz
signature emerges from an underlying microscopic purely Euclidean $SO(4)$
theory. Couplings to a clock field are responsible for triggering the change of
signature of the effective metric in which the standard fields propagate. We
demonstrate that Weyl and Majorana fermions can be constructed in this
framework. This construction differs from other studies of Euclidean fermions,
as the coupling to the clock field allows us to write down an action which
flows to the usual action in Minkowski spacetime. We then show how the Standard
Model can be obtained in this theory and consider the constraints on
non-Standard-Model operators which can appear in the QED sector due to CPT and
Lorentz violation.
