Hadronic Lorentz Violation in Chiral Perturbation Theory Including the Coupling to External Fields

Understand

If any violation of Lorentz symmetry exists in the hadron sector, its ultimate origins must lie at the quark level.

• We continue the analysis of how the theories at these two levels are connected, using chiral perturbation theory.
• Considering a two-flavor quark theory, with dimension-4 operators that break Lorentz symmetry, we derive a low-energy theory of pions and nucleons that is invariant under local chiral transformations and includes the coupling to external fields.
• The pure meson and baryon sectors, as well as the couplings between them and the couplings to external electromagnetic and weak gauge fields, contain forms of Lorentz violation which depend on linear combinations of quark-level coefficients.