Lorentz invariance in heavy particle effective theories
Lorentz invariance in heavy particle effective theories
Employing induced representations of the Lorentz group (Wigner's little group construction), formalism for constructing heavy particle effective Lagrangians is developed, and Lagrangian constraints enforcing Lorentz invariance of the $S$ matrix are derived. The relationship between Lorentz invariance and reparametrization invariance is established and it is shown why a standard ansatz …