Abstract

Recent claims point out that possible violations of Lorentz symmetry appearing in some semiclassical models of extended matter dynamics motivated by loop quantum gravity can be removed by a different choice of phase-space variables. In this note we show that such alternative is inconsistent with (i) the choice of variables in the regularized underlying quantum theory from which the effective theories are derived and (ii) the application of the correspondence principle. A consistent choice will violate standard Lorentz invariance, with the exception of trivial zero Planck scale corrections which are allowed by the analysis. Thus, for nontrivial corrections, to preserve a relativity principle in these models, the linear realization of Lorentz symmetry should be extended or superseded.