What kinds of inconsistencies would one get if one starts with Lorentz noninvariant Lagrangian of QFT? The question is motivated by this preprint arXiv:1203.0609 by Murayama and Watanabe.
Also, what is the basic difference between
a theory that is non-relativistic approximation to relativistic theory, and
a fundamentally Lorentz non-invariant theory?