Complex sentence: While hypothetical tachyons are thought to be compatible with Lorentz invariance, superluminal neutrinos have also been studied in Lorentz invariance violating frameworkds as motivated by speculative variants of quantum gravity, such as the Standard-Model Extension according to which Lorentz-violating neutrino oscillations can arise.
Split into simpler sentences: While hypothetical tachyons are thought to be compatible with Lorentz invariance, superluminal neutrinos have also been studied in Lorentz invariance violating models as motivated by speculative variants of quantum gravity. A framework to study such violations is the Standard-Model Extension according to which Lorentz-violating neutrino oscillations can arise.