Uncertainties in Constraints from Pair Production on Superluminal Neutrinos

The use of the vacuum lepton pair production process ($\nu \to \nu e^- e^+$), a viable reaction for superluminal neutrinos, to put constraints on Lorentz violations requires a dynamical framework. Different choices of dynamical matrix elements and modified dispersion relations for neutrinos, leading to numerical factors differing by one order of magnitude in the results for the pair production decay width, are used to show the uncertainties on these constraints.