The discussion revolves around the implications of introducing a momentum cutoff in the context of Lorentz violation and its effects on the vacuum state. Participants explore the theoretical consequences of a preferred frame and how this affects the notion of an 'empty' vacuum, particularly in relation to ground states and observations in different frames.
Participants express differing views on the implications of Lorentz violation and the nature of the vacuum state. There is no consensus on how to approach the calculations or the expected observations resulting from the introduction of a momentum cutoff.
Limitations include the dependence on the definitions of 'empty' vacuum and ground state, as well as the unresolved nature of the calculations regarding boosts and their effects on the vacuum state.
Correct. But if Lorentz symmetry is no longer the symmetry of the theory, then it is pretty much pointlesss to even ask how the vacuum (or anything else) looks in other Lorentz frames.asimov42 said:By 'empty' I mean that the vacuum can only be in the ground state in the preferred frame, correct?
An ugly but consistent theory that can be compared with experiments.asimov42 said:Thanks @Demystifier. If one were to do the totally naive thing and introduce a momentum cutoff in the preferred frame, without changing other aspects of the theory, what would one expect to observe?
Yes. I would call it a computational approximation rather than a "theory". Like ignoring the curvature of the Earth in a ballistic calculation.asimov42 said:make the ground state in the preferred frame look excited in another
I think it depends on how exactly do you compute the boost, i.e. what do you keep fixed. Have you tried to do the actual calculation? For free fields it should not be difficult.asimov42 said:Certainly - but then there should be an expected (predicted) observation. For example, applying a boost in the 'right' direction should make the ground state in the preferred frame look excited in another, no?