Momentum cutoff, Lorentz violation and the vacuum state

  • #1
asimov42
377
3
Hi all - related to a question I asked some time ago: If one introduces a momentum cutoff, the result in the most basic case is Lorentz violation. That is, some form of preferred frame must be introduced. I'm wondering what this does to the vacuum state? That is, how does one keep the vacuum 'empty' despite this preferred frame? Or does the notion of the vacuum have to change?
 

Answers and Replies

  • #2
asimov42
377
3
By 'empty' I mean that the vacuum can only be in the ground state in the preferred frame, correct?
 
  • #3
Demystifier
Science Advisor
Insights Author
Gold Member
13,281
5,680
By 'empty' I mean that the vacuum can only be in the ground state in the preferred frame, correct?
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.
 
  • #4
asimov42
377
3
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?
 
  • #5
Demystifier
Science Advisor
Insights Author
Gold Member
13,281
5,680
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?
An ugly but consistent theory that can be compared with experiments.
 
  • #6
asimov42
377
3
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?
 
  • #7
Keith_McClary
722
1,439
make the ground state in the preferred frame look excited in another
Yes. I would call it a computational approximation rather than a "theory". Like ignoring the curvature of the Earth in a ballistic calculation.
 
  • #8
Demystifier
Science Advisor
Insights Author
Gold Member
13,281
5,680
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?
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.
 

Suggested for: Momentum cutoff, Lorentz violation and the vacuum state

Replies
8
Views
686
Replies
3
Views
715
Replies
20
Views
1K
Replies
4
Views
1K
Replies
9
Views
774
Replies
4
Views
626
Replies
1
Views
926
Replies
40
Views
689
Replies
24
Views
1K
  • Last Post
Replies
5
Views
1K
Top