Removing extraneous factors in Einstein Action

  • #1
311
1
I have an action of the form
[tex]
\int \alpha \sqrt{g} R
[/tex]
where [itex]\alpha[/itex] is a field.
I want to do some kind of coordinate transformation, so that this term in the action becomes
[tex]
\int \sqrt{g}R + \sqrt{g}(...)
[/tex]
where (...) consists of terms containing \alpha.

So basically, I want to remove [itex]\alpha[/itex] from the coefficient of R and move it to other terms in the lagrangian. Now, I know that this can be done! (I remember this from long ago), but for heaven's sake can't figure out how!

Can any one tell me? Just a reference would be fine.
 

Answers and Replies

  • #2
95
1
You probably want a field redefinition, not a coordinate transformation. I'd look up "Jordan frame" and "Einstein Frame" in "Brans Dicke Theory" (which contains an action like the one you write).
 
  • #3
311
1
You probably want a field redefinition, not a coordinate transformation. I'd look up "Jordan frame" and "Einstein Frame" in "Brans Dicke Theory" (which contains an action like the one you write).
Yes. That's exactly what I wanted. Thanks a lot Sam. However, it turns out that this process cannot be done in 2 dimensions which is what I am working in.

Anyway thanks a lot for your help.
 

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