Make sure the Lagrangian symmetry?

  • Context: Graduate 
  • Thread starter Thread starter centry57
  • Start date Start date
  • Tags Tags
    Lagrangian Symmetry
Click For Summary

Discussion Overview

The discussion revolves around the symmetry properties of the Lagrangian for the neutral Proca field, specifically questioning whether it is symmetric and how to verify this symmetry. The focus includes theoretical implications and mathematical reasoning related to the stress-energy tensor.

Discussion Character

  • Technical explanation, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant questions the symmetry of the Lagrangian \(\mathcal{L}=-\frac{1}{16\pi}\left(F^{\mu\nu}F_{\mu\nu}-2m^2 A_{\mu} A^{\mu}\right)\) and seeks clarification on how to determine its symmetry.
  • Another participant asks for clarification on what aspect of symmetry is being referred to.
  • A participant specifies that they are interested in whether the stress-energy momentum tensor \(T_{\mu\nu}\) is symmetric, indicating a focus on the implications of this property.
  • Another reply suggests taking the functional derivative of the Lagrangian with respect to the metric to explore the symmetry, and mentions the possibility of constructing the Belinfante tensor if the electromagnetic tensor is not symmetric.

Areas of Agreement / Disagreement

The discussion contains multiple viewpoints regarding the symmetry of the Lagrangian and its implications, with no consensus reached on the matter.

Contextual Notes

Participants have not fully defined the specific type of symmetry being discussed, and there are unresolved assumptions regarding the properties of the stress-energy tensor and the electromagnetic tensor.

centry57
Messages
8
Reaction score
0
Is the Lagrangian of the neutral Proca field
[tex]\mathcal{L}=-\frac{1}{16\pi}\left(F^{\mu\nu}F_{\mu\nu}-2m^2 A_{\mu} A^{\mu}\right)[/tex]
symmetric?
And How to make sure whether it's symmetric.
 
Physics news on Phys.org
centry57 said:
Is the Lagrangian of the neutral Proca field
[tex]\mathcal{L}=-\frac{1}{16\pi}\left(F^{\mu\nu}F_{\mu\nu}-2m^2 A_{\mu} A^{\mu}\right)[/tex]
symmetric?
And How to make sure whether it's symmetric.

Symmetric in what?

AB
 
I mean if the Stress-energy momentum has the form [tex]T_{\mu\nu}=T_{\nu\mu}[/tex]
 
Well, take the functional derivative with respect to the metric of this Lagrangian. What do you get?

If the EM-tensor is not symmetric, you can construct the so-called Belinfante tensor; see for instance DiFrancesco's "Conformal Field Theory", 2.5.1 :)
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 9 ·
Replies
9
Views
1K
  • · Replies 44 ·
2
Replies
44
Views
4K
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
963
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K