Is it possible to construct a gauge theory with local ISO(3) symmetry?

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Discussion Overview

The discussion revolves around the feasibility of constructing a gauge theory with local ISO(3) symmetry, specifically focusing on the implications for a Lagrangian involving classical fields. Participants explore the theoretical aspects of this symmetry, including its potential pathologies and the formulation of a suitable Lagrangian.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the possibility of building a gauge theory with local ISO(3) symmetry, defining ISO(3) as encompassing three-dimensional rotations and translations.
  • Another participant notes that the non-compact nature of the group due to translations may lead to issues with ghosts.
  • A different participant questions whether the focus on a classical Lagrangian invariant under local ISO(3) is still problematic, despite not intending to quantize the theory.
  • Concerns are raised about the mass term in the Lagrangian, suggesting that the presence of translations complicates the formulation, particularly with the introduction of additional terms that arise from the transformation.
  • One participant proposes a Lagrangian that depends solely on the derivatives of the fields, indicating that the covariant derivative should be determined by the transformation rules under ISO(3) gauge transformations.

Areas of Agreement / Disagreement

Participants express differing views on the implications of including translations in the gauge theory, with some suggesting it leads to pathologies while others explore the possibility of formulating a consistent Lagrangian. The discussion remains unresolved regarding the viability of a gauge theory with local ISO(3) symmetry.

Contextual Notes

Participants highlight potential issues related to the non-compact nature of the ISO(3) group and the complications introduced by mass terms and translations in the Lagrangian. There are unresolved questions regarding the treatment of these terms and their implications for the theory.

Einj
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Hello everyone. Does anyone know if it is possible to build a gauge theory with a local ISO(3) symmetry (say a Yang-Mills theory)? By ISO(3) I mean the group composed by three-dimensional rotations and translations, i.e. if ##\phi^I## are three scalars, I'm looking for a symmetry under:
$$
\phi^I\to O^{IJ}\phi^J,
$$
with ##O^{IJ}\in SO(3)## and under:
$$
\phi^I\to\phi^I+a^I.
$$

Thanks!
 
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This group is not compact due to the translations. Usually this leads to problems with ghosts.
 
I don't want to quantize the theory. I'm just looking for a Lagrangian for classical fields invariant under local ISO(3). Is this still pathological?
 
I think the translation makes it pathological... Take for example the mass term:
[itex]m^2 \phi^2 \rightarrow m^2 (\phi^2 + 2 a \phi + a^2)[/itex]
Maybe you can drop the third term off your Lagrangian, but the second term doesn't seem right... and I don't think there is a way to get rid of it.
If the field is massless, then the kinetic terms work fine with the translations and a term like
[itex]|\partial \phi|^2[/itex] seems fine, as long as [itex]a^I \ne a^I(x)[/itex].
If it's local, then it's pretty similar to a local U(1).
 
Last edited:
Yes, I'm talking about a Lagrangian that only depends on derivative of the fields in the form ##\mathcal{L}(|D_\mu\phi|^2)##, where the covariant derivative must be found by imposing the right transformation rules under an ISO(3) gauge transformation. In particular, I'm writing an infinitesimal transformation as ##U=1+i\alpha^ap^a+i\beta^aJ^a##, with ##p^a## and ##J^a## being the generators of the shifts and rotations. Do you think this is possible?
 

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