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You can take a global symmetry and promote it to a local gauge symmetry by introducing an appropriate gauge field and upgrading the partial derivative to a covariant derivative. The photon field arises from global $U(1)$ symmetry, the gluon field from $SU(3)$ and even gravity shows up this way (though it's more elaborate since the symmetry group of general coordinate transformations is infinite and compact, differently from your usual $SU(N)$).

What gauge field do I get from Lorentz symmetry?

Cosmas Zachos
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Koaaala
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1 Answers1

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It is the celebrated spin connection on the tangent space, gauging Lorentz rotations so you can take Lorentz covariant derivatives on spinors---you would not be able to do Supergravity without it.

As you see, however, $\omega_\mu^{ab}$ is a composite gauge field, that is, it is is an elaborate function of Vierbeine (or Vielbeine) and their derivatives, ensuring tangent space Lorentz invariance, and not a fundamental field. No matter, it is necessary, and GR fermions live by it!

You might enjoy this review.

Cosmas Zachos
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