- #1

MathematicalPhysicist

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Now, as far as I can tell the generators of ##U(1)## are just exponents, i.e ##e^{2\pi ix}##, so how can they have a zero trace if it's just one number which never vanishes?...if the gauge group of the theory contains ##U(1)## factors, the theory cannot be consistently coupled to gravity unless each of the ##U(1)## generators is traceless.

Perhaps I am missing something here, can anyone clear this matter to me?

Ah, wait perhaps this contradiction means that you cannot couple gravity to this theory?