Is there an algebraic field extension K/Q such that AutQ(K)≅Z?
Here I mean the field automorphisms (which are necessarily Q-algebras automorphisms) of course.
According to this answer, one can find some extension of Q whose automorphism group is Z. But I've not seen that one can expect this extension to be algebraic.
At least such an extension can't be normal, otherwise Z would be endowed with a topology turning it into a profinite group, which can't be countably infinite.
(So typically, if we replace Q by Fp, then the answer to the above question is no, because any algebraic extension of a finite field is Galois).
Thank you!
Answer
Let L be the fixed field of AutQ(K), so Q⊊, and K/L is a normal extension with Galois group \Bbb Z, which is impossible.
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