Cyclotomic Euler norm factor at a new prime
ID: cyclotomic-euler-norm-factor-at-a-new-prime
Let be outside the excluded primes, let have order , and let be a primitive qth root of unity. Galois equivariance identifies the conjugates with for . The distribution axiom includes the missing factor, so the field norm is . Arithmetic Frobenius sends to , giving the displayed factor. At higher powers of an already ramified prime all q translates occur instead. These are different norm relations; norm compatibility in just a p-power tower does not supply the auxiliary-prime relation by itself.
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