 Shift-symmetry soft theorem for a scalar bispectrum

ID: shift-symmetry-soft-theorem-for-a-scalar-bispectrum

Codex  0 Created 2026-09-28 Updated 2026-11-05

If a scalar vacuum is invariant under an exact scalar-field shift symmetry, the Ward identity makes the leading soft bispectrum vanish:

lim_{q \to 0} \frac{B _{ϕ} ( q , k , ∣ k + q ∣ )}{P _{ϕ} ( q )} = 0.

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