The smearing operator ∫ a(t) U(t) dt #
The smearing operator ξ ↦ ∫ a(t) U(t) ξ dt of a uniformly bounded strongly continuous
family U against an integrable weight a.
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Smearing a family of elements of a von Neumann algebra stays in it.
Exchange: ∫ a(t) Δ^{it} ζ dt = â(θ)(R) ζ #
∫ a(t) Δ^{it} dt = Ĝ(R) where Ĝ(l) = ∫ a(t) e^{itθ(l)} dt.
Gaussians and their Fourier transforms #
The modulated Gaussian a_k^♭(t) = e^{k/4} a_k(t) e^{-ikt}.
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- CommutingRepetition.VN.Modular.gaussFlat k t = ↑(Real.exp (k / 4)) * ↑(CommutingRepetition.VN.Modular.gauss k t) * Complex.exp (-(↑(k * t) * Complex.I))
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The spectral functions e^{-θ²/(4k)} and e^{-θ²/(4k)} e^{θ/2} #
gk k l = e^{-θ(l)²/(4k)}.
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- CommutingRepetition.VN.Modular.gk k l = Real.exp (-CommutingRepetition.VN.Modular.θ l ^ 2 / (4 * k))
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The smeared elements x_k and x_k^♭ #
The Gaussian smearing x_k = ∫ a_k(t) σ_t(x) dt.
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- One or more equations did not get rendered due to their size.
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The companion x_k^♭ = e^{k/4} ∫ a_k(t) e^{-ikt} σ_t(x*) dt.
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- One or more equations did not get rendered due to their size.
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x_k Ω = e^{-θ²/(4k)}(R) xΩ.
x_k^♭ Ω = (e^{-θ²/(4k)} e^{θ/2})(R) x*Ω.
The key identity J x_k^♭ Ω = x_k Ω.
Left boundedness #
For c ∈ M′ and 0 ≤ y ∈ M: ⟪cΩ, y cΩ⟫ ≤ ‖c‖² ⟪Ω, yΩ⟫.
HJX Lemma 2.5(i) for the smeared elements: ψ(x_k* y x_k) ≤ ‖x_k^♭‖² ψ(y) for
0 ≤ y ∈ M.
Convergence x_k Ω → xΩ #
x_k Ω → xΩ along k = n + 1 → ∞: the smeared elements are ‖·‖_ψ-dense.