A zero would leave a fingerprint
Reduce the theorem to showing a sum of Möbius signs has a power saving.
Turn 4 showed that a zero ρ = β + iγ of zeta makes a wave of size xβ in the primes. The same is true for the Möbius sum: 1/ζ has a blow-up wherever ζ has a zero, and that blow-up shows up as a wave of size Dβ in the sum of μ(n) over n near D. So if we can prove the Möbius sum is always smaller than D11/12+ε, no zero can have β > 11/12. The wave would eventually burst through the ceiling.
Fix a Hecke character ν and a smooth bump W. The smoothed, twisted Möbius sum is
about D terms of size at most 1. Trivially |A₁(D)| ≤ D. The goal is a power saving A₁(D) ≪ D11/12+ε. Then the integral ∫ A₁(D) D−s dD/D converges for Re s > 11/12 and equals Ŵ(s)/L(s, ν). If L(ρ, ν) = 0 for some Re ρ > 11/12, choose W so that Ŵ(ρ) > 0. The left side is finite, the right side is infinite, contradiction.
“We will deduce Theorem 1.1 from a power-saving estimate for ν-twisted Möbius sums … A₁(D) ≪ D1−δ+ε for every W.” The deduction in Section 3 picks W(y) = y−ρφ(y) with φ ≥ 0, so that Ŵ(ρ) = ∫φ(y) dy/y > 0, and evaluates LS(s,ν)·𝓜W(s) = Ŵ(s) at s = ρ to get 0 = Ŵ(ρ) > 0.Section 2.1 and the proof of Theorem 1.1 in Section 3
The Dirichlet case follows from quadratic base change, LK(s, χ∘N) = L(s, χ) L(s, χχ−3), plus L(1, χ−3) > 0 to rule out a cancellation at s = 1.
Both axes are logarithmic, so powers of D become straight lines. Typical Möbius noise is around D1/2. A zero at β adds an oscillating wave of size Dβ. Any β above 11/12 makes a steeper line, which must eventually cross the ceiling.